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480–1

Copyright © 1998 NFPA, All Rights Reserved

NFPA 480

Standard for the

Storage, Handling, and Processing of Magnesium Solids and Powders

1998 Edition

This edition of NFPA 480, Standard for the Storage, Handling, and Processing of Magnesium Sol-ids and Powders, was prepared by the Technical Committee on Combustible Metals and MetalDusts and acted on by the National Fire Protection Association, Inc., at its Annual Meetingheld May 18–21, 1998, in Cincinnati, OH. It was issued by the Standards Council on July 16,1998, with an effective date of August 5, 1998, and supersedes all previous edition.

Changes other than editorial are indicated by a vertical rule in the margin of the pages onwhich they appear. These lines are included as an aid to the user in identifying changes fromthe previous edition.

This edition of NFPA 480 was approved as an American National Standard on August 6,1998.

Origin and Development of NFPA 480This standard was begun in 1946, tentatively adopted in 1950, and adopted by the National

Fire Protection Association in May 1951. Revisions were adopted by the Association in 1952,1954, 1957, 1959, 1961, and 1967. The 1967 edition was reconfirmed in 1974.

The 1974 edition was completely revised in 1980, primarily to comply with the NFPA Man-ual of Style. Minor technical amendments were made at that time. This complete revision ofthe 1974 edition was acted on by the Association at its 1981 Fall Meeting, and the revision wasdesignated the 1982 edition.

The 1987 edition was a reconfirmation of the 1982 edition. The only changes made wereminor editorial improvements and redesignation of the standard as NFPA 480.

For the 1993 edition, the Committee completely revised the standard to update therequirements for safe handling of magnesium solids and powders as well to update the fireand dust explosion prevention measures for both. The Committee incorporated the require-ments for safe handling of magnesium powder that were previously found in the 1987 editionof NFPA 651, Standard for the Manufacture of Aluminum and Magnesium Powder (retitled Standardfor the Machining and Finishing of Aluminum and the Production and Handling of Aluminum Pow-ders in 1998). The Committee revision also incorporated editorial and style revisions to com-ply with the NFPA Manual of Style and to assist in making the document more usable,adoptable, and enforceable.

The 1998 revision incorporates amendments to the entire document. Key changes havebeen made to Section 4-2 to consolidate requirements applicable to all dust collectors; toparagraph 7-1.2 to add requirements for vacuum cleaning systems; and to Chapter 9 to incor-porate fire prevention concepts and fire protection methods developed for other combusti-ble metals.

480–2 STORAGE, HANDLING, AND PROCESSING OF MAGNESIUM SOLIDS AND POWDERS

1998

Technical Committee on Combustible Metals and Metal Dusts

Waldemar Seton, Chair SJO Consulting Engr, OR [SE]

Roy E. Adams, TIMET, NV [M]Rep. Int’l Titanium Assn.

Tom Christman, Lockheed Martin Energy Systems, TN [U]R. Thomas Currin, Postin Products, Inc., NC [U]Joseph A. Domanico, U.S. Dept. of the Army, MD [RT]John A. Gatchell, Wah Chang, Albany, OR [M]

Ralph W. Hawk, Cyprus Foote Mineral Co., NC [U]Kevin M. Laporte, Uni-Wash/Polaris, MI [M]John E. McConaghie, Reade Mfg. Co., NJ [U]David L. Oberholtzer, Valimet, Inc., CA [M]

Rep. The Aluminum Assn.John Valiulis, Factory Mutual Research Corp. MA [I]

Alternates

W. Anthony Major, Silberline Mfg. Co., Inc., PA [M](Alt. to D. L. Oberholtzer)

Larry J. Moore, Factory Mutual Research Corp., CO [I](Alt. to J. Valiulis)

Nonvoting

Thomas J. Matesic, Reactive Metals & Alloys Corp., PA Albert Muller, Lebanon, NJ(Member Emeritus)

Martha H. Curtis, NFPA Staff Liaison

This list represents the membership at the time the Committee was balloted on the text of this edition. Since that time,changes in the membership may have occurred. A key to classifications is found at the back of this document.

NOTE: Membership on a committee shall not in and of itself constitute an endorsement of the Associationor any document developed by the committee on which the member serves.

Committee Scope: This Committee shall have primary responsibility for documents on safeguards againstfire and explosion in the manufacturing, processing, handling, and storage of combustible metals, powders,and dusts.

Edition

CONTENTS 480–3

1998 Edition

Contents

Chapter 1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . 480– 4

1-1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480– 4

1-2 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480– 4

1-3 Equivalent Protection . . . . . . . . . . . . . . . . . . . . 480– 4

1-4 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480– 4

Chapter 2 Location and Construction of Magnesium Powder Production Plants . . . . . . . . . . . 480– 4

2-1 Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480– 4

2-2 Security. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480– 5

2-3 Building Construction. . . . . . . . . . . . . . . . . . . . 480– 5

2-4 Doors and Windows . . . . . . . . . . . . . . . . . . . . . 480– 5

2-5 Grounding of Equipment . . . . . . . . . . . . . . . . . 480– 5

2-6 Electrical Power . . . . . . . . . . . . . . . . . . . . . . . . . 480– 5

Chapter 3 Magnesium Mill and Foundry Operations . . . . . . . . . . . . . . . . . . . . . . . . 480– 5

3-1 Melting and Casting Operations . . . . . . . . . . . 480– 5

3-2 Heat Treating . . . . . . . . . . . . . . . . . . . . . . . . . . 480– 6

Chapter 4 Machining, Finishing, and Fabrication of Magnesium . . . . . . . . . . . . . . . . . . . . . . . . 480– 6

4-1 Machining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480– 6

4-2 Dust Collection . . . . . . . . . . . . . . . . . . . . . . . . . 480– 6

4-3 Cleaning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480– 7

4-4 Electrical Equipment . . . . . . . . . . . . . . . . . . . . 480– 7

4-5 Grounding of Equipment . . . . . . . . . . . . . . . . . 480– 7

4-6 Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . 480– 7

4-7 Drawing, Spinning, and Stamping . . . . . . . . . . 480– 7

Chapter 5 Magnesium Powder—Machinery and Operations . . . . . . . . . . . . . . . . . . . . . . . . 480– 8

5-1 General Precautions . . . . . . . . . . . . . . . . . . . . . 480– 8

5-2 Requirements for Machinery . . . . . . . . . . . . . . 480– 8

5-3 Start-Up Operations . . . . . . . . . . . . . . . . . . . . . 480– 8

5-4 Charging and Discharging . . . . . . . . . . . . . . . . 480– 8

5-5 Packaging and Storage . . . . . . . . . . . . . . . . . . . 480– 8

Chapter 6 In-Plant Conveying of Magnesium Powder. . . . . . . . . . . . . . . . . . . . . . . . . . . . 480– 8

6-1 Containers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480– 86-2 Pneumatic Conveying . . . . . . . . . . . . . . . . . . . 480– 86-3 Ductwork for Conveying Systems . . . . . . . . . . 480– 86-4 Fan Construction and Arrangement . . . . . . . . 480– 96-5 Dust Collectors . . . . . . . . . . . . . . . . . . . . . . . . . 480– 9

Chapter 7 Prevention of Fugitive Dust Accumulations . . . . . . . . . . . . . . . . . . . . . . 480– 9

7-1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480– 97-2 Cleaning Frequency . . . . . . . . . . . . . . . . . . . . . 480– 9

Chapter 8 Storage of Magnesium Solids . . . . . . . . . 480– 98-1 Storage of Pigs, Ingots, and Billets . . . . . . . . . 480– 98-2 Storage of Heavy Castings . . . . . . . . . . . . . . . . 480–108-3 Storage of Light Castings . . . . . . . . . . . . . . . . . 480–108-4 Storage in Racks or Bins . . . . . . . . . . . . . . . . . 480–108-5 Storage of Scrap Magnesium . . . . . . . . . . . . . . 480–108-6 Storage of Magnesium Powder . . . . . . . . . . . . 480–118-7 Storage of Other Magnesium Products. . . . . . 480–11

Chapter 9 Fire Prevention and Fire Protection . . . . 480–119-1 Fire Prevention . . . . . . . . . . . . . . . . . . . . . . . . . 480–119-2 General Fire Protection . . . . . . . . . . . . . . . . . . 480–129-3 Extinguishing Agents and Application

Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480–12

Chapter 10 Referenced Publications . . . . . . . . . . . . 480–12

Appendix A Explanatory Material . . . . . . . . . . . . . . . 480–13

Appendix B Supplementary Information on Magnesium 480–16

Appendix C Explosibility of Magnesium Dust 480–18

Appendix D Referenced Publications 480–22

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480–22

480–4 STORAGE, HANDLING, AND PROCESSING OF MAGNESIUM SOLIDS AND POWDERS

NFPA 480

Standard for the

Storage, Handling, and Processing ofMagnesium Solids and Powders

1998 Edition

NOTICE: An asterisk (*) following the number or letter des-ignating a paragraph indicates that explanatory material onthe paragraph can be found in Appendix A.

Information on referenced publications can be found inChapter 10 and Appendix D.

Chapter 1 General

1-1 Scope.

1-1.1 This standard shall apply to the storage, handling, andprocessing of magnesium solids at magnesium foundries, pro-cessing plants, and commercial storage facilities.

1-1.2 This standard shall also apply to the storage, handling,processing, and manufacture of magnesium powder.

1-1.3 This standard shall not apply to the primary productionof magnesium.

1-1.4* This standard shall not apply to the transportation ofmagnesium in any form on public highways, waterways, or byair or rail.

1-1.5 The requirements of NFPA 650, Standard for PneumaticConveying Systems for Handling Combustible Particulate Solids,shall not apply to magnesium.

1-2 Purpose. The purpose of this standard is to minimize theoccurrence of and resulting damage from fire and explosionhazards in the storage, handling, processing, and manufac-ture of magnesium solids and powders.

1-3 Equivalent Protection.

1-3.1 Existing plants, equipment, structures, and installationsthat do not comply strictly with the requirements of this stan-dard shall be considered to be in compliance if it can be shownthat an equivalent level of protection has been provided, orthat no specific hazard shall be created or continue to existthrough noncompliance.

1-3.2 This standard shall not be intended to prevent the useof systems, methods, or devices that provide equivalent protec-tion from fire and explosion. NFPA 69, Standard on ExplosionPrevention Systems, shall be referenced where considering theuse of optional systems.

1-4 Definitions. For the purpose of this standard, the termsbelow shall be defined as follows.

Approved.* Acceptable to the authority having jurisdic-tion.

Authority Having Jurisdiction.* The organization, office, orindividual responsible for approving equipment, an installa-tion, or a procedure.

Fire-Resistive. Meeting the requirements for Type I orType II construction, as described in NFPA 220, Standard onTypes of Building Construction.

Heavy Casting. Castings greater than 25 lb (11.3 kg) withwalls of large cross-sectional weights [at least 1/4 in. (6.4 mm)].Castings less than 25 lb (11.3 kg) are considered light castings.

Labeled. Equipment or materials to which has beenattached a label, symbol, or other identifying mark of an orga-nization that is acceptable to the authority having jurisdictionand concerned with product evaluation, that maintains peri-odic inspection of production of labeled equipment or materi-als, and by whose labeling the manufacturer indicatescompliance with appropriate standards or performance in aspecified manner.

Listed.* Equipment, materials, or services included in a listpublished by an organization that is acceptable to the author-ity having jurisdiction and concerned with evaluation of prod-ucts or services, that maintains periodic inspection ofproduction of listed equipment or materials or periodic eval-uation of services, and whose listing states that either theequipment, material, or service meets identified standards orhas been tested and found suitable for a specified purpose.

Magnesium. Refers to either pure metal or alloys havingthe generally recognized properties of magnesium marketedunder different trade names and designations.

Magnesium Powder. Refers to magnesium metal in theform of a chip, granule, flake, or finely divided particle. Anysuch magnesium metal that is less than 1/8 in. (3.2 mm) in twodimensions or less than 1/20 in. (1.3 mm) in single dimension(e.g., magnesium ribbon) will be considered a powder.

Magnesium Powder Production Plant. Facilities or build-ings whose primary product is bulk magnesium powder. Facil-ities or buildings in which powder is produced incidental tooperations will not be considered a powder production plant.

Noncombustible. In the form used and under the condi-tions anticipated, will not ignite, burn, support combustion, orrelease flammable vapors when subjected to fire or heat.(Materials reported as noncombustible, when tested in accor-dance with ASTM E 136, Standard Test Method for Behavior ofMaterials in a Vertical Tube Furnace at 750°C, shall be considerednoncombustible materials.)

Shall. Indicates a mandatory requirement.

Should. Indicates a recommendation or that which isadvised but not required.

Standard. A document, the main text of which containsonly mandatory provisions using the word “shall” to indicaterequirements and which is in a form generally suitable formandatory reference by another standard or code or for adop-tion into law. Nonmandatory provisions shall be located in anappendix, footnote, or fine-print note and are not to be con-sidered a part of the requirements of a standard.

Swarf. Finely divided metal particles produced by sawingand cutting operations.

Chapter 2 Location and Construction of Magnesium Powder Production Plants

2-1 Location.

2-1.1 Magnesium powder production plants shall be locatedon a site large enough so that the buildings in which powderis manufactured shall be at least 300 ft (91.5 m) from publicroads and from any occupied structure, such as public build-ings, dwellings, and business or manufacturing establish-

1998 Edition

MAGNESIUM MILL AND FOUNDRY OPERATIONS 480–5

ments, other than those buildings that are a part of themagnesium powder production plant.

2-1.2 Different production operations shall be located in sep-arate but not adjoining buildings that are located at least 50 ft(15 m) from each other.

Exception: Two buildings less than 50 ft (15 m) apart shall be permit-ted if the facing wall of the exposed building shall be capable of resist-ing a blast pressure of 2.0 psig (13.8 kPa gauge) and shall be nonload-bearing, noncombustible, and without openings.

2-1.3 Separate buildings shall be required where differentoperations, such as but not limited to atomization, grinding,crushing, screening, blending, or packaging are performed.

Exception: More than one operation within the same building shall bepermitted if the design provides equivalent protection.

2-2 Security.

2-2.1 This section shall be applied to new and existing facili-ties. The intent of this section shall be to restrict access by thegeneral public to those facilities and to establish adequate exitfacilities for personnel.

2-2.2 The powder production plant shall be surrounded bystrong fencing at least 6 ft (1.8 m) high with suitable entrancegates, or otherwise shall be rendered inaccessible.

2-2.3 Security measures taken shall be in accordance withNFPA 101®, Life Safety Code®.

2-3 Building Construction.

2-3.1 All buildings used for the manufacture, packing, orloading for shipment of magnesium powders shall be singlestory, without basements, constructed of noncombustiblematerials throughout, and shall have nonload-bearing walls.The buildings shall be designed so that all internal surfacesare readily accessible to facilitate cleaning.

Exception: Other construction types shall be permitted if equivalentprotection can be demonstrated.

2-3.2 All walls or areas that are not of monolithic constructionand where dust can be produced, shall have all masonry jointsthoroughly slushed with mortar and troweled smooth so as toleave no interior or exterior voids where magnesium powdercan infiltrate and accumulate.

2-3.3 Floors shall be noncombustible hard surface and non-slip, installed with a minimum number of joints in which pow-der can collect. The requirements of this subsection shall alsoapply to elevated platforms, balconies, floors, or gratings. (SeeAppendix B.)

2-3.4 Roofs of buildings that house dust-producing opera-tions shall be supported on girders or structural membersdesigned to minimize surfaces on which dust can collect.

2-3.5 Roof decks shall be watertight.

2-4 Doors and Windows.

2-4.1 All exits shall conform with NFPA 101, Life Safety Code.

2-4.2 All doors in fire-rated partitions shall be approved, self-closing fire doors, installed in accordance with NFPA 80, Stan-dard for Fire Doors and Fire Windows.

2-4.3* Windows shall be held in place by friction latches andinstalled so that they open outward.

2-5* Grounding of Equipment. All process equipment andall building steel shall be securely grounded by permanentground wires to prevent accumulation of static electricity.

2-6 Electrical Power.

2-6.1 All electrical equipment and wiring shall be installed inaccordance with NFPA 70, National Electrical Code®.

2-6.2* All parts of manufacturing buildings shall be classified.

2-6.3 Buildings shall be provided with emergency lighting sys-tems in accordance with NFPA 101, Life Safety Code. The emer-gency lighting shall be energized automatically upon loss ofelectrical power to the buildings.

Exception: Buildings of less than 200 ft2(19 m2) not normally occu-pied shall not be required to have emergency lighting systems.

Chapter 3 Magnesium Mill and Foundry Operations

3-1* Melting and Casting Operations.

3-1.1 Buildings used for the melting and casting of magne-sium shall be noncombustible. Melt rooms shall provide accessto facilitate fire control. Floors shall be of noncombustibleconstruction and be kept clean and free of moisture andstanding water.

3-1.2* All solid metal shall be thoroughly dried by preheatingand shall be at a temperature not less than 250°F (121°C)throughout when coming into contact with molten magne-sium.

3-1.3 Fuel supply lines to melting pots and preheating instal-lations shall have remote fuel shutoffs and combustion safetycontrols in accordance with NFPA 86, Standard for Ovens andFurnaces, or equivalent.

3-1.4* Prevention of Molten Magnesium Contact with Foreign Materials.

3-1.4.1 Areas of furnaces that can come into contact with mol-ten magnesium in the event of a runout shall be kept dry andfree of iron oxide.

3-1.4.2 Crucible interiors and covers shall be maintained freeof iron oxide scale, which could fall into the molten metal.

3-1.4.3 Molten magnesium systems shall overflow or relieve tosecondary containments designed to handle 110 percent ofthe largest expected failure and shall be provided with themeans to prevent contact with incompatible materials.

3-1.4.4 Melting pots and crucibles shall be inspected regu-larly. Pots and crucibles that show evidence of possible failureor that allow molten metal to contact iron oxide, concrete, orother incompatible materials shall be repaired or discarded.

3-1.5 Ladles, skimmers, and sludge pans shall be thoroughlydried and preheated before contacting molten metal.

3-1.6 Extreme care shall be exercised in pouring magnesiumcastings to avoid spillage. All molds shall be thoroughly pre-heated before pouring.

3-1.7 Operators in melting and casting areas shall wear flame-resistant clothing, high foundry shoes, and face protection.Clothing worn where molten magnesium is present shall haveno exposed pockets or cuffs that could trap and retain magne-sium.

1998 Edition

480–6 STORAGE, HANDLING, AND PROCESSING OF MAGNESIUM SOLIDS AND POWDERS

3-2* Heat Treating.

3-2.1 A standard procedure for checking the uniformity oftemperatures at various points within heat-treating furnacesshall be established. Furnaces shall be checked prior to useand at regular intervals during use to identify undesirable hotspots.

3-2.2* Gas- or oil-fired furnaces shall be provided with com-bustion safety controls.

3-2.3 All furnaces shall have two sets of temperature controlsoperating independently. One shall maintain the desiredoperating temperature; the other, operating as a high-temper-ature limit control, shall cut off fuel or power to the heat-treat-ing furnace at a temperature slightly above the desiredoperating temperature.

3-2.4 Magnesium parts to be put in a heat-treating furnaceshall be free of magnesium turnings, chips, and swarf.

3-2.5 Combustible spacers on pallets shall not be used in aheat-treating furnace.

3-2.6* Aluminum parts, sheets, or separators shall not beincluded in a furnace load of magnesium.

3-2.7 There shall be strict adherence to the heat-treating tem-perature cycle recommended by the alloy manufacturer.

3-2.8* Molten salt baths containing nitrates or nitrites shallnot be used for heat-treating magnesium alloys.

3-2.9* Magnesium and aluminum metals shall be segregatedand easily identified to avoid the possibility of accidentalimmersion of magnesium alloys in salt baths used for alumi-num.

3-2.10* Furnaces used to heat magnesium or magnesiumalloys shall be inspected and cleaned as necessary to removeany accumulation of loose iron oxide scale.

Chapter 4 Machining, Finishing, and Fabrication of Magnesium

4-1* Machining.

4-1.1 Cutting tools shall not be allowed to ride on the metalwithout cutting, as frictional heat can ignite any fine metalthat is scraped off. For the same reason, the tool shall bebacked off as soon as the cut is finished. Cutting tools shall bekept sharp and ground with sufficient rake clearance to mini-mize rubbing on the end and sides of the tool.

4-1.2* When drilling deep holes (depth greater than 5 timesdrill diameter) in magnesium, high-helix drills (45 degrees)shall be used to prevent packing of the chips produced.

4-1.3 Relief shall be maintained on tools used in grooving andparting operations, since the tool tends to rub the sides of thegroove as it cuts. Side relief shall be 5 degrees; end relief shallbe from 10 degrees to 20 degrees.

4-1.4 If lubrication is needed, as in tapping or extremely finegrooving, a high–flash point mineral oil shall be used. Water,water-soluble oils, and oils containing more than 0.2 percentfatty acids shall not be used, as they can generate flammablehydrogen gas.

Exception: Special formulated coolant fluids (water–oil emulsions)that specifically inhibit the formation of hydrogen gas shall be permit-ted.

4-1.5 Where compressed air is used as a coolant, special pre-cautions shall be taken to keep the air dry.

4-1.6 All machines shall be provided with a pan or tray tocatch chips or turnings. The pan or tray shall be installed sothat it can be readily withdrawn from the machine in case offire. It shall be readily accessible for chip removal and forapplication of extinguishing agent to control a fire.

4-1.6.1 During magnesium machining operations, chips shallbe removed from the point of generation by continuous orbatch removal. Accumulation at the point of generation shallnot exceed 3 lb (1.4 kg) dry weight. All chips shall be stored incovered noncombustible containers and removed to a storagearea in accordance with Chapter 8.

4-1.6.2 In case of a fire in the chips, the pan or tray shall beimmediately withdrawn from the machine, but shall not bepicked up or carried away until the fire has been extinguished.

4-2 Dust Collection.

4-2.1 Dust shall be collected by means of suitable hoods orenclosures at each operation. Hoods and enclosures shall beconnected either to a wet-type collector or to a cyclone collec-tor and blower located outdoors.

4-2.2 The dust collection system shall be designed andinstalled so that the dust is collected upstream of the fan.

4-2.3 The use of dry media-type collectors shall be prohib-ited.

4-2.4 Wet-Type Dust Collectors.

4-2.4.1* Where wet-type dust collectors are used, the unitshall be designed so that the dust collected is converted tosludge without contact, in the dry state, with any high-speedmoving parts.

4-2.4.2* Wet-type dust collectors shall be restricted to a dust-loading of no more than 5 grains/ ft3 (175 grains/m3) of inletair on standard configuration collectors.

4-2.4.3 Wet-type dust collectors shall be designed so that thehydrogen being generated from the magnesium contactingthe water shall be vented at all times.

4-2.4.4 Means of venting to avoid accumulation of hydrogenshall be maintained. Each chamber of the collector shall bevented to dissipate the hydrogen.

4-2.4.5 Sludge level build-up in the sludge tank of the wet-type dust collector shall not exceed 5 percent of the tank watercapacity as measured by volume. Sludge shall be removedfrom the collector whenever the collector is to remain inoper-ative for a period of 24 hours or more.

4-2.4.6 Wet-type dust collectors shall incorporate the use ofpositive venting of the sludge tank at all times during shut-down by means of an auxiliary blower that is energized whenthe main exhaust fan is turned off. The auxiliary fan volumeshall not be less than 10 percent of the exhaust fan volume.

4-2.4.7 Down-draft bench configuration separators shallmaintain no less than 300 ft/min (90 m/min) average work-surface capture velocity at each work station. Work-surface

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MACHINING, FINISHING, AND FABRICATION OF MAGNESIUM 480–7

capture velocity shall be determined as a function of nominalwork surface area.

4-2.4.8* Each wet-type dust collector shall be dedicated to thecollection of magnesium or magnesium alloy only.

4-2.5 Cyclone Dust Collectors.

4-2.5.1 Hoods and enclosures shall be connected to a high-efficiency cyclone(s) and blower located outdoors.

4-2.5.2 The cyclone exhaust shall terminate in a safe, outdoorlocation. Recycling of air from any dust collector into build-ings shall be prohibited.

4-2.5.3 All components of a dust collection system shall bemade of conductive materials and shall be watertight.

4-2.5.4 The minimum length of duct from the dust-produc-ing operation(s) to the cyclone shall be 15 ft (4.6 m).

4-2.5.5* Explosion venting shall be permitted to be installedon dry-type dust collection systems.

4-2.6 Ductwork.

4-2.6.1 The discharge duct for wet-type dust collection equip-ment shall terminate at a safe, outdoor location. Recycling ofair from any dust collector into buildings shall be prohibited.

4-2.6.2 The ductwork and fan system shall be designed suchthat the concentration of magnesium dust in the system is lessthan 25 percent of the minimum explosible concentration(MEC). In systems that involve multiple machines connectedto one dust collector, the concentration limit and velocityrequirement shall be met throughout the entire system.

4-2.6.3 All components of the dust collection system shall beof conductive material. Connecting ducts or suction tubesbetween points of collection and separators shall be com-pletely bonded and grounded. Ducts and tubes shall be asshort as possible, with no unnecessary bends. Ducts shall befabricated and installed in accordance with NFPA 91, Standardfor Exhaust Systems for Air Conveying of Materials. Ducts shall haveno unused capped connections to the main trunk line wheremagnesium dust can accumulate.

4-2.6.4 The power supply to the dust-producing equipmentshall be interlocked with the airflow from the exhaust blowerand the liquid level controller of the wet-type dust collector sothat improper functioning of the dust collection system willshut down the equipment it serves. A time-delay switch orequivalent device shall be provided on the dust-producingequipment to prevent starting of its motor drive until the sep-arator is in complete operation.

4-3 Cleaning.

4-3.1 Systematic cleaning of the entire grinding area, includ-ing roof members, pipes, conduits, et cetera, shall be carriedout daily or as often as conditions warrant.

4-3.2 Cleaning shall be done using soft brushes and conduc-tive nonsparking scoops and containers.

4-3.3* Vacuum cleaners shall not be used unless they are spe-cifically listed for use with magnesium powder or dusts.

4-4 Electrical Equipment.

4-4.1* All areas containing dust-producing machines includ-ing areas containing dust collection equipment shall be classi-fied in accordance with Article 500 of NFPA 70, NationalElectrical Code.

4-4.2 All electrical equipment shall be inspected and cleanedperiodically.

4-4.3 Where flashlights or storage battery–operated lanternsare used, they shall be listed for classified locations.

4-5* Grounding of Equipment. All equipment shall besecurely grounded by permanent ground wires to preventaccumulation of static electricity.

4-6 Safety Precautions.

4-6.1 Operator clothing shall be flame-retardant, easilyremovable, and kept clean and dust-free. Clothing shall besmooth, allowing dust to be brushed off readily. Clothing shallhave no pockets or cuffs. Woolen, silk, or fuzzy outer clothingand shoes with exposed steel parts shall be prohibited.

4-6.2 Machinery and equipment described in Section 5-2shall not be used for processing other metals until the entiregrinder and dust-collecting system are thoroughly cleaned.The grinding wheel or belt shall be replaced prior to workon other metals.

4-6.3* No open flames, electric or gas cutting or welding, orother spark-producing operations shall be permitted in thesection of the building where magnesium dust is produced orhandled while dust-producing equipment is in operation. Insuch areas where this type of work is done, all machinery shallbe shut down, and the area shall be thoroughly cleaned toremove all accumulations of magnesium dust. All internal sec-tions of grinding equipment, ducts, and dust collectors shallbe completely free of moist or dry magnesium dust, and anyhydrogen shall be flushed out. Hotwork operations in facilitiescovered by this standard shall comply with the requirements ofNFPA 51B, Standard for Fire Prevention in Use of Cutting and Weld-ing Processes.

4-6.4* Wheels used for grinding magnesium castings shall berelocated for dressing.

Exception: If it is not feasible to move the grinding wheels to a saferlocation for dressing, the hoods shall be thoroughly cleaned or removedentirely before dressing operations are started, and all deposits of duston and around the wheel shall be removed before, during, and afterdressing.

4-6.5 Nonsparking tools shall be used when making repairs oradjustments around grinding wheels, hoods, or collector unitswhere magnesium dust is present.

4-6.6 Dust collection equipment shall not have filters or otherobstructions that will allow accumulation of magnesium dust.

4-7 Drawing, Spinning, and Stamping.

4-7.1 Reliable means to prevent overheating shall be providedwhere heating magnesium for drawing or spinning.

4-7.2 Clippings and trimmings shall be collected at frequentintervals and placed in clean, dry steel or other noncombusti-ble containers. Fine particles shall be handled according tothe requirements of Chapter 5.

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480–8 STORAGE, HANDLING, AND PROCESSING OF MAGNESIUM SOLIDS AND POWDERS

Chapter 5 Magnesium Powder — Machineryand Operations

5-1 General Precautions.

5-1.1 In powder handling or manufacturing buildings and inthe operation of dust-conveying systems, every precautionshall be taken to avoid the production of sparks from staticelectricity, electrical faults, friction, or impact (e.g., iron orsteel articles on stones, on each other, or on concrete).

5-1.2 Water leakage within or into any building where it cancontact magnesium powder shall be prevented to avoid possi-ble spontaneous heating and hydrogen generation.

5-1.3 Electrical heating of any resistance element or load to ahigh temperature in an area containing a dust hazard shall beprohibited.

5-1.4* Frictional heating shall be minimized by the use oflubrication, inspection programs, and maintenance programsand techniques recommended by the equipment manufac-turer.

5-2 Requirements for Machinery.

5-2.1 All combustible magnesium dust-producing machinesand conveyors shall be designed, constructed, and operated sothat fugitive dust is minimized.

5-2.2* All machinery shall be bonded and grounded to mini-mize accumulation of static electric charge. This requirementshall be applicable to stamp mortars, mills, fans, and conveyorsin all areas where dust is produced or handled. Static-conduc-tive belts shall be used on belt-driven equipment.

5-2.3* Grounded and bonded bearings, properly sealedagainst dust, shall be used.

5-2.4 Internal machine clearances shall be maintained to pre-vent internal rubbing or jamming.

5-2.5 High-strength permanent magnetic separators, pneu-matic separators, or screens shall be installed ahead of mills,stamps, or pulverizers wherever there is any possibility thattramp metal or other foreign objects can be introduced intothe manufacturing operations.

5-3 Start-Up Operations. All the machine processing contactareas shall be thoroughly cleaned and free from water beforebeing charged with metal and placed into operation.

5-4 Charging and Discharging.

5-4.1 All magnesium powder containers not used for shippinginto or out of the plant shall be made of metal.

5-4.2 Where charging magnesium powders to (or dischargingfrom) machines, the containers shall be bonded to the equip-ment and grounded by a suitable grounding conductor.

5-5 Packaging and Storage. Magnesium powder shall bestored in steel drums or other closed conductive containers.The containers shall be tightly sealed and stored in a dry loca-tion until ready for shipment or repacking.

Chapter 6 In-Plant Conveying of Magnesium Powder

6-1 Containers.

6-1.1 Transfer of powders in-plant shall be done in coveredconductive containers, as described in Chapter 5. Specialattention shall be necessary to ensure the magnesium powderis not exposed to moisture.

6-1.2 Powered industrial trucks shall be selected in accor-dance with NFPA 505, Fire Safety Standard for Powered IndustrialTrucks Including Type Designations, Areas of Use, Conversions,Maintenance, and Operation.

6-1.3 All wheeled containers, hand trucks, and lift trucks shallbe grounded.

6-2 Pneumatic Conveying.

6-2.1 If the conveying gas is air, the magnesium dust-to-airratio throughout the conveying system shall be held safelybelow the minimum explosible concentration (MEC) of themagnesium dust at normal operating conditions. (See Section 4-2 and Appendix B.)

6-2.2* Inert gas conveying systems shall be permitted, ifdesigned in accordance with Chapter 2 of NFPA 69, Standardon Explosion Prevention Systems.

6-2.3 The inert gas used shall be based on such gases as argon,carbon dioxide, helium, nitrogen, or flue gas, and shall have alimiting oxygen concentration (LOC) determined by test tobe appropriate to the inerting gas.

6-2.4 The conveying gas shall have a dew point such that nofree moisture can condense or accumulate at any point in thesystem.

6-2.5* A minimum conveying velocity of 3500 ft/min (1068m/min) shall be maintained throughout the conveying systemto prevent the accumulation of dust at any point and to pickup any dust or powder that can drop out during an unsched-uled system stoppage.

6-3 Ductwork for Conveying Systems.

6-3.1* Deflagration venting (e.g., rupture diaphragms) shallbe provided on ductwork. Deflagration vents shall relieve to asafe location outside of the building.

Exception: Ductwork provided with explosion isolation systems iden-tified in NFPA 69, Standard on Explosion Prevention Systems, whichcan prevent propagation of a deflagration into other parts of the pro-cess.

6-3.2* Wherever damage to other property or injury to per-sonnel can result from the rupture of the ductwork, and whereexplosion relief vents cannot provide sufficient pressure relief,the ductwork shall be designed to withstand a sudden internalpressure of 125 psi (862 kPa).

Exception: If a portion of the ductwork is so located that no damage toproperty or injury to personnel can result from its bursting, that por-tion shall be permitted to be of light construction so as to intentionallyfail, thereby acting as an auxiliary explosion vent for the system.

6-3.3 Conveyor ducts shall be constructed of conductive mate-rial. Nonconductive duct liners shall not be used.

6-3.4* Ducts shall be electrically bonded and grounded tominimize accumulation of static electric charge. See 5-2.2.

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6-3.5 Where the conveying duct is exposed to weather ormoisture, it shall be moisture tight.

6-4 Fan Construction and Arrangement.

6-4.1* Blades and housings of fans used to move air or inertgas in conveying ducts shall be constructed of conductive,nonsparking metal, such as bronze, nonmagnetic stainlesssteel, or aluminum.

6-4.2 Personnel shall not be permitted within 50 ft (15 m) ofthe fan while it is operating. No maintenance shall be per-formed on the fan until it is shut down.

Exception: If personnel must approach the fan while it is operating,such as for a pressure test, it shall be done under the direct supervisionof a competent technical person and with the knowledge and approvalof operating management.

6-4.3 Fans shall be located outside of all buildings and locatedso that entrance of dust from the fan exhaust into any buildingshall be minimized.

6-4.4 Fans shall be electrically interlocked with dust-produc-ing machinery so that the machines shut down if the fans stop.

6-5 Dust Collectors.

6-5.1 Dry dust collectors shall be located outside, in a safelocation, and shall be provided with barriers or other meansfor protection of personnel.

6-5.2 The area around the collector shall be posted with thefollowing:

CAUTION: This dust collector can contain explosibledust. Keep outside the marked area while equipment isoperating.

6-5.3 Ductwork shall comply with the provisions of Section6-3.

6-5.4* The entire dust collection system, including the dustcollector, shall be constructed of conductive material andshall be completely bonded and grounded to minimize accu-mulation of static electric charge.

6-5.5* Dry dust collectors where an explosion hazard existsshall be provided with deflagration vents. Extreme care shallbe taken in the selection of the type and location of vents orweak sections of the collector to minimize injury to personneland blast damage to nearby equipment or structures. Defla-gration vents shall be positioned so that a potential blast shallnot be directed toward any combustible or frangible structure.

6-5.6 Where repairs on dry dust collectors are necessary, thecollectors shall be emptied and residual accumulations of dustthoroughly removed. (See Section 5-2.) Ductwork leading intothe collector shall be disconnected and blanked off beforerepair work shall be permitted to be started.

Chapter 7 Prevention of Fugitive Dust Accumulations

7-1 General.

7-1.1 Dust shall not be permitted to accumulate. Spills shallbe removed at once, using conductive, nonsparking scoopsand soft brooms or brushes having natural fiber bristles. Com-pressed-air blowdown shall not be permitted.

7-1.2* Vacuum Cleaning Systems.

7-1.2.1 Vacuum cleaning systems shall be used only forremoval of dust accumulations too small, too dispersed, or tooinaccessible to be thoroughly removed by hand-brushing.

7-1.2.2* Vacuum cleaning systems shall be effectively bondedand grounded to minimize accumulation of static electriccharge.

7-1.2.3 Due to the inherent hazards associated with the use offixed and portable vacuum cleaning systems for finely dividedcombustible magnesium dust, special engineering consider-ations shall be given to the design, installation, maintenance,and use of such systems.

7-1.2.4* Portable vacuum cleaners shall be used only if listedor approved for use with combustible magnesium dust.

7-1.2.5 Vacuum cleaner hose shall be conductive and nozzlesor fittings shall be made of conductive, nonsparking material.Assembled components shall be conductive and bondedwhere necessary. Periodic tests for continuity shall be per-formed.

7-1.2.6 Combustible magnesium dust picked up by a fixed vac-uum cleaning system shall be discharged into a container orcollector located outside the building.

7-2 Cleaning Frequency.

7-2.1* Operating personnel and supervisors shall exercisegreat care to prevent the accumulation of excessive dust onany portions of buildings or machinery not regularly cleanedduring daily operations.

7-2.2 Regular periodic cleaning, with all machinery idle andpower off, shall be performed as frequently as conditionswarrant.

Chapter 8 Storage of Magnesium Solids

8-1* Storage of Pigs, Ingots, and Billets.

8-1.1 The size of piles shall be limited. Minimum aisle widthsshall be based on the height of the pile as per 8-1.2.4. The pileheight shall not exceed 20 ft (6.1 m).

8-1.2 Yard (Outdoor) Storage.

8-1.2.1 Magnesium ingots shall be carefully piled on firm andgenerally level areas to prevent tilting or toppling. Storageareas and yard pavements shall be well drained. The storagearea shall be kept free of grass, weeds, and accumulations ofcombustible materials.

8-1.2.2 Combustible flooring or supports shall not be usedunder piles of ingots.

8-1.2.3 The quantity of magnesium stored in any pile shall bekept to a minimum. In no case shall the amount exceed100,000 lb (45,400 kg).

Exception: Quantities stored shall be permitted to be increased up to amaximum of 1,000,000 lb (454,000 kg) per pile when the followingrequirements are met:

a) Provision shall be made for drainage of water away from storedmaterial.

(b) The aisle widths shall be equal to the pile height plus 10 ft (3 m),but no less than 15 ft (4.5 m).

(c) Piles shall not be more than 10 ft wide.

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8-1.2.4 Aisle width shall be at least one-half the height of thepiles and shall be at least 10 ft (3 m).

8-1.2.5 Readily combustible material shall not be storedwithin a distance of 25 ft (7.6 m) from any pile of magnesiumingots.

8-1.2.6 An open space, equal to the height of the piles plus 10ft (3 m), shall be provided between the stored magnesiumingots and adjoining property lines where combustible mate-rial or buildings are exposed or where the adjacent occupancycan provide fire exposure to the magnesium.

8-1.3* Indoor Storage.

8-1.3.1 Storage shall be in buildings of noncombustible con-struction.

8-1.3.2 Floors shall be well drained to prevent accumulationsof water in puddles.

8-1.3.3 Supports and pallets used under piles of magnesiumingots shall be noncombustible.

8-1.3.4 The quantity of magnesium ingots stored in any onepile shall be kept to a minimum, but in no case shall theamount exceed 50,000 lb (23,000 kg).

Exception: Quantities stored shall be permitted to be increased up to amaximum of 500,000 lb (226,800 kg) per pile when the following re-quirements are met:

(a) Piles shall not be more than 10 ft (3 m) wide.(b) *The building shall be sprinklered if combustible materials are

stored without the benefit of separation by fire wall or fire barrier wallfrom the magnesium storage.

8-1.3.5 Aisle widths shall comply with 8-1.2.4.

8-1.3.6 Combustible material shall not be stored within a dis-tance of 25 ft (7.6 m) from any pile of magnesium pigs, ingots,and billets.

8-2 Storage of Heavy Castings.

8-2.1 Buildings used for the storage of heavy magnesium cast-ings shall be of noncombustible construction.

Exception: Storage shall be permitted in buildings of combustible con-struction if the buildings are fully protected by an automatic sprinklersystem.

8-2.2* Floors shall be of noncombustible construction andshall be well drained to prevent accumulations of water inpuddles.

8-2.3 All magnesium castings shall be clean and free of chipsor fine particles of magnesium when being stored.

8-2.4 The size of storage piles of heavy magnesium castings,either in cartons or crates or free of any packing material, shallbe limited to 1250 ft3(36 m3). Aisles shall be maintained topermit inspection and effective use of fire protection equip-ment.

8-2.5 Aisle width shall be at least one-half the height of thepiles and shall be at least 10 ft (3 m).

8-2.6* Automatic sprinkler protection shall be permitted tobe installed in magnesium storage buildings where combusti-ble cartons, crates, or other packing materials are present.

8-3 Storage of Light Castings.

8-3.1 Light magnesium castings shall be stored in noncom-bustible buildings and shall be segregated from other storage.

Exception: Storage of light castings shall be permitted in buildings ofcombustible construction if the buildings are fully protected by an au-tomatic sprinkler system. (See 8-3.4.)

8-3.2 Piles of stored light magnesium castings, either in car-tons or crates or without packing, shall be limited in size to1000 ft3 (28 m3). Light castings shall be segregated from othercombustible materials and kept away from flames or sources ofheat capable of causing ignition.

8-3.3 Aisle widths shall be at least one-half the height of thepiles and shall be at least 10 ft (3 m).

8-3.4* Automatic sprinkler protection shall be permitted tobe installed in magnesium storage buildings where combusti-ble cartons, crates, or packing materials are present.

8-4 Storage in Racks or Bins.

8-4.1 Racks shall be permitted to be extended along walls inoptional lengths. Aisle spaces in front of racks shall be equalto the height of the racks. All aisle spaces shall be kept clear.

8-4.2 Combustible rubbish, spare crates, and separators shallnot be permitted to accumulate within the rack space. Separa-tors and metal sheets shall not be stacked on edge, and leanedagainst racks, as they will prevent heat from a small fire fromactivating automatic sprinklers and will act as shields againstsprinkler discharge.

8-5 Storage of Scrap Magnesium.

8-5.1 This section shall apply to the storage of scrap magne-sium in the form of solids, chips, turnings, swarf, or other fineparticles.

8-5.2 Buildings used for the indoor storage of magnesiumscrap shall be of noncombustible construction.

8-5.3 Dry magnesium scraps shall be kept well separated fromother combustible materials. Scraps shall be kept in coveredsteel or other noncombustible containers and shall be kept insuch manner or locations that they will not become wet. Out-side storage of magnesium fines shall be permitted if such stor-age is separated from buildings or personnel and great care isexercised so as to avoid the fines becoming wet.

8-5.4* Wet magnesium scrap (chips, fines, swarf, or sludge)shall be kept under water in a covered and vented steel con-tainer at an outside location. Sources of ignition shall be keptaway from the drum vent and top. Containers shall not bestacked.

8-5.5* Storage of dry scrap in quantities greater than 50 ft3

(1.4 m3) [which is six 55-gal drums (six 208-L drums)] shall bekept separate from other occupancies by fire-resistive con-struction without window openings or by an open space of atleast 50 ft (15 m). Such buildings shall be well-ventilated toavoid the accumulation of hydrogen in the event that thescrap becomes wet.

8-5.6 Solid magnesium scrap, such as clippings and castings,shall be stored in noncombustible bins or containers pendingsalvage.

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8-5.7 Oily rags, packing materials, and similar combustiblesshall be permitted in storage bins or areas that store solid mag-nesium scrap.

8-5.8 The use of automatic sprinklers in magnesium scrapstorage buildings or areas shall be prohibited.

8-5.9 Fire extinguishing agents compatible for the hazardspresent shall be readily available in magnesium scrap storageareas.

8-6 Storage of Magnesium Powder.

8-6.1 Buildings used to store magnesium powder shall be ofnoncombustible single-story construction.

8-6.2 The use of automatic sprinklers in magnesium powderstorage buildings shall be strictly prohibited.

8-6.3 Magnesium powder shall be kept well separated fromother combustible or reactive metals.

8-6.4 Magnesium powder shall be stored in closed steel drumsor other closed noncombustible containers. The containersshall be stored in dry locations.

8-6.5 Magnesium powder storage areas shall be kept dry andchecked for water leakage.

8-6.6* All areas used for the storage of magnesium powdershall be classified in accordance with Article 500 of NFPA 70,National Electrical Code.

8-6.7 Fire extinguishing agents compatible for the hazardspresent shall be readily available in magnesium powder stor-age areas.

8-6.8 Where magnesium powder in drums is stacked for stor-age, the maximum height shall not exceed 18 ft (5.5 m). Stor-age shall be stacked in a manner that ensures stability. Underno circumstances shall containers be permitted to topple over.The safest manner of storage is achieved using no stacking.

8-7 Storage of Other Magnesium Products.

8-7.1* This section shall apply to the storage of parts and com-ponents, in warehouses, wholesale facilities, factories, andretail establishments, in which magnesium makes up 50 per-cent or more of the article’s composition on a volumetricbasis, or where the magnesium-containing assemblies as pack-aged or stored exhibit the burning characteristics of magne-sium.

8-7.2 Storage in quantities greater than 50 ft3 (1.4 m3) shall beseparated from storage of other materials that are either com-bustible or in combustible containers by aisles with a mini-mum width equal to the height of the piles of magnesiumproducts.

8-7.3 Magnesium products stored in quantities greater than1000 ft3 (28 m3) shall be separated into piles each not largerthan 1000 ft3 (28 m3), with the minimum aisle width equal tothe height of the piles but in no case less than 8 ft (3 m).

8-7.4* The storage area shall be protected by automatic sprin-klers in any of the following situations:

(a) Where storage in quantities greater than 1000 ft3 (28 m3)is contained in a building of combustible construction

(b) Where magnesium products are packed in combustiblecrates or cartons

(c) Where there is other combustible storage within 30 ft (9m) of the magnesium

Chapter 9 Fire Prevention and Fire Protection

9-1 Fire Prevention. The provisions of Chapter 9 shall apply toall magnesium production processes, handling, and storageoperations.

9-1.1 Buildings shall comply with the applicable provisions ofNFPA 101, Life Safety Code.

9-1.2* Hotwork permits shall be required in designated areasthat contain exposed magnesium chips, powder, or sponge.All hotwork areas that require a permit shall be thoroughlycleaned of magnesium chips, powder, or sponge before hot-work is performed.

9-1.3* All containers used to receive molten magnesium shallbe cleaned and dried thoroughly before use.

9-1.4 Good housekeeping practices shall be maintained. Sup-plies shall be stored in an orderly manner with properly main-tained aisles to allow routine inspection and segregation ofincompatible materials. Supplies of materials in magnesiumprocessing areas shall be limited to those amounts necessaryfor normal operation.

9-1.5 Ordinary combustible materials, such as paper, wood,cartons, and packing material, shall not be stored or allowedto accumulate in magnesium processing areas.

Exception: This requirement shall not apply where ordinary combus-tible materials are necessary for the process and are stored in designatedareas.

9-1.6* Periodic cleaning of magnesium chips or powder frombuildings and machinery shall be carried out as frequently asconditions warrant. Chips or powder shall be removed to asafe storage or disposal area.

9-1.7 Periodic inspections shall be conducted, as frequentlyas conditions warrant, to detect the accumulation of excessivemagnesium chips or powder on any portions of buildings ormachinery not regularly cleaned during daily operations.Records of these inspections shall be kept.

9-1.8* Ordinary combustible materials shall not be discardedin containers used for the collection of sponge, chips, or pow-der.

Exception: Floor sweepings from magnesium operations shall be per-mitted to contain small amounts of ordinary combustible materials.

9-1.9 Areas in which flammable and combustible liquids areused shall be in accordance with the requirements of NFPA30, Flammable and Combustible Liquids Code.

9-1.10 Smoking shall not be permitted in areas where ignit-able magnesium chips or powder is present. Such areas shallbe posted with “no smoking” signs.

Exception: Where smoking is prohibited throughout the entire plant,the use of signage shall be at the discretion of the facility management.

9-1.11 All electrical equipment and wiring in magnesium pro-duction, processing, handling, and storage facilities shall com-ply with NFPA 70, National Electrical Code.

9-1.12 Where using tools and utensils in areas handling mag-nesium powder, consideration shall be given to the risks asso-ciated with generating impact sparks and static electricity.

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480–12 STORAGE, HANDLING, AND PROCESSING OF MAGNESIUM SOLIDS AND POWDERS

9-1.13* Processing equipment used in magnesium operationsshall be electrically bonded and grounded properly in orderto prevent accumulations of static electricity.

9-1.14 Where magnesium is collected or stored in containers,material-handling equipment with sufficient capability toremove any container from the immediate area in the case ofan emergency shall be readily available.

9-2* General Fire Protection.

9-2.1 A fire protection plan shall be provided for all areaswhere magnesium is present.

9-2.2* Buildings or portions of buildings of noncombustibleconstruction principally used for magnesium storage or han-dling shall not be permitted to be equipped with automaticsprinkler protection.

Exception: Sprinkler systems installed in accordance with NFPA 13,Standard for the Installation of Sprinkler Systems, shall be permittedin areas where combustibles other than magnesium create a more severehazard than the magnesium and where acceptable to an authority hav-ing jurisdiction that is knowledgeable of the hazards associated withmagnesium.

9-2.3 If required by the authority having jurisdiction, auto-matic sprinkler protection, installed in accordance with NFPA13, Standard for the Installation of Sprinkler Systems, shall be pro-vided for offices, repair shops, and warehouses not used forthe storage of magnesium powder or chips.

9-2.4 As an alternative, a specially engineered fire protectionsystem specifically designed to be compatible with the hazardspresent in the magnesium operation area shall be permittedto be installed in areas where combustible loading is essentialto the process operation.

9-2.5 Fire-Fighting Organization. Any fire-fighting organiza-tions that respond to an emergency shall be trained in the haz-ards involved in fighting a magnesium fire.

9-3 Extinguishing Agents and Application Techniques.

9-3.1* Only listed or approved Class D extinguishing agentsor those tested and shown to be effective for extinguishingmagnesium fires shall be permitted. A supply of extinguishingagent for manual application shall be kept within easy reach ofpersonnel while they are working with magnesium. The quan-tity of extinguishing agent shall be sufficient to contain antic-ipated fires.

9-3.2* The use of pressurized extinguishing agents shall notbe permitted on a magnesium powder or chip fire, unlessapplied carefully so as not to disturb or spread the magnesiumpowder. This shall be performed only by trained personnelbecause of the danger of spreading the burning powder orchips or creating a dust cloud. The bulk dry extinguishingagents shall be provided in areas where chips and powders areproduced or used. The bulk dry extinguishing agents shall bekept dry (i.e., free of moisture).

9-3.3 Extinguishing agents intended for manual applicationshall be kept in identified containers. Container lids shall besecured in place to prevent agent contamination and to keepthe agent free of moisture. Where large quantities of agent areexpected to be needed, a clean, dry shovel shall be providedwith the container. Where small amounts are needed, a handscoop shall be provided with each container.

9-3.4 Portable or wheeled extinguishers approved for use onmagnesium fires shall be permitted and shall be distributed inaccordance with NFPA 10, Standard for Portable Fire Extinguish-ers.

9-3.5* Only A:B:C or B:C, dry chemical portable fire extin-guishers shall be provided in accordance with NFPA 10, Stan-dard for Portable Fire Extinguishers, to be used on other classes offires in areas where solid magnesium is present. Water-basedor CO2 extinguishers shall not be provided in areas containingmagnesium chips or powder.

Exception: CO2 extinguishers shall be permitted in areas containingmagnesium for use on electrical fires. Such CO2 extinguishers shall beclearly marked “Not for use on magnesium fires.”

9-3.6* Dry sodium chloride, or other dry chemicals or com-pounds suitable for extinguishment or containment of magne-sium fires, shall be permitted to be substituted for Class D fireextinguishers. These alternative agents shall be stored in a man-ner that ensures the agent’s effectiveness. Shovels or scoopsshall be kept readily available adjacent to the containers. Allextinguishing agent storage areas shall be clearly identified.

9-3.7 Magnesium fines shall be segregated by storage in non-combustible drums.

9-3.8* Where a fire occurs in processing equipment, materialfeed to the equipment shall be stopped. When feed is stopped,the equipment shall be kept in operation.

Exception: Where continued operation of equipment would cause thespread of fire, it shall be stopped.

Chapter 10 Referenced Publications

10-1 The following documents or portions thereof are refer-enced within this standard as mandatory requirements andshall be considered part of the requirements of this standard.The edition indicated for each referenced mandatory docu-ment is the current edition as of the date of the NFPA issuanceof this standard. Some of these mandatory documents mightalso be referenced in this standard for specific informationalpurposes and, therefore, are also listed in Appendix D.

10-1.1 NFPA Publications. National Fire Protection Associa-tion, 1 Batterymarch Park, P.O. Box 9101, Quincy, MA 02269-9101.

NFPA 10, Standard for Portable Fire Extinguishers, 1998 edition.NFPA 13, Standard for the Installation of Sprinkler Systems,

1996 edition.NFPA 30, Flammable and Combustible Liquids Code, 1996 edi-

tion.NFPA 51B, Standard for Fire Prevention in Use of Cutting and

Welding Processes, 1994 edition.NFPA 69, Standard on Explosion Prevention Systems, 1997 edi-

tion.NFPA 70, National Electrical Code®, 1999 edition.NFPA 80, Standard for Fire Doors and Fire Windows, 1995 edi-

tion.NFPA 86, Standard for Ovens and Furnaces, 1995 edition.NFPA 91, Standard for Exhaust Systems for Air Conveying of

Materials, 1995 edition.NFPA 101®, Life Safety Code®, 1997 edition.NFPA 220, Standard on Types of Building Construction, 1995

edition.

1998 Edition

APPENDIX A 480–13

NFPA 505, Fire Safety Standard for Powered Industrial TrucksIncluding Type Designations, Areas of Use, Conversions, Mainte-nance, and Operation, 1996 edition.

NFPA 650, Standard for Pneumatic Conveying Systems for Han-dling Combustible Particulate Solids, 1998 edition.

NFPA 651, Standard for the Machining and Finishing of Alumi-num and the Production and Handling of Aluminum Powders, 1998edition.

10-1.2 ASTM Publication. American Society for Testing andMaterials, 100 Barr Harbor Drive, West Conshohocken, PA19428-2959.

ASTM E 136, Standard Test Method for Behavior of Materials ina Vertical Tube Furnace at 750°C, 1992 edition.

Appendix A Explanatory Material

Appendix A is not a part of the requirements of this NFPA docu-ment but is included for informational purposes only. This appendixcontains explanatory material, numbered to correspond with the appli-cable text paragraphs.

A-1-1.4 Transportation Regulations. Regulations for thedomestic shipment of dangerous goods (magnesium powderis so classified) are issued by the U.S. Department of Transpor-tation (49 CFR, Parts 100-199), which has specific responsibil-ity for promulgating the regulations. These regulations areupdated and published yearly by the DOT. International ship-ments are regulated by the United Nations, International AirTransport Association, International Maritime Organization,and other national agencies. Attention is directed to activitynow underway to consolidate the regulations under auspicesof the United Nations.

A-1-4 Approved. The National Fire Protection Associationdoes not approve, inspect, or certify any installations, proce-dures, equipment, or materials; nor does it approve or evalu-ate testing laboratories. In determining the acceptability ofinstallations, procedures, equipment, or materials, the author-ity having jurisdiction may base acceptance on compliancewith NFPA or other appropriate standards. In the absence ofsuch standards, said authority may require evidence of properinstallation, procedure, or use. The authority having jurisdic-tion may also refer to the listings or labeling practices of anorganization that is concerned with product evaluations and isthus in a position to determine compliance with appropriatestandards for the current production of listed items.

A-1-4 Authority Having Jurisdiction. The phrase “authorityhaving jurisdiction” is used in NFPA documents in a broadmanner, since jurisdictions and approval agencies vary, as dotheir responsibilities. Where public safety is primary, theauthority having jurisdiction may be a federal, state, local, orother regional department or individual such as a fire chief;fire marshal; chief of a fire prevention bureau, labor depart-ment, or health department; building official; electricalinspector; or others having statutory authority. For insurancepurposes, an insurance inspection department, rating bureau,or other insurance company representative may be the author-ity having jurisdiction. In many circumstances, the propertyowner or his or her designated agent assumes the role of theauthority having jurisdiction; at government installations, thecommanding officer or departmental official may be theauthority having jurisdiction.

A-1-4 Listed. The means for identifying listed equipmentmay vary for each organization concerned with product evalu-ation; some organizations do not recognize equipment aslisted unless it is also labeled. The authority having jurisdictionshould utilize the system employed by the listing organizationto identify a listed product.

A-2-4.3 See NFPA 68, Guide for Venting of Deflagrations.

A-2-5 See NFPA 77, Recommended Practice on Static Electricity.

A-2-6.2 See NFPA 499, Recommended Practice for the Classificationof Combustible Dusts and of Hazardous (Classified) Locations forElectrical Installations in Chemical Process Areas.

A-3-1 Chips, turnings, powders, or swarf that is being pre-heated or charged to melting pots will autoignite at tempera-tures below that of the solid metal. Solids should be free ofthese smaller particles, as they can ignite and, in turn, ignitethe solids. There should be no depression directly beneath themagnesium storage area where water can accumulate or flowduring a fire.

A-3-1.2 The contact of moisture with molten magnesium metalcan result in a violent explosive reaction with the generationof steam or hydrogen. It is important to establish and documenta method of preheating that heats all material to a minimumtemperature of 250°F (121°C) to ensure the removal of mois-ture. A higher heating temperature might be necessary if themetal is contaminated with corrosion products, salts, or otherforeign materials. Molds or tools that will come into contactwith molten magnesium should be similarly preheated.

A-3-1.4 Iron scale and molten magnesium can create a ther-mite reaction. The interior of a crucible furnace normallyknown as the “setting” is a critical area of concern. With theuse of SF6 and other protective atmospheres, the problem ofiron scale forming above the melt and reacting if it falls intothe melt is a concern. Since concrete always contains water,concrete in contact with hot materials such as molten magne-sium can result in an extremely violent reaction, including vio-lent spalling of concrete.

A-3-2 Heat-treating of magnesium has associated fire risks. Toretard ignition of magnesium, mixtures of sulfur dioxide(SO2), sulfur hexafluoride with carbon dioxide (SF6/CO2),helium(He), and argon (Ar) with air is recommended in heat-treating furnaces operating above 750°F (399°C).

A-3-2.2 See NFPA 86, Standard for Ovens and Furnaces.

A-3-2.6 Extreme care should be taken when heat treating alu-minum that contains magnesium alloys since aluminum addi-tions form a eutectic alloy with considerably lower melting andautoignition temperatures. Failure to identify the alloy canresult in heat-treating furnace fires. Having magnesium inphysical contact with aluminum at an elevated temperaturecan produce the same effect.

A-3-2.8 Heating magnesium in the presence of oxidizers canresult in combustion. Special salt fluxes can be safely used fordip-brazing of magnesium.

A-3-2.9 Magnesium and aluminum form a eutectic alloy withconsiderably lower melting temperatures and autoignitiontemperatures than either parent metal.

A-3-2.10 There is a potential for a thermite reaction betweenmagnesium, magnesium alloys, and iron oxide at elevatedtemperatures.

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480–14 STORAGE, HANDLING, AND PROCESSING OF MAGNESIUM SOLIDS AND POWDERS

A-4-1 Flashing of chips during machining should be mini-mized by any of the following methods:

(a) Keep surface speed below 300 ft/min (1.5 m/sec) orabove 2200 ft/min (11 m/sec).

(b) Increase feed rate from 0.0008 in. to 0.010 in. (0.02 mm to0.25 mm) per revolution.

(c) Control relative humidity in the machining area to 45 per-cent or lower at 70°F (21°C) room temperature.

(d) Apply a coolant.

A-4-1.2 Use of high-helix drills prevents frictional heat andpossible flash fires in fines. High-helix drills are also recom-mended for drilling deep holes through composite or sand-wich sections.

A-4-2.4.1 Interaction between magnesium and aluminum alloyfines (if the aluminum contains more than 1/2 to 1 percent cop-per) in wet collector sludge can lead to hydrogen evolution andheat generation greatly exceeding that produced by magnesiumfines alone. See NFPA 651, Standard for the Machining and Finish-ing of Aluminum and the Production and Handling of Aluminum Pow-ders. See Figures A-4-2.4.1(a), A-4-2.4.1(b), and A-4-2-4.1(c).

A-4-2.4.2 See the table on Range of Particle Size, Concentration,and Collector Performance in “Industrial Ventilation: A Manualof Recommended Practice.” One pound is equivalent to 7000grains. The maximum concentration of less than 100 mesh mag-nesium dust should never exceed 0.03 oz/ft3 (0.03 g/L) of (air),which is the minimum explosible concentration (MEC).

Minimum explosible concentrations for magnesium dust inair are published in BOM, RI 6516, “Explosibility of Metal Pow-ders.” Although the metal dust-air suspension normally can beheld below the minimum explosible concentration (MEC) inthe conveying system, the suspension can pass through theflammable range in the collector at the end of the system.

A-4-2.4.8 Interaction between magnesium and aluminumalloy fines (if the aluminum contains more than 1/2 to 1 per-cent copper) in wet collector sludge can lead to hydrogen evo-lution and heat generation greatly exceeding that producedby magnesium fines alone. See NFPA 651, Standard for theMachining and Finishing of Aluminum and the Production andHandling of Aluminum Powders.

A-4-2.5.5 See NFPA 68, Guide for Venting of Deflagrations, forguidance on explosion venting.

A-4-3.3 Standard commercial industrial vacuum cleanersshould not be used, as they are not safe for use with magnesium.

Figure A-4-2.4.1(a) Typical liquid precipitation separator for fixed dust-producing equipment.

Dust-producingequipment

Power to dust-producing

machine motorinterrupted by low

airflow or lowliquid level at theliquid precipitator

Self-openingvent (optional)

Sumpvent

Mist eliminatorpacks

Mist eliminatoraccess door

Liquid level controlwith interlock

Inspection andcleanout door

Water level

Sludge level in tank

Overflow anddrain piping

Figure A-4-2.4.1(b) Typical liquid precipitation separator for porta-ble dust-producing equipment.

Figure A-4-2.4.1(c) Diagram of five methods of precipitating dust used in precipitators.

Mist eliminatorpacks

Mist eliminatoraccess doors

Liquid levelcontrol withinterlock

Water level

Sludge levelin tank

¹⁄₂-in.(13-mm)expandedmetalaluminummesh

Nonsparkingwork surface

1998 Edition

APPENDIX A 480–15

A-4-4.1 See NFPA 499, Recommended Practice for the Classificationof Combustible Dusts and of Hazardous (Classified) Locations forElectrical Installations in Chemical Process Areas, for guidance onclassified areas for Class II materials.

A-4-5 See NFPA 77, Recommended Practice on Static Electricity.

A-4-6.3 Attention is called to the hazardous conditions thatcan exist both inside and outside the plant if cutting torchesare used to dismantle dust collectors or powder-producingmachinery before all dust accumulations have been removed.

It is a commonly recognized practice that operators of cut-ting or welding torches be required to obtain a written permitfrom the safety or fire protection officer of the plant beforeusing their equipment under any condition around magne-sium powder plants.

A-4-6.4 Special precautions are necessary to prevent ignitionswhile dressing the wheels used for grinding magnesium cast-ings. Hot metal thrown off by the dressing tool can ignite dustor magnesium deposits in the hood or duct.

A-5-1.4 Temperature-sensing elements connected to alarmsor machine stop switches can be employed for locations whereoverheating of bearings or other elements is anticipated.

A-5-2.2 See NFPA 77, Recommended Practice on Static Electricity.

A-5-2.3 Bearings located outside of the air volume containingmagnesium dust are preferred. Bearings within the air volumecontaining magnesium dust are potential sources of ignitionin the event of a failure. Bearings should be located outsidethe air volume containing magnesium dust.

A-6-2.2 Completely inert gas cannot be used as an inertingmedium, since the magnesium powder would eventually, atsome point in the process, be exposed to the atmosphere, atwhich time the unreacted surfaces would be oxidized; enoughheat would be produced to initiate either a fire or an explo-sion. To provide maximum safety, a means for the controlledoxidation of newly exposed surfaces is provided by regulatingthe oxygen concentration in the inert gas. The mixture servesto control the rate of oxidation, while materially reducing thefire and explosion hazard.

A-6-2.5 Higher conveying velocities are more desirable andincrease safety.

A-6-3.1 For information on explosion vents, see NFPA 68,Guide for Venting of Deflagrations. Ductwork vent spacing guide-lines in NFPA 68 do not apply to KSt values greater than 300bar/m-sec.

A-6-3.2 See NFPA 69, Standard on Explosion Prevention Systems.

A-6-3.4 See NFPA 77, Recommended Practice on Static Electricity.

A-6-4.1 Information on spark-resistant fans and blowers canbe found in AMCA (Air Movement and Control Association)Standard No. 99-0401-91.

A-6-5.4 See NFPA 77, Recommended Practice on Static Electricity.

A-6-5.5 Explosion venting is especially important for combus-tible magnesium dust, due to the high maximum explosionpressures reached and the extremely high rate of pressurerise. For information on design of explosion vents and predict-ing the size of the fireball, see NFPA 68, Guide for Venting ofDeflagrations. Dust collectors, when provided by a manufac-turer, seldom have properly sized venting to handle a combus-tible magnesium dust explosion.

A-7-1.2 Permanently installed vacuum cleaning systems pro-vide the maximum safety because the dust collecting deviceand the exhaust blower can be located in a safe location out-side the dust-producing area. The dust collector should belocated outside the building, preferably more than 50 ft (15m) away. If the collector is located closer than 50 ft (15 m), itis usually surrounded by a strong steel shield, cylindrical inshape and open at the top, or closed with a light, unfastenedcover. The shield is closed at the bottom and designed to with-stand a blast pressure of 200 psig (1380 kPa gauge). Such aprotective barricade will direct an explosion upward and canprotect both property and personnel. All suction lines shouldbe provided with explosion vents and anti-flashback valves.

A-7-1.2.2 See NFPA 77, Recommended Practice on Static Electricity.

A-7-1.2.4 Improper use of vacuum cleaners for magnesiumpowder accumulations can result in fire or explosion. Forinformation on static electricity, see NFPA 77, RecommendedPractice on Static Electricity.

A-7-2.1 See NFPA 499, Recommended Practice for the Classificationof Combustible Dusts and of Hazardous (Classified) Locations forElectrical Installations in Chemical Process Areas.

A-8-1 Industrial buildings or separate storage areas in whichmagnesium parts are being stored in quantities greater than500 lb (227 kg), or where these magnesium parts are the pri-mary hazard, should be labeled in accordance with NFPA 704,Standard System for the Identification of the Hazards of Materials forEmergency Response. This serves as a warning to fire fighters onthe potential risk in the event of an emergency.

A-8-1.3 Storage of magnesium ingots should be on the first orground floor. Basements or depressions below the magnesiumstorage area into which water or molten metal can flow shouldbe avoided.

A-8-1.3.4(b) See NFPA 221, Standard for Fire Walls and Fire Bar-rier Walls, for wall construction details.

A-8-2.2 Storage of magnesium castings should be on the firstor ground floor. Basements or depressions below the magne-sium cast storage area into which water or molten metal canflow should be avoided.

A-8-2.6 Sprinkler systems are of vital importance in heavymagnesium casting areas that also contain significant amountsof ordinary combustibles, as sprinkler operation can preventthe magnesium from becoming involved in the fire.

A-8-3.4 A slow-burning fire in nearby combustible materialcan develop enough heat to ignite thin-section magnesiumand produce a well-involved magnesium fire before automaticsprinklers operate. Special importance, therefore, should beattached to prompt fire detection and alarm service, design ofa fast-operating automatic sprinkler system, and avoidance ofobstructions to sprinkler discharge. See NFPA 13, Standard forthe Installation of Sprinkler Systems.

A-8-5.4 The wet magnesium should be checked frequently toensure that it remains totally immersed during storage.

Fines that come in contact with water, water-soluble oils,and oils containing more than 0.2 percent fatty acids can gen-erate flammable hydrogen gas. Fines that come in contact withanimal or vegetable oils can ignite spontaneously.

A-8-5.5 For design information, see NFPA 68, Guide for Ventingof Deflagrations.

1998 Edition

480–16 STORAGE, HANDLING, AND PROCESSING OF MAGNESIUM SOLIDS AND POWDERS

A-8-6.6 See NFPA 499, Recommended Practice for the Classificationof Combustible Dusts and of Hazardous (Classified) Locations forElectrical Installations in Chemical Process Areas.

A-8-7.1 Since the magnesium portions of parts and compo-nents can exhibit the burning characteristics of magnesiumwhen involved in a fire, storage plans and arrangementsshould be designed to mitigate the fire hazards associated withburning magnesium.

Assemblies in which magnesium is a minority componentmight or might not exhibit burning behavior similar to a fireinvolving pure magnesium, depending on the following:

(a) Whether or not the magnesium is exposed on the outsideof the assembly

(b) How fast or how completely the packaging material mightburn away to expose the magnesium

(c) Height and arrangement of the storage array

(d) Intensity of any exposure fire

(e) Rapidity with which automatic protection systems mightrespond to control the initial fire, thus preventing theinvolvement of the magnesium. The best method todetermine the level of hazard is by a properly designedfire test.

A-8-7.4 A slow-burning fire in nearby combustible materialcan develop enough heat to ignite thin-section magnesiumand produce a well-involved magnesium fire before automaticsprinklers operate. Special importance, therefore, should beattached to prompt fire detection and alarm service, design ofa fast-operating automatic sprinkler system, and avoidance ofobstructions to sprinkler discharge. See NFPA 13, Standard forthe Installation of Sprinkler Systems.

A-9-1.2 For information on cutting and welding practices, seeNFPA 51B, Standard for Fire Prevention in Use of Cutting and Weld-ing Processes.

A-9-1.3 Molten magnesium and molten magnesium chloridepresent an extremely dangerous fire and fume hazard, in addi-tion to an explosion hazard, where they come into contactwith water or residual moisture.

A-9-1.6 Consideration should be given to the potential igni-tion sources associated with the operation of cleaning and pro-cessing equipment during the cleaning operation.

A-9-1.8 Special attention should be given to the segregation ofordinary trash and the routine collection of sponge, chips, andpowder from floor sweepings as a function of housekeeping.

A-9-1.13 For information on static electricity, see NFPA 77,Recommended Practice on Static Electricity .

A-9-2 Magnesium is a flammable solid that, once ignited, shallbe best extinguished by smothering (i.e., excluding oxygen).Burning magnesium responds poorly to several types of extin-guishing agents used for other types of materials. Use of inap-propriate agents can result in accelerating the fire or incausing an explosion (due to hydrogen).

A-9-2.2 Automatic sprinkler protection should not be used inareas of buildings where fine magnesium powders or dusts arepresent, such as blending operations areas. Automatic sprin-kler protection should not be used in areas where moltenmetal can be present.

A-9-3.1 The following agents should not be used as extinguish-ing agents on a magnesium fire because of adverse reaction:

(a) Water(b) Gaseous-based foams(c) Halon(d) Carbon dioxide(e) Sand and other high SiO2 –containing materials

A-9-3.2 Application of wet extinguishing agents accelerates amagnesium fire and could result in an explosion.

A-9-3.5 Water-based extinguishers approved for use on ClassA fires should be used only on fires involving ordinary combus-tibles. Extinguishers approved for Class B fires should be usedfor fires involving oil, grease, and most flammable liquids.Extinguishers approved for Class C fires should be used forfires involving electrical equipment.

A-9-3.6 Experience has shown that dry sodium chloride is oneof the most effective chemicals for containing zirconiumsponge or fines fires. Fire-fighting salts should be checkedperiodically to ensure that they have not become caked frommoisture. Another effective chemical is a nonmetallic fluxcompound consisting of potassium chloride, magnesium chlo-ride, and calcium fluoride. Commercial dry powder fire extin-guishers or agents approved for use on combustible metalsalso are effective. Covering the fire completely reduces theaccessible oxygen supply, thereby slowing the burning rate sothat eventual extinguishment is achieved.

A-9-3.8 Keeping the equipment in operation until all burningmaterial is removed can reduce damage to the equipment.Small amounts of burning materials can be handled with ashovel to facilitate removal.

Appendix B Supplementary Informationon Magnesium

This appendix is not a part of the requirements of this NFPA doc-ument but is included for informational purposes only.

B-1 Properties. Magnesium, a silvery white metal with anatomic weight of 24.32 and specific gravity of 1.74, is one of thelightest known structural metals. The melting point of magne-sium is 1202°F (650°C). The ignition temperature is generallyconsidered to be close to the melting point, but ignition ofmagnesium in certain forms can occur at temperatures belowthe melting point. Magnesium ribbon, fine magnesium shav-ings, and magnesium powders can be ignited under certainconditions at temperatures of about 950°F (510°C), and a veryfinely divided magnesium powder has been ignited at temper-atures below 900°F (482°C).

Commercially pure magnesium contains traces of alumi-num, copper, iron, manganese, nickel, and silicon, but thesecontaminants in typical analyses generally total less than 0.2percent. Metal marketed under different trade names andcommonly referred to as magnesium might be one of a largenumber of different alloys containing different percentages ofmagnesium, aluminum, zinc, and manganese. Some of thesealloys can have ignition temperatures considerably lower thanthat determined for pure magnesium. In some cases, the melt-ing point of certain alloys can be as low as 800°F (427°C) andcan ignite if held at this lower temperature for some time.

1998 Edition

APPENDIX B 480–17

B-2 Radioactive Alloys. A few magnesium alloys are pro-duced that contain thorium. Thorium, which is a low-levelradioactive material, is used in these alloys up to a nominalconcentration of 3 percent.

The natural decay or “daughter” products of thorium arelocked in the alloy until such time as the metal is melted,burned, or chemically disintegrated. Under fire conditions,these decay products exist within visible fumes and are dilutedas the visible fumes dissipate. These elements can be inhaledwith possible irradiation of lung tissue and deposition in bonestructure. Maximum permissible airborne concentrations ofsuch radioactive materials have been established by theNuclear Regulatory Commission and are based on continuousexposure for a normal 40-hour work week.

B-3 Spot Tests for Magnesium.

B-3.1 Acetic Acid Test. In the construction or assembly ofcertain machinery or equipment, magnesium or one of itsalloys having similar properties might be used for a few of thecomponent parts, and where finished or painted products arebeing stored or handled, it can be difficult to determine thepercentage of magnesium. Investigation has shown that silvernitrate or acetic acid (vinegar) can be used to distinguishbetween parts composed of magnesium and those composedof aluminum. The portion of metal to be tested is first cleanedof grease, dirt, oxide, et cetera, using sandpaper or steel wool.After the test area has been prepared, a drop of acetic acid isplaced on it. If hydrogen bubbles develop, then the piecebeing tested is magnesium.

B-3.2 Silver Nitrate Test. The test solution is prepared by dis-solving about 5 g of silver nitrate (AgNO3) in 1 L of distilledwater. The application of this solution immediately producesa black coloration on magnesium or a magnesium alloy. (Thiscoloration is essentially reduced silver.) No coloration is notedon aluminum and its alloys, or most other metals. Zinc andcadmium exhibit a similar black coloration but are muchheavier.

B-4 Combustibility and Explosibility. The ignitibility poten-tial of magnesium depends to a large extent upon the size andshape of the material as well as the size and intensity of thesource of ignition. Where magnesium exists in the form of rib-bon, shavings, or chips with thin, featherlike edges, or asgrinding dust, a spark can be sufficient to start the materialburning. Heavier pieces such as ingots and thick wall castingsare difficult to ignite because heat is conducted away rapidlyfrom the source of ignition. If the entire piece of metal israised to the ignition temperature [about 1200°F (649°C) forpure magnesium and many of the alloys], self-sustained burn-ing will occur.

The combustibility of magnesium, the ineffectiveness ofordinary types of extinguishing agents on magnesium fires,and the fact that, under certain conditions, the application ofsome of these agents intensifies burning and can releasehydrogen to form an explosive gas–air mixture, all combine tocreate serious fire and explosion hazards.

Magnesium, in its solid form, melts as it burns and can formpuddles of molten magnesium that, in the presence of suffi-cient moisture, can pose explosion hazards similar to thoseassociated with other molten metals.

B-5 General.

B-5.1 Electrically conductive flooring is often employed inmagnesium powder plants, although it is recognized that it is

difficult to maintain the conductivity of the floor over a periodof time using currently available materials.

B-5.2 The surface of a conductive floor provides a path ofmoderate electrical conductivity between all persons and por-table equipment making contact with the floor, thus prevent-ing the accumulation of dangerous static electric charges.

B-5.3 The maximum resistance of a conductive floor is usuallyless than 1,000,000 ohms, as measured between two electrodesplaced 3 ft (0.3 m) apart at any two points on the floor. The min-imum resistance is usually greater than 25,000 ohms, as mea-sured between a ground connection and an electrode placed atany location on the floor. This minimum resistance value pro-vides protection for personnel against static electric shocks.Resistance values should be checked at regular intervals.

B-6 Testing for Minimum and Maximum Resistance. Thefollowing equipment and procedures are accepted practice.

B-6.1 Each electrode weighs 5 lb (2.2 kg) and has a dry, flat,circular contact area 2.5 in. (63.5 mm) in diameter. The elec-trode consists of a surface of aluminum foil 0.0005 in. to 0.001in. (0.013 mm to 0.025 mm) thick, backed by a layer of rubber0.25 in. (6.4 mm) thick, and measuring 40 to 60 durometerhardness, as determined by a shore-type durometer or equiva-lent. (See ASTM D 2240, Standard Test Method for Rubber Property— Durometer Hardness.)

B-6.2 Resistance should be measured with a suitably cali-brated ohmmeter that can operate on a nominal open circuitoutput voltage of 500 volts dc and a short-circuit current of 2.5milliamperes to 10 milliamperes.

B-6.3 Measurements should be made at five or more locationsin each room and the results averaged.

B-6.4 To comply with the maximum resistance limit, the aver-age of all measurements should be less than 1,000,000 ohms.

B-6.5 To comply with the minimum resistance limit, no indi-vidual measurement should be less than 10,000 ohms, and theaverage of not fewer than five measurements should begreater than 25,000 ohms.

B-6.6 Where resistance to ground is measured, two measure-ments are customarily made at each location; the test leads areinterchanged at the instruments between the two measure-ments. The average of the two measurements is taken as theresistance to ground at that location. Measurements are cus-tomarily taken with the electrode or electrodes more than 3 ft(0.9 m) from any ground connection or grounded object rest-ing on the floor.

(If resistance changes appreciably over time during a mea-surement, the value observed after the voltage has beenapplied for about 5 minutes should be considered the mea-sured value.)

B-7 Building Construction. While noncombustible construc-tion is preferred for buildings occupied by magnesium melt-ing and processing operations, limited-combustible andcombustible construction can be permitted in appropriate cir-cumstances.

B-7.1 Moisture and foreign material are dangerous wheremolten metal is present. Such moisture can result from out-door storage or from collection of condensate during indoorstorage.

1998 Edition

480–18 STORAGE, HANDLING, AND PROCESSING OF MAGNESIUM SOLIDS AND POWDERS

B-7.2 Flash fires in fine dust can result in serious injury. Whilethe chance of a flash fire igniting castings is remote, a fire inaccumulated dust can be intense enough to cause ignition ofcastings.

B-7.3 Fire can occur in furnaces or ovens where magnesium isbeing heat-treated if there is lack of proper temperature con-trol or if the surface of the metal is not free of dust or fine par-ticles of metal. Failure to provide for proper circulation of theheated air in the furnace can result in overheating or highertemperatures in certain zones than those indicated by thethermocouples that operate the temperature control devices.

B-7.3.1 Direct contact between aluminum and magnesium atheat-treating temperatures promotes diffusion and alloying ofone metal with the other, resulting in the formation of low-melting, ignitible alloys.

B-7.3.2 Certain commonly used mixtures of molten nitratesand nitrites can react explosively with the magnesium alloysimmersed in them.

B-8 Machining magnesium includes sawing, turning, chip-ping, drilling, routing, reaming, tapping, milling, and shap-ing. Magnesium can usually be machined at the maximumspeeds obtainable on modern machine tools. The low powerrequired allows heavy depths of cut and high rates of feed,which are consistent with good workmanship. The resultingchips are thick and massive; they seldom ignite due to theirlarge heat capacity.

B-9 Magnesium pigs, ingots, and billets are not easily ignited,but they burn if exposed to fire of sufficient intensity.

B-9.1 Heavy castings [25 lb (11.3 kg) or greater] having wallswith large cross sections [at least 1/4 in. (6.4 mm)] can beignited after some delay when in contact with burning magne-sium chips or when exposed to fires in ordinary combustiblematerials.

B-10 Prime (commercially pure) magnesium chips and finesare commonly used in Grignard and other chemical reactions.These chips are generally free of contaminants and are notsubject to spontaneous ignition. Where such chips are pro-duced, shipped, and stored for chemical and metallurgicalprocess purposes, the conditions of handling and storage aresuch that a fire is unlikely.

Although water should not be applied to a large chip fire,automatic sprinklers are valuable in confining or extinguish-ing an incipient fire in packaging and in small amounts ofchips, provided detection and discharge are rapid.

B-11 Although the flame temperature of burning magnesiumis about 7200°F (3983°C), the heat of combustion is onlyabout half that of common petroleum products. Thus, fire-fighting personnel can move close to a fire during extinguish-ment, if care is exercised.

B-11.1 Fires in magnesium should be extinguished using aClass D extinguishing agent or a dry, inert granular material.

B-11.2 Magnesium fires are more easily extinguished ifattacked with the proper extinguishing agents during the earlystages of the fire. Certain extinguishing agents accelerate amagnesium fire. These agents include foam, carbon dioxide,halogenated agents, and dry chemical agents containing mono-or diammonium phosphate. Also, the use of water on a magne-sium chip or powder fire should be avoided. It is very difficult toextinguish a massive fire in magnesium powder. The majorproblem involves control of fires in the incipient stage.

The fire area should not be re-entered until all combus-tion has stopped and the material has cooled to ambienttemperature.

B-11.3 Reignition can occur due to high localized heat orspontaneous heating. To avoid reignition, the residual mate-rial should be immediately smothered.

B-11.4 It is recommended that a practice fire drill be con-ducted once each year to familiarize local fire department per-sonnel with the proper method of fighting Class D fires.

B-12 Provisions should be made to automatically cut off elec-trical power and lighting circuits in manufacturing buildingswhen one or more safety-sensing devices are activated by highpressure, low airflow, abnormal oxygen content, excessive vi-bration, or other pertinent factors that are being monitored.Alternatively, these sensing devices should be arranged tosound an alarm in those locations where prompt corrective ac-tion can be taken.

B-13 Temperature-sensing elements connected to alarms ormachine stop switches should be employed for locationswhere overheating of bearings or other elements might beanticipated.

B-14 Open bin storage is not desirable. Storage bins for pow-ders should be sealed and purged with inert gas prior to filling.

Appendix C Explosibility of Magnesium Dust

This appendix is not a part of the requirements of this NFPA doc-ument but is included for informational purposes only.

C-1 Definition. Deflagration. An explosion in which the rate of propaga-

tion of the flame front into the unreacted medium occurs atless than sonic speed. If the shock wave propagates at a rategreater than the speed of sound, it becomes a detonation.

C-2 Explosions in Magnesium–Air Dust Mixtures. Magne-sium dust is a potentially hazardous material when suspendedin air. The finer the dust particle size, the more easily it dis-perses, the longer it takes to settle, and the easier it is to ignite.

In order for a magnesium–air dust cloud to experience adeflagration (explosion), the following two conditions arenecessary:

(a) An ignitable concentration of dust in air(b) An ignition source of sufficient strength to ignite the com-

bustible air–dust mixture

Research conducted by the U.S. Bureau of Mines and oth-ers over many years has established values for these parame-ters. In using these data for the design of industrial equipmentand systems, it should be kept in mind that other factors suchas metal purity, particle size distribution, moisture, ambientpressure and temperature, and turbulence all affect the exactconditions for initiating explosions in such dust clouds.

A summary of the best available information for unalloyedmagnesium dust in air is listed in Table C-2. Attention isdirected to the fact that the data shown are for 200 mesh (lessthan 74 microns) in small unvented containers. These condi-tions are not truly representative of magnesium powder man-ufacturing but provide useful guidelines for avoidingaccidents. For this reason, an additional safety factor shouldbe used where applying this information to industrial-scaleoperations. A safety factor of 2-3 is suggested.

1998 Edition

APPENDIX C 480–19

Magnesium dust explosions are characterized by very rapidrates of pressure rise to a maximum pressure of approximately115 psig (793 kPa gauge). Limited industrial loss experienceindicates the use of venting and explosion suppression tech-niques can be impractical for large-size vessels. As a conse-quence, the avoidance of conditions that can lead to explosionsis of particular importance with fine magnesium powders.

It has been determined that the presence of some coarseparticles, greater than 100 mesh (150 microns) in size, in mag-nesium dust has little effect on the initiation of explosions insuch dust clouds. For this reason, the particle size distributionof the powders in air systems should be known, and equip-ment designs and safe operating procedures should be basedon the expected concentration of less than 100 mesh (lessthan 149 microns) powder in these systems. In the absence ofthis information, the total amount of powder should be used.While this can limit production rates, it provides an additionalfactor of safety when dealing with undocumented powders.

From a practical standpoint, a combination of explosioncontainment with other techniques might be the only other way

to avoid personal injury and property damage in manufactur-ing operations unless oxygen reduction by dilution with argonor helium is employed. This containment technique, togetherwith the avoidance of conditions that can lead to dust explo-sions, represents the best way of avoiding catastrophic accidentsin magnesium dust–handling equipment and systems.

Dust clouds can be ignited by flames, arcs, high-tempera-ture surfaces, and static and friction sparks, et cetera. Thedestructive effect of magnesium dust explosions can begreater than that of some vapor and gas explosions because ofthe comparatively high rate at which the pressure rises in somedust explosions. This results in longer impulse-loading on per-sonnel and structures than that resulting from a gas explosionand is the factor that causes a dust explosion to be moredestructive. Attention is directed to the fact that a 0.5 psig (3.5kPa gauge) overpressure will cause an 8-in. (200-mm) con-crete block wall to fail. It is obvious that this overpressure isreached extremely rapidly where the rate of pressure rise is15,000 psi/sec (103,410 kPa/sec) and the maximum pressurereached is 115 psig (793 kPa gauge).

In pneumatic conveying systems, proper selection of fan orblower capacity can be used to maintain a powder concentra-tion below the lower flammability limit (LFL) of 0.03 oz/ft3(0.03 g/L) shown in Table C-2. If the quantity of powder tobe transported is predetermined, the fan can be selected toprovide enough conveying air to keep the dust concentrationbelow the ignitible level. Care should be taken, however, tomaintain sufficient superficial air velocity [over 3500 ft/min(1068 m/min)] in the duct system to avoid saltation in hori-zontal lines and drop-out in vertical lines.

While the complete design of a “safe” system is beyond thescope of this appendix, a simplified example serves to illus-trate the above point. For instance, to transport 10 lb/min(4.5 kg/min) of fine [less than 100 mesh (less than 149microns)] magnesium powder introduced uniformly into anair-conveying system while maintaining a dust concentrationbelow the 0.03 oz/ft3(0.03 g/L) flammability level, the airflowis calculated as follows:

For a 14-in. (356-mm) diameter round duct, the superficialair velocity from the following equation is 4994 ft/min (1524m/min), neglecting density effects.

where:Q = quantity of airflowA = cross-sectional areaV = velocityQ = 5333.3/1.068 = 4994 ft/min (1524 m/mi)

NOTE: These calculations do not take into account the effectsof temperature, altitude, and humidity on the airflow. The resultindicates that to maintain a nonignitible dust concentration, theamount of air needed per pound of powder is quite large. Thestandard density of dry air is taken at 0.075 lb/ft3.

Table C-2 Explosion Characteristics of Unalloyed Magnesium Dust in Air [200 Mesh (74 microns)]

Explosion Characteristics Values

Explosibility index1 10

Ignition sensitivity2 3.0

Explosion severity3 7.4Maximum explosion pressure 115 psig (793 kPa gauge)Maximum rate of pressure rise 15,000 psi/sec (793 kPa

gauge)Ignition temperature cloud 1040°F(560°C)Minimum cloud ignition energy

0.04 joules (26.4 watt/sec)

Minimum explosion concen-tration

0.03 oz/ft3

Limiting oxygen percent for spark ignition4 —

Note: KSt values vary for specific particle sizes.1Explosibility Index = ignition sensitivity × explosion severity2Ignition sensitivity =

3Explosion Severity =

4Burns in carbon dioxide, nitrogen, and halons.

[Ignition temp. min. energy× min. concentration (LEL)]×

Pittsburgh coal dust[Ignition temp. min. energy×

min. concentration]×sample dust

-------------------------------------------------------------------------------

[Max. explosion ×max. rate of pressure rise]

Pittsburgh Coal Dust[Max. explosion ×

max. rate of pressure rise]

sample dust

--------------------------------------------------------------------

Air needed 10lb/min 16 oz×

0.03 oz/ft3---------------------------------------------- 5333.3 ft3/min==

Q AV=

5333.3 ft3/min( )10 lb

-------------------------------------------- 0.075 40 lb=×

1998 Edition

480–20 STORAGE, HANDLING, AND PROCESSING OF MAGNESIUM SOLIDS AND POWDERS

Therefore, highly diluted phase-conveying is necessary forsafe operation. With the added recommended safety factor of2 to 3, this ratio becomes much greater. Observing these guide-lines provides a simple starting point for the design of a rea-sonably safe system for air-conveying fine magnesium powder.

In air-separating cyclones, the dust concentration can beassumed to approximate the concentration in the conveyinglines less an allowance of 10 percent for air-lock leakage, et cet-era. Nearly all of the conveying air entering a cyclone leavesthrough the vent, and there are no semistagnant air spacesexcept for the small volumes of the dust trap and dip-leg.

NOTE: Attention is directed to the difference between thissituation and a grain silo, where a large amount of dust is dis-charged by gravity from the separator into a semistagnant air ina large cylindrical tank or silo, which allows the dust concentra-tion to materially increase.

As a consequence, the concentration of magnesium fines[less than 100 mesh (less than 149 microns)] in the air in aproperly designed cyclone separator does not exceed the LFLin such units where the recommended safety factor and otherconsiderations referred to previously are used as guideline.

With regard to the presence of ignition sources of suffi-cient strength to ignite a dust cloud, if the LFL of 0.03 oz/ft3

(0.03 g/L) is exceeded, it should be noted that the 40 milli-joules energy required to ignite such a dust cloud is nearly 20to 50 times greater than that required to ignite flammable gasor vapor mixtures. Such strong ignition sources do not gener-ally exist in magnesium powder plants that operate with light-ning protection and electrically bonded and groundedequipment to minimize static electricity, and that have strongmagnetic separators to remove tramp metals from processstreams, where all the above safety equipment and arrange-ments are regularly inspected and maintained.

C-3 Chemical Process to Render Magnesium Fines Noncom-bustible. Metallic magnesium fines generated in the produc-tion of structural magnesium parts or other products oftenhave no commercial value and can present a fire hazard. Theyshould be disposed of regularly. These fines might be the wetfines from a dust collector system, partially converted to an in-active state by having been collected in water, or chips from amachining operation. Chips and turnings can be wet, dry, oroil-soaked, and, frequently, they are contaminated. Fines varyin size from the dust generated in a sanding or buffing opera-tion to a much larger particle produced by sawing, drilling, orturning. Prior to disposing of any fines, a secondary proces-sor/melter should be contacted to assess the recycled value ofthe by-product.

In seeking a means of disposal for magnesium fines, otherthan by burning, the most obvious solution is to immerse themin water. Magnesium fines can be rendered partially inactiveby reacting them with water to form hydrogen and noncom-bustible magnesium hydroxide. Film formation on the magne-sium, however, normally slows the process beyond practicallimits; however, once substantially reduced to magnesiumhydroxide, the residual sludge does not burn and can be dis-posed of like any other inert material. It has been found thatpartially inactivated magnesium fines containing approxi-mately 10 percent metallic magnesium do not burn.

Magnesium sludge can more effectively be rendered chem-ically inactive and noncombustible by reacting it with a 5 per-cent solution of ferrous chloride (FeCl2•2H2O). The reactiontakes place with the evolution of hydrogen at a rate such thatthe magnesium fines are changed in less than 24 hours to a

concentration of magnesium hydroxide so that the residuecannot burn. Since hydrogen is generated by the reaction, theprocess should be carried out in an open container placedoutside in a location where natural air movement will preventthe accumulation of explosive concentrations of hydrogen inair. Open flames and smoking should be prohibited in theimmediate vicinity of the process. The amount of FeCl2•2H2Ocommonly employed in the decomposition is approximately0.6 lb (0.3 kg) for each pound of magnesium fines (dryweight). The amount of water in the fines should be consid-ered in determining the weight of the magnesium fines. Exactconcentrations should be determined on the basis of the typeof fines being handled. The cycle can be repeated easily in thesame container until the amount of brown, damp residue issuch that the container should be cleaned out. To be certainof complete reaction, a sample of the residue should beheated with a Bunsen burner or oxyacetylene torch to deter-mine if it can be ignited. Although the method is simple, itshould be operated under strict technical supervision to avoiddisposal of partially reacted magnesium.

The main constituent of the residual sludge is magnesiumhydroxide [Mg (OH)2], which indicates that the iron salt func-tions not as a reagent that is consumed in the reaction, butrather as a catalyst that simply promotes the reaction withwater to form magnesium hydroxide and hydrogen gas. Con-siderable heat is generated in the early stages of the reaction,especially if the particles are finely divided and clean. Duringthis stage, considerable hydrogen is released and foaming canoccur. Small amounts of hydrogen continue to evolve until nometallic magnesium is present.

It should be remembered that this is a chemical reactionand the results obtained depend on several factors. It has beenmentioned that freshly formed, finely divided particles reactquite quickly, so that considerable heat, hydrogen evolution,and foaming can occur. In case of excessive foaming, the reac-tion should be slowed down, or a defoamer can be added. Ifthe fines have been under water in a collector system for sometime, less metallic magnesium is present, and the reaction isslower. Particles coated with oil or tar pose special problems,and the use of a detergent might be advisable. If the reactionis carried out in a container that has little surface area and lim-ited excess water, the heat of reaction might be sufficient toignite the hydrogen. Hydrogen is less liable to be trapped in ashallow container, and a larger surface area provides betterheat dissipation.

It is recommended that the details of the process beworked out by technically competent personnel. The dailyoperation can be performed on a routine basis under techni-cal supervision. If excessive heating is a problem, more watercan be added. It has been found that a weaker solution will fre-quently render the material noncombustible in the desiredlength of time with less initial heating. The reaction vessel canbe mild steel. In one case, a tank constructed of 1/4-in. (6.4-mm) thick mild steel, in almost constant use, lasted 10 yearsbefore leaking.

Ferric chloride (FeCl3) in dilute amounts can be used inplace of ferrous chloride (FeCl2) to produce the same results.The initial rate of reaction is faster when using ferric chloride;however, this can be controlled by adding more water or ini-tially adding the magnesium fines slowly. Solutions of FeCl3 inwater as low as 1 percent dilute have been used to render cer-tain types of magnesium fines noncombustible within 24hours.

1998 Edition

APPENDIX D 480–21

FeCl3 is available in crystalline form (FeCl3•6H2O) or theanhydrous form (98 percent FeCl3). Either can be used, butthe anhydrous form should be handled like an acid because ofthe hazard posed by chemical burns to the skin and eyes. Infiguring the required amounts of either FeCl2 or FeCl3, thewater produced by crystallization should be considered indetermining the strength of the solution.

Several companies have used either FeCl2 or FeCl3 to ren-der magnesium fines noncombustible. The general experi-ence supports the original work done on a laboratory scale.The following two examples provide information of interest.

Case 1Material Treated: Fines from wire-brushing sheet collected

in a wet dust collector or fine shavings from a milling opera-tion.

Tank Size: 8 ft (2.4 m) wide × 20 ft (6.1 m) long × 27 in.(686 mm) deep.

Amount of Fines Treated: Amount of fines in water solutionvaries considerably from batch to batch. Several hundredpounds have been treated at a time.

Amount of Chemical Added: 25 lb (11.4 kg) of FeCl2•6H2O or15 lb (6.8 kg) of anhydrous FeCl3 (98 percent FeCl3) per 100gal (379 L) of liquid in the tank. FeCl2•2H2O is added as apowder; FeCl3•6H2O is added in cake form; the 98 percentFeCl3 is a powder and is made up as a water solution andpumped into the tank.

Result: Little heat evolution, low foaming, and a noncom-bustible sludge within 24 hours.

NOTE: The reaction is carried on outside, and a steam coil isused to warm the solution in the winter. The residue is checkedwith a propane torch to determine combustibility. Adequateprotection from chemical burns is provided where using anhy-drous FeCl3 (98 percent).

Case 2Material Treated: Fines generated by sanding of magnesium

die castings that have been collected in a wet dust collector.Tank Size: 5 ft (1.5 m) wide × 8 ft (2.4 m) long × 31/2 ft

(1 m) deep (steel dumpster box).Amount of Fines Treated: Approximately 60 lb (27 kg) mag-

nesium fines in a 55-gal (208-L) drum filled with fines andwater. To this is added approximately 92 gal (348 L) of waterthat results in a liquid depth of 5 in. (127 mm) in the tank.

Amount of Chemical Used: 44 lb (20 kg) of 98 percent FeCl3added with an aluminum hand scoop.

Result: Some heat evolution, foaming, and a noncombusti-ble sludge within 24 hours.

NOTE: If too much ferric chloride is used at once, the reac-tion is quite violent. Where 100 lb (45.4 kg) of magnesiumfines were treated, the foam overflowed the tank. Each lot istested for combustibility with a propane torch. The operator isprotected against chemical burns while adding the FeCl3 to thesolution.

The following generalizations taken from the experienceof users provides further information of interest.

(a) The magnesium fines can be added to the solution orthe solution added to the fines. Additional fines can be addedto a previous batch containing inactivated sludge. Experienceindicates the time needed to complete each reaction and theamount of either FeCl2 or FeCl3 that needs to be added witheach increment of fines.

(b) The ratio of FeCl2 or FeCl3 to magnesium content issubject to alteration based on a number of conditions, but the

reaction takes place over a broad range of concentrations. Theamount required should be determined for the fines beingtreated and the time allowed for reaction. The recommenda-tion is to use 0.6 lb (0.3 kg) of FeCl2•2H2O for each pound ofmagnesium fines (dry weight). The upper limit on concentra-tion used has been 5 percent, but in many cases a lower con-centration has been satisfactory and has produced less initialheat and foaming.

(c) Personnel handling anhydrous FeCI3 or FeCI3 solu-tions should wear overalls, rubber aprons, rubber gloves, andchemical goggles.

(d) Moist fines should not be flushed through long linesbecause they can build up a layer of semimoist material in thepipe. Inert sludge does not create a fire hazard under thesesame conditions.

(e) Heating with a steam line has been used to speed upthe reaction process, especially in winter and after the initialrapid reaction stage is over.

(f) Foaming can be decreased by the use of defoamingagents. A greater quantity of water limits the heating and slowsdown the formation of foam.

(g) Longer reaction times might be needed to inactivatelarger particles or those that are covered with oil or tars.

(h) For the purpose of estimating metal content, a ft3 (m3)of material taken from a wet dust collector should be assumedto contain approximately 30 lb (13.6 kg) of metallic dust and6 gal (23 L) of water. Approximate weights used for dry finesare 50 lb/ft3 (800 kg/m3) of sawdust and 15 lb/ ft3 (240 kg/m3) of rotary filings.

(i) Particular care should be taken in adding the initial1/4 lb to 1/2 lb (0.11 kg to 0.22 kg) of magnesium fines perpound of FeCl2 or FeCl3 content of the solution. During thisperiod, the reaction rate can be very rapid with fine powders(60 to 80 percent completion in 5 minutes), due to the initialacidity of the iron chloride salts. Beyond this point, however,the reaction rate moderates to a stable 4 to 5 percent of com-pletion every 5 minutes (50 to 60 percent per hour).

(j) If magnesium and aluminum fines are mixed, the mag-nesium still reacts with the FeC12 or FeC13.

(k) Partially deactivated fines containing 10 percent metal-lic magnesium do not support combustion.

(l) After reaction is complete, the inert residue should bedisposed of as waste or fill material.

Although this method has been widely used in the past, cur-rent environmental regulations should be met; therefore, areview with local authorities should be conducted to ensurecompliance with all local, state, and federal requirements.

Appendix D Referenced Publications

D-1 The following documents or portions thereof are refer-enced within this standard for informational purposes onlyand are thus not considered part of the requirements of thisstandard unless also listed in Chapter 10. The edition indicat-ed here for each reference is the current edition as of the dateof the NFPA issuance of this standard.

D-1.1 NFPA Publications. National Fire Protection Associa-tion, 1 Batterymarch Park, P.O. Box 9101, Quincy, MA 02269-9101.

NFPA 13, Standard for the Installation of Sprinkler Systems,1996 edition.

1998 Edition

480–22 STORAGE, HANDLING, AND PROCESSING OF MAGNESIUM SOLIDS AND POWDERS

NFPA 51B, Standard for Fire Prevention in Use of Cutting andWelding Processes, 1994 edition.

NFPA 68, Guide for Venting of Deflagrations, 1998 edition.NFPA 77, Recommended Practice on Static Electricity , 1993 edi-

tion.NFPA 221, Standard for Fire Walls and Fire Barrier Walls, 1997

edition.NFPA 499, Recommended Practice for the Classification of Com-

bustible Dusts and of Hazardous (Classified) Locations for ElectricalInstallations in Chemical Process Areas, 1997 edition.

NFPA 651, Standard for the Machining and Finishing of Alumi-num and the Production and Handling of Aluminum Powders, 1998edition.

NFPA 704, Standard System for the Identification of the Hazardsof Materials for Emergency Response, 1996 edition.

D-1.2 Other Publications.

D-1.2.1 ASTM Publication. American Society for Testing andMaterials, 100 Barr Harbor Drive, West Conshohocken, PA19428-2959.

ASTM D 2240, Standard Test Method for Rubber Property —Durometer Hardness, 1991 edition.

D-1.2.2 AMCA Publication. Air Movement and Control Asso-ciation, 30 W. University Drive, Arlington Heights, IL 60004-1893.

AMCA Standard No. 99-0401, 1991.

D-1.2.3 U.S. Bureau of Mines Publication. U.S. Bureau ofMines, Cochrans Mill Road, Pittsburgh, PA 15236-0070.

RI 6516, “Explosibility of Metal Powders,” M. Jacobson, A.R. Cooper, and J. Nagy, 1964.

D-1.2.4 U.S. Government Publication. Superintendent ofDocuments, U.S. Government Printing Office, Washington,DC 20402.

Title 49, Code of Federal Regulations, Parts 100-199.

D-2 Additional Publications. This part of the appendix listsother publications that are pertinent to the subject of thisNFPA document and that might or might not be referenced.

Bartknecht, W., “Explosions Pressure Relief,” ChemicalEngineering Progress, 11th Loss Prevention Symposium,Houston, 1977.

Bartknecht, W., Exploseonen, 1979 Springer-Verlog Berlin,Heildeberg, NY.

Bartknecht, W., “Report on Investigations on the Problemof Pressure Relief of Explosions of Combustible Dusts in Ves-sels,” Staub Reinhalt, Luft, Vol. 34, No. 11, Nov. 1974, and Vol.34, No. 12, Dec. 1974.

Bodurtha, F. T., Industrial Explosion, Prevention and Protec-tion, McGraw Hill, New York, 1980.

“Combustible Dusts,” Loss Prevention Data Sheet 7-76,1976, Factory Mutual Research Corp., Norwood, MA.

Donat, C., “Pressure Relief as Used in Explosion Protec-tion,” Chemical Engineering Progress, 11th Loss PreventionSymposium, Houston, 1977.

Fire Protection Handbook, 18th ed., National Fire ProtectionAssociation, Quincy, MA, 1991.

“Industrial Ventilation: A Manual of Recommended Prac-tice,” 23rd ed., Lansing, MI, American Conference of Govern-mental Industrial Hygienists, 1997. Available from KemperWords Center, 1330 Kemper Meadow Drive, Cincinnati, OH45240.

Palmer, K.N., Dust Explosions and Fires, Chapman & Hall,London, 1973.

Index

1998 National Fire Protection Association. All Rights Reserved.

The copyright in this index is separate and distinct from the copyright in the document which it indexes. The licensing provisions set forth for thedocument are not applicable to this index. This index may not be reproduced in whole or in part by any means without the express written per-mission of the National Fire Protection Association, Inc.

-A-

Access, fire fighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1.1Air, compressed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1.5, 7-1.1Aluminum . . . . . . . . . .3-2.6, 3-2.9, A-3-2.6, A-3-2.9, A-4-2.4.1, A-4-2.4.8Approved (definition) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4, A-1-4Authority having jurisdiction (definition) . . . . . . . . . . . . . . . . 1-4, A-1-4

-B-

Bearings, grounded/bonded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2.3Billets

Ignition of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-9Storage of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-1, A-8-1

Bonded bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-2.3, A-5-2.3Bonding

Containers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4.2Ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-3.4, A-6-3.4Dust collectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-5.4, A-6-5.4Magnesium powder machinery . . . . . . . . . . . . 5-2.2 to 5-2.3, A-5-2.2Processing equipment . . . . . . . . . . . . . . . . . . . . . . . . 9-1.13, A-9-1.13Vacuum cleaners. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1.2.2, A-7-1.2.2

Building construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3, B-7

-C-

Casting operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1, A-3-1Castings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see also Heavy castings

Light castings, storage of. . . . . . . . . . . . . . . . . . . . . . . . . .8-3, A-8-3.4Cleaning . . . . . . . . . . . . . . . . . . . . . . . Chap. 7, 9-1.4, 9-1.6, A-7, A-9-1.6

Compressed air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-1.1Ductwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6.3Dust collecting system . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6.2 to 4-6.3Electrical equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4.2Frequency of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3.1, 7-2, A-7-2.1Grinding area. . . . . . . . . . . . . . . . . . . . . 4-3.1, 4-6.2 to 4-6.3, A-4-6.3Hotwork, prior to . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1.2, A-9-1.2

Clothing, protective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1.7, 4-6.1Combustibility of magnesium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-4Compressed air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1.5, 7-1.1Concrete, contact with hot materials of . . . . . . . . . . . . . . . . . . . A-3-1.4Conductive flooring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-5.1 to B-5.3Containers

For cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3.2Magnesium powder . . . . .5-4.1 to 5-4.2, 5-5, 6-1, 8-6.4, 8-6.8, A-8-6.4Magnesium scrap . . . . . 8-5.3 to 8-5.6, 9-1.8, A-8-5.4, A-8-5.6, A-9-1.8Molten magnesium . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1.3, A-9-1.3Removal in case of emergency . . . . . . . . . . . . . . . . . . . . . . . . . 9-1.14

1998 Edition

INDEX 480–23

Conveying systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chap. 6, A-6Containers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1Ductwork . . . . . . . . . . . . . . . . . . . . . . . . .6-3, A-6-3.1, A-6-3.2, A-6-3.4Dust collectors. . . . . . . . . . . . . . . . . . . . . . . . 5-1.1, 5-2.1, 6-5, A-6-5.4Fan construction and arrangement. . . . . . . . . . . . . . . . . 6-4, A-6-4.1Grounding. . . . . . . . . . . . . . . . . . . . 5-2.2 to 5-2.3, A-5-2.2 to A-5-2.3Pneumatic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2, A-6-2.2, A-6-2.5Sparks, control of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1.1

Cutting . . . . . . . . . . . . . . . . . . . . . . . .4-1.1, 4-6.3, 9-1.2, A-4-6.3, A-9-1.2Cyclone dust collectors . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2.5, A-4-2.5.5

-D-

Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4, A-1-4, C-1Deflagration

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see Explosion vents

DoorsExits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4.1Fire. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4.2

Down-draft wet collectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2.4.7Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-7Drills, fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-11-4Dry-type dust collectors . . . . . . . . 4-2.5, 6-5.1, 6-5.5 to 6-5.6, A-4-2.5.5Ductwork . . . . . . . . . . . . . . . . . . . . . . . . .4-6.3, 6-3, 6-5.3, A-4-6.4, A-6-3Dust accumulations

Hotwork and . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6.3, A-4-6.3Pneumatic conveying systems . . . . . . . . . . . . . . . . . . . .6-2.5, A-6-2.5Prevention of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6.6, Chap. 7, A-7

Dust collection . . . . . . . . . . 4-2, 4-6.6; see also Dry-type dust collectors;Wet-type dust collectors

Cleaning of system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6.2 to 4-6.3Conveying systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5, A-6-5.4Ductwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2.5.4, 4-2.6Vacuum cleaners . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3.3, 7-1.2, A-4-3.3

-E-

Electrical classification . . . . 2-6.2, 4-4.1, 8-6.6, A-2-6.2, A-4-4.1, A-8-6.6Electrical equipment . . . . . . . . . . . . . . . . . . . . . . . . . 4-4, 9-1.11, A-4-4.1Electrical power

Automatic cutoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-12 to B-13Powder production plants . . . . . . . . . . . . . . . . . . . . . . . . 2-6, A-2-6.2

Emergency lighting systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6.3Enclosures, dust collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2.1Equivalent protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3Exits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2.1, 2-4.1Explosion prevention systems . . . . . . . . . . . . . . . . . . . . . . . . . . A-6-3.2Explosion vents . . . . . . . . . . 4-2.5.5, 6-3.1 to 6-3.2, 6-5.5, 8-5.5, A-2-4.3,

A-4-2.5.5, A-6-3.1, A-6-5.5, A-7-1.2, A-8-5.5Explosions . . . . . . . . . . . . . . . . . . .A-3-1.2, A-3-1.4, A-9-1.3, B-4, App. C

Magnesium–air dust mixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2Unalloyed magnesium dust, characteristics of . . . . . . . . . Table C-1

Extinguishers, portable fire . . . . . . . . . . . . . . . . . 9-3.4 to 9-3.5, A-9-3.5Extinguishing agents . . . . . . . . .8-5.9, 8-6.7, 9-3, A-9-3, B-11.1 to B-11.2

-F-

Fans, conveying system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4, A-6-4.1Fences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2.2Fire doors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4.2Fire prevention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1

Chemical process to render magnesium fines

noncombustible . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C-3Electrical power cutoff . . . . . . . . . . . . . . . . . . . . . . . . . .B-12 to B-13

Fire protection . . . . . . . . . . . . . . 9-2 to 9-3, A-9-2 to A-9-3, B-11; see alsoExtinguishing agents; Sprinkler systems

Fire drills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-11.4Machining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1.6Processing equipment, continued operation of . . . . . 9-3.8, A-9-3.8Reignition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-11.3

Fire-fighting organizations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-2.5Fire-resistive (definition) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4Flash fires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-4-1, B-7.2Flashlights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4.3Floors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-3.3, 3-1.1

Conductive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-5.1 to B-5.3Storage areas . . . . . . . . . . . . . . . . . . . . . . . . . . .8-1.3.2, 8-2.2, A-8-2.2

Foreign materials, molten magnesium contact with . . . . . . . . . . . 3-1.4Foundry operations . . . . . . . . . . . . . see Mill and foundry operationsFrictional heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1.4, A-5-1.4Fuel supply, safety controls for . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1.3Furnaces

Heat treating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2, A-3-2, B-7.3Melting and casting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1, A-3-1

-G-

Gases, used for conveying systems . . . . . . . . . . . 6-2.1 to 6-2.4, A-6-2.2Grounding

Building steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5, A-2-5Containers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-4.2, 6-1.3Ducts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-3.4, A-6-3.4Dust collection systems . . . . . . . . . . . . . . . . . . . . . . . . .6-5.4, A-6-5.4Machining and fabrication equipment . . . . . 2-5, 4-5, 9-1.13, A-4-5,

A-9-1.13Magnesium powder machines . . . . 2-5, 5-2.2 to 5-2.3, 9-1.13, A-2-5,

A-5-2.2 to A-5-2.3, A-9-1.13Trucks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1.3Vacuum cleaners . . . . . . . . . . . . . . . . . . . . . . . . . . .7-1.2.2, A-7-1.2.2

-H-

Heat treating. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2, A-3-2Heavy castings

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4Ignition of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-9.1Storage of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-2, A-8-2.2, A-8-2.6

High-helix drills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1.2, A-4-1.2Hoods, dust collection . . . . . . . . . . . . . . . . . . . . . . . 4-2.1, 4-6.4, A-4-6.4Hotwork permits . . . . . . . . . . . . . . . . . . . . . . . . . 9-1.2, A-4-6.3, A-9-1.2Housekeeping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see CleaningHydrogen gas generation . . . . . . . .4-1.4, 4-2.4.3 to 4-2.4.4, 4-6.3, 5-1.2,

A-4-2.4.1, A-4-2.4.8, A-8-6.4

-I-

Indoor storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-1.3, A-8-1.3Industrial trucks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1.2Inert gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2.2 to 6-2.3, A-6-2.2Ingots

Ignition of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-9Storage of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-1, A-8-1

Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4.2, 9-1.7Iron scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2.10, A-3-1.4, A-3-2.10

1998 Edition

480–24 STORAGE, HANDLING, AND PROCESSING OF MAGNESIUM SOLIDS AND POWDERS

-L-

Labeled (definition) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4Lanterns, battery-operated. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4.3Light castings, storage of . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3, A-8-3.4Listed (definition). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4, A-1-4Lubricants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1.4, 5-1.4

-M-

Machinery, magnesium powder . . . . . . . . . . . . . . . . . . . . . Chap. 5, A-5Machining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1, A-4-1, B-8Magnesium

Chips . . . . . . . . . . . 3-2.4, 4-1.2, 4-1.6, 8-2.3, 8-5, 9-1.2, 9-1.6 to 9-1.8,9-3.2, A-3-1, A-4-1, A-9-3.2, B-10

Combustibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-4, B-11Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4Dust

Accumulations . . . . . . . . . . . . . . . . . . . . see Dust accumulationsCollection . . . . . . . . . . . . . . . . . . . . . . . . . . . . see Dust collectionMinimum explosible concentrations . . . . . . . . . . . . . . . A-4-2.4.2

Explosibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-4, App. CFines . . . 8-5.4, 9-3.7, A-4-1.2, A-4-2.4.1, A-4-2.4.8, A-8-6.4, B-10, C-3Molten . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1, 9-1.3, A-3-1, A-9-1.3Powder. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1.2

Charging and discharging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4Fire prevention. . . . . . . . . . . . . . . . . . . . . . . . . 9-1.2, 9-1.6 to 9-1.8Fire-fighting procedures . . . . . . . . . . . . . . . . . . . . . . 9-3.2, A-9-3.2Ignition of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3-1Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-5Storage of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5, 8-6

Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-1, C-2Radioactive alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-5, A-8-5.4 to A-8-5.5Solids

Ignition of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-9-2Storage of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chap. 8. A-8

Swarf . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see SwarfTransportation of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1.4, A-1-1.4

Magnesium powder production plantsBuilding construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3, B-7Conductive flooring . . . . . . . . . . . . . . . . . . . . . . . . . . . B-5.1 to B-5.3Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4Doors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4.1 to 2-4.2Electrical power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6, A-2-6.2Grounding of equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5, A-2-5Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1Machinery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chap. 5, A-5Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4.3, A-2-4.3

Melting operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1, A-3-1Mill and foundry operations

Heat treating. . . . . . . . . . . . . . . . . . . . . . . . . 3-2, A-3-2, Chap. 3, A-3Melting and casting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1, A-3-1

Moisture, contact with magnesium of . . . . . . . . 3-1.2, A-3-1.2, A-9-1.3;see also Water

Molten salt baths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2.8, A-3-2.8

-N-

Noncombustible (definition) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

-O-

Open flames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6.3, A-4-6.3

-P-

PigsIgnition of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-9

Storage of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1, A-8-1Pneumatic conveying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2Preheating of metal and tools . . . . . . . . . . . . . . . . . . . . . . 3-1.2, A-3-1.2Protective clothing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1.7, 4-6.1Purpose of standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

-R-

Radioactive alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2Referenced publications . . . . . . . . . . . . . . . . . . . . . . Chap. 10, App. DResistance, tests for minimum and maximum . . . . . . . . . . . . . . . . . B-6Roofs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3.4 to 2-3.5

-S-

Safety precautions, machining and fabrication operations . . . . . . . 4-6,A-4-6.3, A-4-6.4

Scope of standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1Security, site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2“Setting” of furnace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3-1.4Shall (definition) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4Should (definition) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4Smoking prohibition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-1.10Spark-producing operations . . . . . . . . . . . . 4-6.3, 5-1.1, 9-1.12, A-4-6.3Spinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7Sprinkler systems . . . . . . . . . . . . . . . . . . . . . . . . . 9-2.2 to 9-2.3, A-9-2.2

Chip fires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-10Indoor storage areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1.3.4Storage areas . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2.2 to 9-2.3, A-9-2.2

Finished products . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7.4, A-8-7.4Heavy castings, storage of . . . . . . . . . . . . . . . . . . . . . 8-2.6, A-8-2.6Light castings, storage of . . . . . . . . . . . . . . . . . . . . . 8-3.4, A-8-3.4Powder storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-6.2Rack or bin storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-4.2Scrap magnesium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-5.8

Stamping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7Standard (definition) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4Start-up operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3Static electricity . . . . . . . . . . . 5-1.1, 9-1.12, A-7-1.2.4; see also Bonding;

GroundingStorage

Combustible materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-1.5Finished products . . . . . . . . . . . . . . . . . . . . . . . . 8-7, A-8-7.1, A-8-7.4Heavy castings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2, A-8-2Light castings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-3, A-8-3.4Magnesium fines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-3.7Pigs, ingots, and billets . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1, A-8-1

Indoor storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1.3, A-8-1.3Yard storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-1.2

Powder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-5, 8-6Rack or bin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-4, B-14Scrap magnesium . . . . . . . . . . . . . . . . . . . . . . 8-5, A-8-5.4 to A-8-5.5

Swarf . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2.4, 8-5, A-3-1Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

-T-

TestsResistance, minimum and maximum. . . . . . . . . . . . . . . . . . . . . . B-6Silver nitrate test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-3.1Spot tests for magnesium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-3

Thermite reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3-1.4, A-3-2.10Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-1.12

Cutting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1.1, A-4-6.3Grooving and parting . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1.3 to 4-1.4High-helix drills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1.2, A-4-1.2Nonsparking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3.2, 4-6.5, 7-1.1Preheating of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1.2, A-3-1.2

Transportation of magnesium . . . . . . . . . . . . . . . . . . . . . . 1-1.4, A-1-1.4

1998 Edition

INDEX 480–25

-V-

Vacuum cleaners . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3.3, 7-1.2, A-4-3.3Vents, explosion . . . . . . . . . . . . . . . . . . . . . . . . . . see Explosion vents

-W-

Walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3.2Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see also Sprinkler systems

Accumulation/flow during fire . . . . . . . . . . . .A-3-1, A-8-1.3, A-8-2.2In concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3-1.4Contact with magnesium of . . . . . . . . . . . . . . . . . . . . . . 3-1.2, A-3-1.2Fines, contact with . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-8-6.4

Leakage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1.2, 8-6.5As lubricant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1.4Molten magnesium and . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-9-1.3

Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6.3, 9-1.2, A-4-6.3, A-9-1.2Wet-type dust collectors . . . . . . . . . 4-2.4, 4-2.6.1, A-4-2.4.1 to A-4-2.4.2,

A-4-2.4.8Down-draft collectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2.4.7

Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4.3, A-2-4.3Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-6.1, 9-1.11

-Y-

Yard storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-1.2

C-E 1998 Edition