Report of Commlttee on Dry Chemcal Extlngulshlng Systems

James Robert Ryan Chalrman Kemper Group

(Rep A11}ance of Amer}can Insurers)

John H Lawlor Secretary Keystone Fire Protect}on Co

(Rep NAFED)

Francls X Bender Safety Englneerlng Consultants W1111am M Carey Underwriters Laboratorles Inc W}lllam E Gale Jr Bechtel Petroleum Inc

Rep Amer}can Petroleum Instltute John Goudreau Wormald F}re Systems Inc

Rep Fire Equipment Manufacturers Assn Waiter M Haessler Santa.Rosa CA Edward D Leedy Industrial Risk Insurers Robert C Merrltt Factory Mutual Research Corp Lorne Roberts Lev}tt-Safety Ltd

Rep F1re Equ}pment Manufacturers Inst of Canada Eric Roblnson Gr}nnell Fire Protect}on Systems Co Inc

Rep NFSA W11l}am Scofleld K}dde Bellev}lle

Rep Compressed Gas Assn Inc R J Wr}ght Underwr}ters Labs of Canada

Alternates

Robert CMpman Chemetron Fire Systems (Alternate to L Roberts)

C W Conaway Industrial Risk Insurers (Alternate to E D Leedy)

Mervyn Gould K}dde-Bellev}lle (Alternate to J Goudreau)

W A Haas Underwriters Laboratories Inc (Alternate to W M Carey)

George A Krabbe Charles R Teas & Co Inc (Alternate to J H Lawlor)

Lawrence K Marks Kemper Group (Alternate to J R Ryan)

Irwln G Patch Compressed Gas Assn Inc (Alternate to W Scofleld)

George Unger Underwrlters Labs of Canada (Alternate to R J Wrlght)

TMs l ls t represents the membersMp at the tlme the Commlttee was balloted on the text of thls edltlon Since that tlme changes in the membersMp may have occurred

The Committee on Dry Chemlcal ExtlngulsMng Systems proposes for adoption its Report on a complete revlslon to NFPA 17 1980 Standard for Dry Chemlcal ExtlngulsMng Systems NFPA 17-1980 is publlshed in Volume I of the 1984 Natlonal Fire Codes and in separate pamphlet form

TMs Report has been submltted to letter ballot of the Technlcal Commlttee on Dry Chemlcal Ext~ngu}shlng Systems wh}ch conslsts of 13 votlng members of whom 11 voted aff}rmatlvely 1 negatlvely (Mr Goudreau) and 1 ballot was not returned (Mr Haessler)

Mr Goudreau voted negatlvely because of the word}rig of Sectlon 2 6 4 Supervlslon

Thls paragraph requlres superv}s}on of all pneumat}c }nterconnects wMch are necessary for operation of the system Th~s requlrement means the nonpressur}zed actuation p}pe hose and tub}ng between expellant gas and remote actuator cartridges or cyl}nders have to be cont}nually monltored for the}r pneumat}c integrlty Thls requirement is impractlcal and unnecessary FEMA recommends tMs paragraph be amended by addlng an Except}on to read as follows

2 6 4 Superv~slon (paragraph wordlng as I t appears }n the Commlttee Report)

Exceptlon Pneumatic l}nes wMch are not cont}nuously pressur}zed shall be exempt from thls requlrement

/ !

"x

66

17 2 (2-3 4 (New)) Accept in Principle SUBMITTER Technical Committee on Dry Chemical Ext~nguishng

RECOMMENDATION Add new 2 3 4 as follows 2 3 4 Where ext~ngu~shlng systems are used to protect exhaust

systems for the removal of smoke and grease-laden vapors from commercial coohng equipment a slngle area shall ~nclude

(a) The hood or hoods connected by a common plenum all cooking equipment beneath the hoods and all duct wo~rk w~th~n 125 running f t of duct from any hood served and !

(b) Any other hoods cooking equipment and duct work ~nterconnected by a common duct from another hood and connected by less than 125 running f t of duct from the common point of connection (See Figure 2-3 4 )

BOTH A AND B MUST BE 125 FEET TO CLASSIFY AS SEPARATE HAZARD AREAS IF EITHER A" OR

B" IS LESS THAN 125 FEET BOTH PORTIONS ARE

TO BE CONSIDERED A SINGLE HAZARD AREA

F~gure 2 3 4

SUBSTANTIATION When Section 7 3 of NFPA 96 Standard for the Installatlon of Equipment for the Removal of Smoke and Grease-Laden Vapors from Commerclal Cooking Equipment ~s deleted ~n accordance wlth the d~rect~on of the Standards Counc~l a specific definition of s~ngle hazard area that applies to commerclal hoods should be inserted ~n Standard 17 COMMITTEE ACTION Accept in Principle

Add the follow~ng to existing Section 2-3 1 Any hazard which w~ll allow f l re propagation from one area to

another shall constitute a s~ngle f i re hazard Exception See Chapter 6 for pre englneered systems

COMMITTEE COMMENT Th~s change covers the ~ntent of the proposal

17 5 (2 5 4 3) Reject SUBMITTER Kenneth Faulstlch General Servlces Administration ~ A T I O N Change wording of Section 2-5 4 3 and renumber Section 2 5 4 3 to 2 5 4 4 New wording would be as follows

2 5 4 3 Approval tests for pre englneered local application systems shall ~nclude an actual d~scharge of the dry chemical agent Suitable bags shall be provided at each d~scharge nozzle to collect the agent The weighted amount of the agent for each bag shall be wlth~n 10 percent of the calculated amount SUBSTANTIATION My experience as the representative of the authority hawng jurisdiction in the testing of these systems has shown that many systems fal l to d~str~bute the agent ~n accordance with the ~nstaller s calculations Some nozzles may only receive a m}n~maI amount of agent thus possibly allowlng a f l re to spread without being extinguished No ext~ngulsh~ng system can be adequately tested w~thout a proper d~scharge test COMMITTEE ACTION Reject COMMITTEE COMMENT After considerable d~scuss~on the Commlttee unanimously rejected the proposal for the following reasons

1 D~fferent nozzles wlth~n the same system have d~fferent flow rates based on the type of agent and baslc design of the system

2 Th~s approach is too subjectwe to the expertlse of the person wltnesslng the test

3 There ~s no basts for selecting 10 percent as a measure of adequate performance

4 Back pressure caused by the gathering bags could adversely affect the d~str~but~on and quantity of the agent

5 I f pre englneered systems are ~nstalled according to hst~ng requirements ~t ~s only necessary to verify that the p~plng and nozzles are unobstructed

6 Engineered systems d~scharge rates are proprietary ~nformat~on

7 The Committee feels that Section 2-5 4 adequately covers the Submltter s concerns

17- 1 (2-6 3 3) Accept SUBMITTER Dennis P Nolan Wackenhut Serwces Inc RECOMMENDATION Statement of Problem The dry chemcal system s operating devices may be designed located or installed where they would be subject to mechanical or environmental conditions which would cause ~nadvertant actuation and dump of the dry chemcal agent

Rewse the last sentence in Section 2-6 3 3 f r o m conditions that would render them ~noperatlve to conditions that would render them ~noperat~ve or cause inadvertant operation of the system

SUBSTANTIATION Due to the APOLLO launch blast wbratlon experlenced at launch complexes}LC 39A and LC 39B Kennedy Space Center Florida dry chemical f l re protection systems ~n the subject areas were ~nadvertantly actuated Subsequent~ally the dry chemical s operating mechanisms had to be modlf~ed ~n order to prevent ~nadvertant actuatlon from such extenswe wbrat~on COMMITTEE ACTION Accept

17 6 (2-6 4 1 (New)) Accept ~n Principle SUBMITTER V~c D Humm V~c Humm & Assoclates RECOMMENDATION Add new section 2-6 4 1 as follows

2 6 4 1 When an existing building or a new build,of ~s prowded w~th a f l re alarm system The actuation of the dry chemical system power supervision and control panel trouble shall be connected to alarm and superwsory s~gnals Refer to Sectlon 2 6 for appropriate referance to other NFPA standards SUBSTANTIATION An extinguishing system ~n whatever form should alert the occupants of the bu~Idlng ut~l~zlng the protectwe slgna1~ng system Normally actuation of such a system means a ~ re or danger COMMITTEE ACTION Accept ~n Principle

Section 2-6 4 has been rewsed as shown ~n Section 2-6 4 of the rewr~te of NFPA 17 ~n th~s TCR COMMITTEE COMMENT The changes cover the ~ntent of the proposal

17 3 - (2 8 1 2) Accept in Prlnclple SUBMITTER W D Lease Jr Lease AFEX Inc ~ A T I O N Delete entire paragraph as wrltten and replace wlth the followlng

2 8 1 2 Tublng may be used for dlstrlbutlon of dry chemlcal agent Tubing shall be of JIC welded hydraullc constructlon wlth a mlnlmum burst strength of 3000 PSI In the slze ut11~zed F1ttlngs shall be compresslon type only wlth a burst strength of 3000 PSI and of the fu l l bore type All bends shall be smooth and free of klnks and restrlct~ons mlnlmum bend radius shall be as speclf~ed by the f l re extlngulshlng system manufacturer and/or l lstlng agency SUBSTANTIATION The us~ of properly deslgned and installed steel tublng dlstrlbutlon systems does not compromse and may enhance system function Greater reslstance to wbrat~on makes i t superlor to schedule 40 p]pe installatlons for hlgh wbratlon Installatlons Its noncombustlble and nonagmg (due to beat) characterlstlcs make i t superlor to hose installat~ons

Current state of the art capab111tles in hydraullc tublng and f~tt~ng manufacture Ind~cate ~nclus~on as perm~ssable means of dry chemcal dlstrlbutlon Use of such tubing and f l t t lngs for major hydraulic installatlons is wldely accepted by a dwerse collection of industr]es the ab111ty to withstand pressure surges wbratlon and shock has been hlstorlcally demonstrated

Lease AFEX Inc pioneered the wldespread use of steel tublng dlstrlbutlon systems For off h~ghway f i re protectlon Excepting corroslon thls environment is the most abuslve for commerc}al and ~ndustrlal f l re protectlon systems In eleven years of use steel tubing and compression-type f l t t lngs have enjoyed a v i r tual ly unblemlshed serwce record ~n w~dely d~vers~f~ed appl}catlons (Specific data is available on request )

In summary steel tublng of proper specification and w~th correct ~nstallatlon ~s compatible w~th dry chemcal d~str~butlon Proh~blt~on of ~ts use appears unwarranted and unnecessarily restrlcts system design and function Therefore for the benefit of the consumer we respectfully request the modlflcatlon proposed COMMITTEE ACTION Accept ~n Pr~nclple

Committee Action on th~s proposal ~s to accept ~n principle the recommended use of tubing and to delete exlst~ng Section 2 8 1 2 A new section (tentatively numbered 2 g 1 5) wil l be added to read as follows

Other p~pe or tubing which has been ~nvestlgated and llsted for th~s serwce may be used The use of such p~pe or tubing shall ~nvolve careful cons~deratmn of the following factors

(a) Pressure ratlng l~I Corroslon - chemlcal and electrolytlc

Joining methods l~I Avallabll~ty of f~tt~ngs

Resistance to f~re exposure and rapid temperature change (f) Flow characteristics

COMMITTEE COMMENT Th~s change covers the ~ntent of the proposal

17- 4 - (4 4 1 2 through 4 4 3 2 (New)) Reject SUBMITTER Harlan Lunt Oleans Fire & Safety ~ A T I O N Add to NFPA 17 Sectlon 4 4 1 2 4 4 1 3 4-4 2 4 4 3 and 4-4 3 2 from NFPA 10

Change wordlng from Extlngulsher to Cyllnder SUBSTANTIATION Six year malntenance should be performed on all Dry Chemical Cyllnders due to caklng lumplng and ~exposure to the elements Especlally systems whlch protect self servlce gas statlons I thlnk systems should be subject to slx year malntenance even more so than portable extlngulshers whlch for the most part are located ~n a controlled atmosphere

6 7 I

NFPA 17 COMMITTEE ACTION Re3ect COMMITTEE COMMENT The proposal is not clear The Committee feels that maintenance requlrements are adequately covered in the exlstlng standard The question of maintenance has already been submitted to the exlstlng maintenance Subcommittee

17- 7 (Entire Standard) Accept SUBMITTER Technical Committee on Dry Chemical Extlngulshlng Systems RECOMMENDATION Completely revise NFPA 17 1980 to update the document in the area of ~nspectlon maintenance plplng supervls~on and to add a new Chapter 6 on pre-englneered systems SUBSTANTIATION To cover the timely updating of the standard ~ O N Accept

Standard for

Dry Chemlcal Extlngulshlng Systems

NFPA 17 1985

NOTICE An asterisk (*) following the number or letter des~gnatlng a subd~vlslon ~ndlcates explanatory material on that subdivision in Appendix A

Informatlon on referenced publlcatlons can be found in Chapter 7 and Appendlx B

Chapter I Admnlstratlon

I-1" Scope This standard includes mlnlmum requlrements for dry chemical f i re extinguishing systems which discharge dry chemical from fixed nozzles or hand hose lines by means o~ expellant gas I t contains only the essentials and suggestions to make the standard workable in the hands of those skilled in this f ield Portable dry chemical equlpment is covered in NPPA 10 Standard for the Installation Malntenance and Use of Portable Fire Extlngu~shers

1 2 Purpose This standard is prepared for the use and guidance of those charged wlth the purchasing designing ~nstalllng testlng ~nspect~ng approving llst~ng operating or malnta~nlng of dry chemcal f i re extlngulshlng systems in order that such equipment wil l function as intended throughout ~ts l~fe Nothing in th~s standard is ~ntended to restrict new technologies or alternate arrangements prowdlng the level of safety prescribed by the standard Is not lowered

1-2 1 Only those skilled in this f ield are competent to design and install this equipment I t may be necessary for many of those charged with the purchaslng inspecting testing approving operating and maintaining thls equipment to consult an experlenced f i re protection englneer competent in this f~eld in order to effectively discharge their respective duties

1 2 2 Arrangement This standard ~s arranged as follows

Chapter 1 Administration

Cha~ter 2 - General Information and Requirements

Cha)ter 3 Total Flooding Systems

Cha)ter 4 - Local Application Systems

Cha)ter 5 - Hand Hose Line Systems

Cha~ter 6 - Pre Engineered Systems

Cha)ter 7 - Mandatory Referenced Publications

Appendix A Explanatory j

Appendix B Informatory Referenced Publications

i-3 Defln~t~ons For the purpose of clarlf lcatlon the following general terms used with special technlcal meanings in this standard are defined

Approved means acceptable to the authority hawng jurisdiction NOTE The National Fire Protection Association does not approve ~nspect or certlfylany installatlons procedures equipment or materials nor does i t approve or evaluate testing laboratories In determlnlng the acceptab11~ty of installatlons or procedures equipment or materials the authority having jurlsdlctlon may base acceptance on compliance with NFPA or other appropriate standards In the absence of such standards sa~d authority may require evidence of proper installation procedure or use The authority having jurlsdlctlon may also refer to the llstlngs or labeling practices of an organlzatlon concerned w~th product evaluatlons whch is in a position to determine compllance with appropriate standards for the current production of listed items

NFPA 17

Authority Having Jurlsdlctlon The authority having jurisdiction is the organlzatlon office or indlvldual responsible for approving equipment an installation or a procedure

NOTE The phrase authority having Jurlsdlctlon is used in NFPA documents in a broad manner since jurlsdlctlons and approval agedcles vary as do their respon~lbllltles Where

public safety is prlmary the authority having jurlsdlctlon may be a federal state local or other regional department or lndlvldual such as a f i re chief f i re marshal chief of a f l re prevention bureau labor department health department building of f lc la l electrlcal inspector or others having statutory authority For insurance purposes an insurance inspectlon department rating bureau or other insurance company representative may be the authorlty ~avlngIjurlsdlctlon In many circumstances the property owner or his designated agent assumes the role of the authority having jurlsdlctlon at government installations the commanding officer or departmental of f lc lal may be the authority having jurlsdlctlon

Auxiliary Equipment Listed equipment used in conJunction with the dry chemical systems 1 e to shut down power fuel or ventllatlon to the hazard being protected or to in l t late signaling devices

Caking A phenomenon that occurs when moisture chemically reacts with a dry chemlcal f l re extlngulshlng agent This reaction results in materials that being hydrated by moisture stick together to form a large agglomerate or what is more commonly referred to as lumps For the purpose of this standard lumps are deflned as those that do not crumble into particles when dropped from a height of 4 in (101 mm) onto a hard surface

Calculation and Design The process of computlng wlth the use of equations graphs or tables the system characterlstlcs such as flow rate pipe size area or volume protected by each nozzle

I nozzle pressure and pressure drop Th~s lnformatlon Is not required for listed pre-englneered systems since these systems must be installed in accordance with thelr pretested limitations described in the manufacturer s lnstallatlon manual

I Dry Chemlcal A powder composed of very small partlcles usually

of sodlum blcarbonate potassium bicarbonate urea based potassium bicarbonate potassium chloride or monoammonlum phosphate with added partlculate materlal supplemented by special treatment to prowde reslstance to packlng resistance to moisture absorption (caklng) and the proper flow capabilities

Dry Chemical System A supply of dry chemical whlch can be automatically or manually activated to dlscharge through a dlstrlbutlon system onto or into the protected hazard The system may also include aux111ary equlpment

Engineered Systems Those requiring individual calculatlon and deslgn to determine the flow rates nozzle pressures pipe slze area or volume protected by each nozzle quantltles of dry chemical and the number and types of nozzles and thelr placement in a specific system ~

Inspection Inspection ~s a quick check to give reasonable assurance that the extlngulshlng system is fu l ly charged and operable This is done by seeing that the system is in place that i t has not been actlvated or tampered wlth and that there is no obvlous physical damage or condltlon to prevent operation

Listed Equipment or materials included in a l l s t published by an organlzatlon acceptable to the authority having jurlsdIctlon and concerned wlth product evaluation that mal~talns periodic lnspectlon of production of listed equipment or materials and whose l lstlng states either that the equipment or material meets appropriate standards or has been tested and found suitable for use in the speclfled manner

NOTE The means for identlfylng listed equipment may vary for each organization concerned with product evaluation some of which do not recognize equlpment as listed unless ~t ~s also labeled The authority hawng jurisdiction should ut i l ize the system employed by the l lstlng organization to identlfy a llsted product

Maintenance Maintenance is a thorough check to give maximum assurance that the extlngulshlng system wil l operate as intended I t includes a thorough examlnatlon and any necessary repair or replacement of system components

Multlpurpose Dry Chemical Usually ammonium phosphate-based is effective on fires involving both ordinary combustibles such as wood or paper and flres in flammable liquids

Pre-Englneered Systems Those having predetermlned flow rates nozzle pressures and quantltles of dry chemical These systems have the specific pipe slze maximum and mlnlmum pipe lengths f lexlble hose speclflcatlons number of f l t t lngs and number and types of nozzles prescribed by a testlng laborator~ The hazards protected by these systems are speclflcally llmlteo as to type and slze by a testing laboratory based upon actual f l re tests Llmltatlons on hazards which can be protected by these systems are contained in the manufacturer s installatlon manual which is referenced as part of the l lst lng

68

NFPA 17

Shall Indicates a mandatory requlrement

Should Indicates a recommendation or that which is adwsed but not required

Testing A functional test of all components to verify operation of the system design and Installat~on

I-4 Units ~ Metric unlts of measurement in th~s standard are in accordance w~th the modernized metric system known as the International System of Units (SI) (See ASTM E380 Standard for Metric Practice )

1-4 1 I f a value for measurement as g~ven In th~s standard is followed by an equivalent value ~n other units the f~rst stated ~s to be regarded as the requirement A g~ven equivalent value may be approximate

1-4 2 The converslon procedure for the SI units has been to multlply the quantity by the conversion factor and then round the result to the appropriate number of s~gn~flcant dig~ts

Chapter 2 General Informatlon and Requirements

2 i * Dry Chemical The type of dry chemical used ~n the system shall not be changed unless proved to be changeable by a testing laboratory recommended by the manufacturer of the equipment and approved by the authority hawng jur~sdlct~on Systems are designed on the bas~s of the flow and extinguishing characteristics of a spec~flc make and type of dry chemlcal

CAUTION Types of dry chemical shall not be m~xed M~xtures of certain dry chemicals w~ll generate dangerous pressures and w~ll form lumps

2-2 Use and L~mtatlons

2 2 1" Use Types of hazards and equipment whlch can be protected using dry chemical extlnaulsh~ng systems ~nclude the following

(a) Flamable or combustible l~qulds and combustible gases

CAUTION Extlngulshment of uncontrolled d~scharge of flammable llqulds or combustible gases may result ~n a subsequent exploslon hazard

(b) Combustible solids hawng burnlng characteristics s~m~lar to naphthalene and p~tch which melt when ~nvolved ~n f~re

(c) Electrical hazards such as transformers or o~l c~rcu~t breakers

(d) Textile operations subject to flash surface f~res Where b~carbonate based dry chemical is used water shall be provided to extlngu~sh possible smoldering or deep seated f l re

(e) Ordinary combustibles such as wood paper or cloth uslng multipurpose dry chemcal when i t can reach all surfaces ~nvolved ~n combustion

(f) Restaurant and commercial hoods ducts and assoclated ~cooklng appliance hazards such as deep fat fryers (See also 4 4 and A 2-I(3) ) For other specific details see NFPA 96 Standard for the Installatlon of Equipment for the R~moval of Smoke and Grease-Laden Vapors from Cornmerclal Cooking Equipment

(g) Some plastics depending upon the type of mater~al and ~ts conf~gurat~o#of hazard For more specific }nformat~on consult the manufacturer of the equipment

2-2 2 L~m~tat~ons Dry chemical extinguishing systems shall not be considered satisfactory protection for the follow~ng

(a) Chemicals containing their own oxygen supply such as cellulose nltrate

(b) Combustible metals such as sodium potassium magnesium t~tanium and zlrcon~um Dry powder systems l~sted by a testing laboratory for combustible metal f~res may be used

(c) Deep-seated or burrowing f~res ~n ordinary combustlbles where the dry chemical cannot reach the point of combustion

2-2 2 1 Before dry chemical ext~ngu~shlng equipment ~s considered for use to protect electronlc equipment or delicate electrical relays the effect of residual deposits of dry chemical on the performance of thls equipment shall be evaluated

2-2 2 2 Multipurpose dry chemical shall not be consldered satisfactory for use on machinery such as carding equipment in text i le operations and del~cate electrical equipment because upon exposure to temperatures ~n excess of 250OF (121oc) or relative humldlty in excess of 50 percent deposits w~ll be formed whch may be d~ff~cult to remove

\ /

69

NFPA 17

2 2 2 3* Dry chemlcal when dlscharged w111 d r l f t from the ln~nedlate dlscharge area and settle on surroundlng surfaces Prompt cleanup w~ll mln~m~ze posslble sta~nlng or corroslon of certaln materlals whlch may take place in the presence of molsture

2-3 Systems Protectlng One or More Hazards

2 3 1 Where in the oplnlon of the authority havlng jurlsdlctlon two or more hazards may be slmultaneously involved in f l re by reason of their proxlmlty the hazards shall be protected by ind~vldual systems ~nstalled to operate slmultaneously or by a slngle system deslgned to protect all hazards that may be slmultaneously involved Any hazard whlch w111 allow f l re propagatlon from one area to another shall constltute a single f i re hazard

Exceptlon See Chapter 6 for pre-englneered systems

2-3 2 Where hand hose lines may be used on a hazard that is also protected by a flxed system separate dry chemlcal supplles shall be provlded

Exception I f a slngle dry chemical supply is used for both a hand hose llne system and a flxed nozzle system the hazards protected by the two systems shall be separated so that the hand hose llnes cannot be used on the hazard protected by the flxed nozzle system

2 4* Personnel Safety

2-4 1 Safety Requlrements In total floodlng and local appllcatlon systems where there is a posslb111ty that personnel may be exposed to a dry chemcal dlscharge sultable safeguards shall be prowded to ensure prompt evacuation of such locations and also to prowde means for prompt rescue of any trapped personnel Such safety ~tems as personnel training warning s~gns d~scharge alarms predlscharge alarms and resplratory protection shall be considered

CAUTION Hazards to Personnel The dlscharge of large amounts of dry chemcal may create hazards to personnel such as reduced vlslb111ty and temporary breathlng d l f f l cu l ty

2 4 1 1 When dry chemlcal pressure contalners are not attached to plplng or hand hose llnes the dlscharge outlet shall be prowded wlth a protectlve dlffuslng safety cap to protect personnel from recoll and h~gh flow dlscharge in case of accldental actuatlon Such protectlve caps shall also be used on empty pressure containers to protect threads These caps shall be provlded by the manufacturer of the equipment

2-4 2 Electrical Clearances All system components shall be so located as to malnta~n mlnlmum clearances from l~ve parts as shown In the followlng table

As used in thls standard clearance ~s the alr d~stance between dry chemlcal equipment ~ncludlng p~p~ng and nozzles and unenclosed or un]nsulated l~ve electrical components at other than ground potential

The clearances g~ven are for altltudes of 3 300 f t (1000 m) or less At altitudes in excess of 3 300 f t (1000 m) the clearance shall be ~ncreased at the rate of 1 percent for each 330 f t (100 m) ~ncrease ~n altitude above 3 300~ft (1000 m)

The clearances are based upon m~nlmum general practlces related to design Baslc Insulation Level (BIL) values To coordlnate the required clearance w)th the electrical deslgn the design BIL of the equipment being protected shall be used as a bas~s although thls ~s not mater~al at nominal l~ne voltages of 161 kv or less

Up to electrical system voltages of 161 kv the design BIL kv and correspondlng m~nlmum clearances phase to ground have been established through long usage

At voltages higher than 161 kv uniformity ~n the relationship between design BIL kv and the various electrical system voltages has not been established in practice and ~s dependent upon several variables so that the required clearances to ground shall be based upon the deslgn BIL used rather than on the nomlnal l~ne or ground voltage

Possible design variations ~n the clearance required at h~gher voltages are ewdent ~n Table 2 4 3 where a range of voltages ~s ~nd~cated opposlte the various BIL test values ~n the hlgh voltage port~on of the table However the clearance between un~nsulated energized parts of the electrical system equipment and any port~on of the dry chemical system shall' be not less than the mn~mum clearance prowded elsewhere for electrical system ~nsulatlon on any ~nd~wdual component

NFPA 17 V Table 2-4 3 Clearance from Dry Chemical Equipment

To L~ve Un~nsulated Electrical Components

Nomnal L~ne Nominal Voltage" Voltage To Ground Design BIL Minimum Clearance*

kv kv kv ~n mm

15 9 110 7 178 23 13 150 10 254 34 5 20 200 13 330 46 27 250 17 432 69 40 350 25 635

115 66 550 37 940 138 80 650 44 1118 161 93 750 52\ 1321 196-230 114-132 900 63 1600

1050 76 1930 287-380 166 220 1175 87 2210

1300 98 2489 1550 120 3048

500 290 1675 131 3327 I 1800 142 3607 500-700 290-400 1925 153 3886

2100 168 4267 2300 184 4674

NOTE BIL values are expressed as k~lovolts (kv) the number being the crest value of the ful l wave ~mpulse test that the electrical equipment ~s designed to w~thstand

*For voltages up to 69 kv the clearances are taken from the NFPA 70 NATIONAL ELECTRICAL CODE •

2 5 Spec]f~catlons Plans and Approvals

2-5 1 Specifications Specifications for dry chemical f~re ext)ngu~shlng systems shall be drawn up w~th care under superws]on of a competent person~ and w~th the adwce of the authority hawng Jurisdiction To ensure a satisfactory system the following items shall be ~n the specifications

2-5 1 1 The speclflcat~ons shall designate the authority hawng jurlsd~ctlon and ~nd~cate whether plans are required

2-5 1 2 The specifications shall state that the }nstallat~on shall conform to thls standard and meet the approval of the authority hawng jurisdiction

2-5 1 2 1 The specification shall ~nd~cate that only l~sted equipment from a s~ngle manufacturer shall be used

Exception Speclal auxiliary dewces acceptable to the manufacturer and the authority hawng jur~sdlct~on may be used

2-5 1 3 The specifications shall ~nclude the specific tests that may be required I f anF to meet the approval of the authority hawng jurisdiction and indicate how the cost of testing ~s to be borne

2 5 1 4 These specifications shall ~nd~cate the hazard to be protected and shall ~nclude such ~nformat~on as physical d~mens~ons combustlbles alr handling equipment heat sources etc

2-5 2 Plans Where~lans are required the responslb]l~ty for their preparation shall be entrusted only to competent persons

2-5 2 1 These plans shall be drawn to an ~nd~cated scale or be suitably d~mens]oned and shall be made so that they can be eas~ly reproduced

2-5 2 2 These plans shall contaln sufficient deta~1 to enable the authority having jur~sd]ctlon to evaluate the hazard or hazards and to evaluate the effectiveness of the system The details on the hazards shall ~nclude materials ~nvolved the location and arrangement and the exposure to the hazard

2°5 2 3 The detalls on the system shall include sufflclent informat~on and calculations on the amount of dry chemical the s~ze length and arrangement of connected piping or piping and hose description and location of nozzles so that the adequacy of the system can be determined Flow rates of nozzles used shall be prowded for engineered systems Information shall be submtted pertaining to the location and function of detection dewces operating devices auxiliary equipment and electrical clrcu~try i f used Sufficient information shall be ind~cated to ~dent~fy properly the apparatus and dewces used

2-5 3 Approval of Plans Where plans are required they shall be submitted to the authority hawng jurisdiction for approval before work starts

2 5 3 1 Where f leld cond~tlons necessitate any substantlal change from the approved plan the corrected as-~nstalled plans shall be submitted to the authorlty hawng jurisdiction for approval

J NFPA 17 2 5 4 Approval of Installatlons The completed system shall be tested by quallfled personnel as required by the authorlty havlng jurlsdlctlon These tests shall be adequate to determlne that the system has been properly installed and w111 functlon as intended Only listed equlpment and devices shall be used in these systems

2-5 4 1 The Installer shall cer t l fy to the authorlty havlng jurlsd~ctlon that the installatlon has been made In accordance wlth the approved plans and the l~stlng of a testlng laboratory

2-5 4 2 The approval tests shall include a dlscharge of dry chemlcal ~n sufflclent amounts to verlfy that the system ~s properly ~nstalled and functional The method of verlf lcatlon shall be acceptable to the authorlty havlng jurlsdlctlon Piplng shall not be hydrostatlcally tested Where pressure testlng is requlred I t shall be by means of a dry gas The labellng of devices wlth proper deslgnatlons and instructlons shall be checked

2-5 4 3 After any dlscharge of dry chemlcal care shall be taken to see that all p~plng and nozzles have been blown clean using compressed dry alr or nltrogen ~f necessary Care also shall be taken to see that the system ~s properly charged and placed in the normal set condition

2-6 Operatlon and Control of Systems See NFPA 71 Standard for Central Statlon S1gnallng Systems NFPA 72A Standard for Local Protectlve S1gnallng Systems NFPA 72B Standard for Aux111ary Protectlve S1gnallng Systems NFPA 72C Standard for Remote Statlon Protectlve S1gnallng Systems NFPA 72D Standard for Proprietary Protectlve S1gnallng Systems and NFPA 72E Standard for Automatic Fire Detectors as applicable to detectlon alarm and control functlons for dry chemlcal extlngulshlng systems

2 6 1 Methods of Actuatlon Systems shall be classlfled as automatlc or manual in accordance wlth the following methods of actuation

(a) Automatic Operatlon Operatlon that does not requlre any human action

(b) Normal Manual Operatlon Operatlon of a system requlrlng human actlon where the dewce used to cause the operatlon ~s located near the hazard so as to be easily accessible at all tlmes (see 2 6 3 4) Operatlon of one control shall be all that is requlred to bring about the fu l l operatlon of the system

(c) Emergency Manual Operation Operat}on of the system by human means where the dewce used to cause operation ~s fu l ly mechanlcal ~n nature and is located on the dewce belng controlled or on ~ts mounting assembly Fully mechanical may ~ncorporate use of the system pressure to complete operation of the dewce

2-6 2 Detection of F~res F~res or conditions l~kely to produce f~re shall be detected by v~sual (human senses) or by automatic means

2-6 2 1 Reliance on wsual detectlon shall be permitted only w~th perm~sslon of the authority hawng aur}sd~ct~on where f~res or conditions l}kely to produce flres can be read~ly detected by such means

2 6 2 2 Automatic detection shall be by a l~sted or approved dewce that ~s capable of detecting and ~ndlcatlng heat flame smoke combustible vapors or an abnormal condition ~n the hazard such as process trouble that ~s l~kely to produce f~re

2-6 3 Operating Dewces Operating dewces shall mean expellant gas releasing mechanisms dry chem}cal dlscharge controls and shutdown equ}pment

2-6 3 1 Operation shall be by l~sted mechanlcal electrical or pneumatic means

2 6 3 2 At1 operating dewces shall be deslgned for the serwce they wil l encounter and shall not be readily rendered ~noperatlve or susceptible to accidental operation Dewces shall be normally designed to function properly from 40°F to +150°F (-40°C to +65 6°C) or marked to ~nd~cate temperature l~m]tat~ons

2-6 3 3 All dewces shall be designed located ~nstalled or protected so that they are not subject to mechanical enwronmental or other cond t~ons that would render them inoperat~ve or cause ~nadvertent operation of the system

2-6 3 4 At least one manual control for actuation shall be located no more than 5 f t ( I 5 m) above the floor and be conveniently and easily accessible at all t~mes ~nclud~ng the time of f~re

2-6 3 5 All valves controlling the release and d~strlbut~on of dry chemical shall be prowded with an emergency manual control

/ Exceptlon No I Th~s does not apply to slave cylinders

Exception No 2 I t ~s posslble for the normal manual control to qualify as emergency manual control I f prows]ons of Section 2-6 are satisfied

70

NFPA 17

6 3 6 Manual controls shall not require a pull of more than 40 Ib (178 newtons) (force) nor a movement of more than 14 In (356 mm) to secure operation

2-6 3 7 Means shall be provided for checking the amount of expellant gas to assure that i t ~s sufflclent for the proper operation of the system

2-6 3 8 All shutdown dewces shall be considered integral parts of the system and shall function with the system operation I f the expellant gas ~s used to pneumatically operate these devices then the gas must be taken prior to ~ts entry into the dry chemlcal tank

2-6 3 9 All remote manual operatmg dewces shall be ~dent~f~ed as to the hazard that they protect

2-6 4 Superws~on Superwslon of electric or pneumatlc operated automatic systems shall be prowded unless specifically walved by the authority having Jur~sdlct~on

2 6 5* An alarm or ~nd~cator shall be prowded to show the system has operated that personnel response may be needed and that the system ~s ~n need of recharge The ext~ngu~shlng system shall be connected to the alarm system ~f prowded ~n accordance w~th the requirements of the appropriate s~gnahng system standard (NFPA 71 72A 72B 72C or 72D) so that actuat~op of the dry chemlcal system wil l sound the f~re alarm as well as prowde the functlon of the ext~ngulshlng system

Two sources of electrical power shall be prowded These shall consist of a primary (ma~n) supply and a secondary (standby) supply The primary (ma~n) power supply shall have a hlgh degree of rellab~l~ty adequate capaclty for the ~ntended serwce and shall consist of one of the following

(a) Light and po&er service

(b) Engine driven generator or equivalent

Secondary (Standby) Power Supply Capaclty and Sources The secondary (standby) supply shall be provided to supply the energy to the system under the maximum normal load for 24 hours and then be capable of recelvmg one f~re alarm s~gnal perslst~ng for flve mnutes ~n the event of a total power failure or low voltage condlt~on (less than 85 percent of the nameplate voltages) of the prlmary (ma~n) power supply The secondary (standby) power supply shall automatically transfer to operate the system wlthln 30 seconds of the loss of the primary (ma~n) power supply The secondary (standby) power supply shall consist of one of the followlng

(a) A storage battery wlth 24 hours capacity

(b) An englne-dr~ven generator

(c) Multiple automatlc starting englne driven generators capable of supplying the energy required w~th the largest generator out of servlce

Exception When acceptable to the authority hawng jurisdiction secondary (standby) power shall not be required to operatTthe evaGuatlon alarm ind~cat~ng appllances or other supplemental functlons not essentlal to the receipt of s~gnals at the maln control unit

These systems sh~ll be electr~cally superwsed so the occurrence of a s~ngle open or s~ngle ground fault condition of its ~nstallat~on w~r~ng whlch prevents the normal operation of the system or failure of the primary electric power supply w~ll be indlcated by a d~st~nct~ve trouble s~gnal

2 6 5 1 Alarms lnd~catlng failure of superwsed dewces or equlpment shall glve prompt and positive indication of any fa~lure and shall be dlst~nct~ve from alarms ind~cat~ng operation or hazardous condlt~ons

2-7 Dry Chemical and Expellant Gas Suppl7

2 7 1 Quantity The amount of dry chemical ~n the system shall be at least sufflc~ent for the largest single hazard protected or for the group of hazards whlch are to be protected simultaneously

2-7 2 Quahty The dry chemlcal used ~n the system shall be suppl~ed by the manufacturer of the equipment The character~stlcs of the system are dependent upon the composltlon of the dry chemcal and the type of expellant gas as well as upon other factors and therefore ~t ~s ~mperatlve to use the dry chemical prowded by the manufacturer of the system and the type of expellant gas specified by the manufacturer of the system

2-7 2 1 Where carbon d~ox~de or nltrogen ~s used as the expellant gas ~t shall be of good commerclal grade free of water and other contamnants that m~ght cause contalner corroslon

NFPA 17

2 7 2 2 Carbon dloxlde used as an expellant gas shall meet the followlng speclflcatlons

(a) The vapor phase shall be not less than 99 5 percent carbon dloxlde

(b) The water content of the llquld phase shall not be more than 0 01 percent by welght ( 30°F ( 34 4°C) dew polnt)

(c) 011 content shall not be more than 10 ppm by welght

2 7 3* Reserve Supply Where a dry chemlcal system protects multlple hazards by means of selector valves sufflcient dry chemcal and expellant gas shall be kept on hand forkone complete recharge of the system For single hazard systems a slmllar supply shall be kept on hand I f the ~mportance of the hazard is such that i t cannot be shut down untll recharges can be procured

2-7 4 Storage Storage of charglng supphes of dry chemlcal shall be in a constantly dry area and the dry chemlcal shall be contalned In metal drums or other contalners whlch w111 prevent the entrance of molsture even in small quantltles Prlor to chargmg the dry chemlcal chamber the dry chemlcal shall be carefully checked to determlne that i t is in a flowlng condltlon

2 8 Contalner The dry chemcal contalner and expellant gas assemblles shall be located near the hazard or hazards protected but not where they w111 be exposed to a f i re or exploslon in these hazards

2 8 1 The dry chemcal contalner and expellant gas assemblles shall be located so as not to be subjected to severe weather condltlons or to mechanlcal chemlcal or other damage When excesslve cllmat~c or mechanical exposures are expected suitable enclosures or guards shall be prowded

2 8 2 The dry chemlcal contalner and expellant gas assemblles ut~llzlng nltrogen shall be located where the amblent temperature is normally between 40OF and 120OF (-40Oc and 48 9Oc) Assemblles ut~llzmg carbon dlox~de shall be located where the amblent temperature is normally between 32OF and 120OF (OOC and 48 9°C) I f temperatures are outside these l lmts the equipment shall be l~sted for such temperatures or methods shall be provlded for mahnta~nlng the temperatures w~thln the amblent ranges glven

NOTE Systems for use at hlgher or lower temperatures can be speclally deslgned

2 8 3 The dry chemlcal contalner and expellant gas assemblles shall be located where they wil l be easy to inspect malntaln and servlce

2-9 Distribution System

2 9 1" Pipe and Flttlngs Threaded plpe and f l t t lngs shall be galvanlzed malleable iron galvanlzed steel stamless steel copper or brass Black steel plpe wlth welded 3olnts or malleable Iron threaded f l t tmgs may be used when the atmosphere is relatlvely noncorroslve Speclal corros#lon resistant materlals shall be used for corroslve atmospheres When steel plpe ~ncorporat~ng welded 3omts or rolled groove f~tt~ngs Is used a mnlmum wall thickness of 0 188 ~n (5 mm) ~s permitted for pressures up to 300 ps~ (20 7 BAR) in slzes 4 ~n (101 mm) and larger For pipe slzes less than 4 ~n (101 mm) in welded or rolled groove p~pe systems a mm~mum wall thickness equivalent to Schedule 10 p~pe ~s permitted for pressures up to 300 pS~ When steel p~pe ~s jomed by threaded f~tt~ngs or by cut groove couplings the m~n~mum p~pe thickness shall be In accordance w~th Schedule 40 for pressures up to 300 psl Brass and copper p~pe shall be not less than the approxlmate Schedule 40 wall thickness (regular p~pe) for p~pe s~zes of 6 ~n (152 mm) or less

2 9 1 1 Cast ~ron p~pe and fltt~ngs shall not be used

2 9 1 2 Flexible p~p~ng (hose) shall be used only ~n accordance wlth the l~stlngs of a testlng laboratory as they are stated for specific dry chemical f l re ext~ngulsh~ng systems (See A-2-8 1 )

2 9 1 3 P~pmg for systems to be ~nstalled for protection of cryogenic l~qu~d sp~ll f~res shall be protected from submergence ~n the liquid IDcal~zed llqu~d ~mp~ngement and the simultaneous exposure to cryogenlc l~qu~d and flame temperatures Where the dry chemlcal supply l~nes are ~nstalled underground w~thln the potential sp~11 area the ~nd~wdual branch l~nes shall be brought up through insulated sleeves The ~nsulated sleeves shall be extended above the maximum anticipated cryogenlc l~qu~d accumulation depth Any subbranch~ng above grade shall also be protected agalnst local~zed ~mp~ngement by the cryogenlc liquid

2 9 1 4 Other types of pipe or tubing which have been ~nvestlgated and llsted for thls serwce may be used The use of such p~pe or tubing shall ~nvolve careful conslderat~on of the follow~ng factors

(a) Pressure rating

(b) Corrosion (chemical and electrolytic)

(c) Methods of Jolnlng

71

NFPA 17 (d) Avallab~hty of f~tt~ngs

(e) Reslstance to f l re exposure and rap~d temperature changes

(f) Flow characterlst~cs

2-9 2* Arrangement and Installation of P~pe and F~tt~ngs P}p~ng shall be installed ~n accordance w~th good commercial practices

2 9 2 ] A11 p~p~ng shall be la~d out to produce the desired dry chemical flow rate at the nozzles and care shall be taken to avoid posslble restrictions due to foreign matter and faulty fabr~catlon and/or ~mproper installatlon t _

2 g 2 2 The p~p~ng system shall be securely supported and shall not be subject to mechanical chemical or other damage Where explosions are posslble the p~p~ng system shall be hung from supports that are least hkely to be d~splaced

2 9 2 3 P~pe shall be reamed and cleaned before assembly and after assembly the entire p~plng system shall be blown out wlth dry gas before nozzles or d~scharge dewces are installed P~pe-thread compound or tape shall not be used

2 9 3 Valves A11 valves shall be l~sted for the ~ntended use partlcularly ~n regard to flow capacity and operation Selector valves shall be of the qu~ck-openlng type allowing essential free passage of the dry chemical w~thout restrlctlon

2-9 3 1 Valves shall not be~eas~ly subject to mechan)cal chemical or other damage

2-9 4 D~scharge Nozzles D~scharge nozzles shall be llsted for the use ~ntended in accordance w~th subsequent chapters

2-9 4 1 Discharge nozzles shall be of adequate strength for use w~th the expected working pressures

2-9 4 2 Discharge nozzles shall be of brass stainless steel or other corrosion reslstant materials or be protected ~nslde and out agalnst corrosion They shall be made of noncombustible materials and shall w~thstand the expected f~re exposure w~thout deformation

2 9 4 3 A11 nozzles shall be deslgned and subsequently located installed or protected so that they are not subject to mechanlcal enwronmental or other conditions that would render them ~noperat~ve

2 g 4 4 ~scharge nozzles shall be so connected and supported that they may not be readily put out of alignment Where nozzles are connected d~rectly to flexible hoses they shall be prowded w~th mounting brackets or flxtures to assure that they can be aligned properly and that the alignment w~ll be ma~ntalned

2 9 4 5 Discharge nozzles shall be clearly marked for ~dent~f~cat~on of type and s~ze

i 2 9 4 6 L~sted d~scharge nozzle assembl}es shall include protective caps or other suitable means to protect the p~p~ng from the entrance of molsture and forelgn materials

2-9 5 P~pe S~ze and Nozzle Determination Pipe s~zes and nozzles shall be selected on the bas~s of calculations to deliver the required dry chemical flow rate)at each nozzle or for pre engineered systems in accordance w~th llmltatlon~ set by a testlng laboratory

2-9 5 1 Equations or graphs derived therefrom shall be used to determine the pressure drop in the p~pe llne ~n englneered systems Th~s design ~nformat~on shall be based on tests performed by the manufacturer and conflrmed by a testing laboratory I t is not requlred ~n pre englneered systems

2 10 Electrical W~r~ng and Equipment

2-10 i* Installatlon Electrical wlr~ng and equipment shall be ~nstalled in accordance w~th NFPA 70 NATIONAL ELECTRICAL CODE

2 11 Inspection Maintenance and Recharglng

2 11 1 General The procedure for ~nspect~on maintenance and recharging of dry chemcal extinguishing systems varies conslderably M~n~mal knowledge ~s necessary to perform a monthly qu~ck check or monthly inspectlon ~n order to follow the

~nspect~on procedure as out1~ned ~n Section 2 11 2

A trained person who has undergone the }nstruct~ons necessary to reliably perform the maintenance and recharge serwce and has the manufacturer s servlce manual shall service the dry chemical f l re ext~ngulshlng system at intervals not more than s~x months apart as outhned ~n Section 2-11 3 !

2 11 2 Inspectlon

NFPA 17 2 11 2 1 On a monthly basls inspectlon shall be conducted in accordance wlth the manufacturer s manual As a mlnlmum thls qulck check or inspectlon shall include the following

(a) The extlngulshlng system is in its proper 1ocatlon

(b) Manual actuators are unobstructed

(c) Tamper indlcators and seals are intact /

(d) Malntenance tag or certlf lcate is in place

(e) No obvlous physlcal damage or condltlon exlsts whlch may prevent operation

(f) Pressure gage(s) i f provlded are in operable range

2 11 2 2 I f any deflclencles are found approprlate correctlve actlon shall be taken immedlately

2 11 2 3 Personnel maklng inspectlons shall keep records for those extlng~ish~ng systems that were found to requlre correctlve actlons

2-11 2 4 At least monthly the date the inspectlon was performed and the ~nltlals of the person performing the inspectlon shall be recorded

2-11 3 Malntenance

2 11 3 1 At least semlannually mamtenance shall be conducted in accordance w~th the manufacturer s maintenance manual As a mlnimum such malotenance shall conslst of the following

(a) Check to see that the hazard has not changed

(b) Examlne all detectors expellant gas container(s) agent contalner(s) releasing dewces plping hose assemblles nozzles alarms and all aux111ary equlpment

(c) Welgh or check pressure of expellant gas and agent contalners

(d) Examlne the Dry Chemlcal I f there is ewdence of caklng the dry chemlcal shall be dlscarded and the system shall be recharged ~n accordance w~th the manufacturer s Instructlons

t Exceptlon The dry chemcal in stored pressure systems does not require semiannual exam~natlon but shall be examlned at least every slx years

(e) When semannual maintenance of any dry chemcal chambers or system components reveals condltlons such as but not llmlted to corroslon or p~ttlng In exce~s of manufacturer s llm~ts structural damage or f l re damage repairs by solderlng weldlng or brazlng the affected part(s) shal~ be replaced or hydrostatlcally tested in accordance wlth the recommendations of the manufacturer or the orlglnal certlfylng agency or both The hydrostatlc testlng of dry chemlcal chambers shall follow the applicable procedures outhned in 2-10 1 7

(f) All dry chemlcal systems shall be tested whlch shall ~nclude a check of the detect~on~system alarms and releasing devlces ~ncludlng manual statlons and other assoclated equlpment A d~scharge(of the dry chemical is normally not part of th~s test

(g) When the malntenance of the system(s) reveals defective parts which could cause an impa}rment or failure of proper operation of the system(s) the affected parts shall be replaced or repaired in accordance wlth the manufacturer s recommendations

(h) The maintenance report wlth recommendations ~f any shall be f~led w~th the owner or w~th the designated party responsible for the system

2-11 3 2 Fixed temperature sensing elements of the fusible alloy type shall be replaced at least annually or more frequently ~f necessary to assure proper operation of the system

2 11 4 Recharging

2 11 4 1 All extlngulshlng systems shall be recharged after use or as lndlcated by an inspection or when performlng malntenance

2-11 4 2 Systems shall be recharged in accordance w~th the manufacturer s ~nstruct~ons

r 2 12 Hydrostatic Testing The followlng parts of dry chemical systems w~th dry chemical chambers of less than 150 Ib (68 kg) nominal capacity (based on sodlum b~carbonate agent) shall be hydrostatically tested at an interval not to exceed twelve years dry chemlcal chambers aux~l~ar X pressure containers valve assemblies hoses and f~tt~ngs (not includlng f~eld plp~ng) check valves d~rectlonal valves manifolds and hose nozzles The procedures shall be those approved by a laboratory for each type of equipment

(a) The dry chemical removed from the chamber prlor to testlng shall be d~scarded

72

NFPA 17

(b) Care shall be exercised to make certain that all equipment tested ~s thoroughly drled prior to recharging

(c) To protect the hazard during th~s operation ~f there is no automatic connected reserve alternate protection acceptable to the authorlty hawng 3ur~sdlctlon shall be provlded

Chapter 3 Total Floodlng Systems

3-i General In~ormatlon I

3 I 1 Definition A total flooding system means a supply of dry chemical permanently connected to f~xed p~p~ng wlth f~xed nozzles arranged to d}scharge dry chemlcal ~nto an enclosed space or enclosure about the hazard

3-I 2 Uses Th~s type of t system shall be used only where there is a permanent enclosure about the hazard that is adequate to enable the required concentration to be buil t up The total area of unclosable openings shall not exceed 15 percent of the total area of the s~des top and bottom of the enclosure

3 i 2 1 Cons~deratlon shall be g~ven to the el~mlnat~on of probable sources of re~gnlt~on because the extinguishing actlon of a dry chemical flooding system ~s transient

3-i 2 2 Deep-seated f~res ~nvolwng solids subject to smoldering shall be protected by multipurpose dry chemlcal systems where the dry chemical can reach all surfaces ~nvolved in combustion B~carbonate-based dry chemicals shall not be used for protectlon against thls type of f l re

3-i 3 General Requirements Total flooding systems shall be designed ~nstalled tested and maintained ~n accordance w~th the appl~cable rules ~n Chapter 2 and w~th the additional rules set forth ~n thls chapter

3 2 Hazard Specifications

3-2 I Enclosure In the deslgn of total flooding systems the character~stlcs of the enclosure shall be considered as follows

3 2 1 1 The total area of unclosable openings for which no compensation ~s prowded shall not exceed 1 percent of the total area of the s~des top and bottom of the enclosure Unclosable openings havlng an area ~n excess of 1 percent and not exceeding 5 percent shall be compensated for by the provision of additional dry chemlcal Unclosable openings hawng an area ~n excess of 5 percent of the total enclosure area and not exceeding 15 percent shall be screened by local app~catlon of addltlonal dry chemical (See 3 - 3 4 1 )

3-2 2 Leakage and Ventllat~on The leakage of dry chemical from the protected space shall be m~n~m~zed s~nce the effectlveness of the flooding system depends upon obtaining an extlngu~shlng concentration of dry chemical

\ 3 2 2 I Where possible openlngs such as doorways windows etc shall be arranged to close before or s~multaneously w~th the start of the dry chemical d~scharge or 3 3 4 1 shall be followed

3 2 2 2 Where forced-air ventllat~ng systems are ~nvolved they shall elther be shut down and/or closed before or s~multaneously w~th the start of the dry chemical dlscharge or 3 3 4 2 shall be followed

3-3 Dry Chemical Requirements and D~strlbut~on

3-3 I * General The following factors shall be considered ~n the total floodlng of enclosed spaces wlth dry chemical

(a) M~n~mum quantity of dry chemical required

(b) ~ M~n~mum rate of flow of dry chemical

(c) Spaclng l~m~tatlons of the nozzles

Exception In the case of pre-eng~neered systems the rate of flow n~ed not be considered slnce ~t is governed by the p~p~ng and nozzle l~mltatlons verlf~ed by a testlng laboratory See Chapter~6

3 3 1 1 The quantity of dry chemical and the flow rate shall be sufficient to create a f l re ext~ngulshlng concentration in all parts of the enclosure

3-3 1 2 The nozzles shall be placed so as to provide not less than the m~n~mum design concentration of dry chemical in all parts of the enclosure For f~res ~n ordlnary combustlbles where multipurpose dry chemical shall be used for protection additional dry chemical applied by local appl~catlon may be required in order to protect adequately all exposed surfaces

3-3 I 3 The nozzles shall be located so that th~ d~scharge w~ll not be obstructed

3-3 2 Volume Allowances In calculating the net volume to be protected allowance shall be permitted for permanently located structures etc that mater~ally reduce the volume

NFPA 17

3 3 3 Rate of Appllcatlon In englneered systems the mlnlmum deslgn rate of appllcatlon shall be based on the quantlty of dry chemical and the maximum t~me to obtain the deslgn concentratlon

Exception Inpre englneered systems these factors are established for speclf~c volume and other cond~tlons glven ~n the l~st~ng of such systems by testing laboratories (See Chapter 6 and A 3 3 1 )

3-3 3 1 In engineered systems the rate of appl~catlon shall be such that the deslgn concentration ~n all parts of the enclosure shall be obtained w~th~n 30 seconds

3-3 4 Compensation for Special Condlt~ons Additional quantities of dry chemlcal and additional nozzles ~f necessary shall be prowded to compensate for any speclal condition that may adversely affect the extlngu~sh~ng effectiveness of the system

3-3 4 1 Unclosable openlngs hawng areas ~n excess of 1 percent of the total area of the sldes top and bottom of the enclosure and not exceeding 5 percent shall be compensated for by the use of supplemental dry chemical ~n the proportions of not less than 0 5 Ib per sq f t (2 44 kg/m 2) of unenclosed opening applied through the regular dlstr~but~on system When the unclosable openlngs have areas exceeding 5 percent of the total of the sides top and bottom of the enclosure and not exceeding 15 percent compensation shall be furnished by addltlonal dry chemical ~n the proportion of not less than i Ib per sq f t (4 88 kg/m ~) of unclosed openlng applied simultaneously by location application over the openlngs A system that ~s l~sted by a testlng laboratory for or ~nclud~ng protection of unclosable openings may be used in l~eu of the above

3 3 4 2 For vent~latlng systems that w~ll not be shut down supplementary dry chemical shall be added to the protected volume through the regular d~str~but~on system The supplementary dry chemical shall be added at the point or polnts of air ~nlet and shall be in proportlon to the volume of alr removal during the period of dry chemcal d~scharge calculating as i f ~t were ~dd~t~onal volume to be protected

Exception Prelenglneered systems l~sted for restaurant hood and duct protection are suitable for use with or w~thout shutdown of the vent~latlon system or closure df dampers See Chapter 6

Chapter 4 Local Appllcatlon Systems

4-1 General Informatlon

4-I I Deflnlt~on A local appllcatlon system means a supply of dry chemlcal permanently connected to a system of flxed plplng w~th nozzles arranged to d~scharge directly onto the f~re

4 1 2* Uses Local appllcatlon systems shall be used for the extlngulshment of flres in flammable or combustlble llqulds gases and shallow sollds such as palnt deposits where the hazard is not enclosed or where the enclosure does not conform to the requirements for total floodlng Appllcatlon of dry chemical shall be from nozzles mounted on the tank side or overhead

4 1 3 General Requlrements Local appllcatlon systems shall be designed installed tested and malnta~ned mn accordance w~th the appllcable requlrements in Chapter 2 and wlth the addlt~onal requlrements set forth in th~s chapter

4 2 Hazard Speclflcatlons

4 2 I Extent of Hazard The hazard shall be So isolated from other hazards or combustlbles that f l re w111 not spread outside the protected area The entlre hazard shall be protected The hazard shall ~nclude all areas that are or may become coated by combustlble or flammable llqulds or shallow solld coatlngs such as areas subject to splllage leakage drlpplng splashing or condensation and all assoclated materials or equipment such as freshly coated stock dralnboards hoods ducts etc that m~ght extend f l re outside or lead f~re into the protected area

Exceptlon Protection of the entlre hazard may requlre the combined use of local appllcatlon and total floodlng systems such as ~n a restaurant kltchen where surface cooklng appllances can be protected by a local appl~catlon system and the space above the grease f11ters In the hood can be protected by a comblnatlon local appllcatlon total floodlng system See Chapter 6

4-2 2 Locatlon The deslgn of the system shall conslder the locatlon of the hazard whlch may be indoors partly sheltered or completely outdoors so as to prowde a dlscharge that w111 not be affected by wlnds or other stray a~r currents

4 3 Dry Chemlcal Requlrements and Dlstrlbutlon

4 3 1 General The following factors shall be considered in the deslgn of local appllcatlon systems

(a) Mlnlmum quantlty of dry chemcal

(b) M1nlmum flow rate

(c) Nozzle dlstrlbutlon patterns

73

NFPA 17 (d) Nozzle placement l~mltat~ons with respect to flammable

llquld surfaces

(el Posslble obstruction to nozzle dlstr~butlon pattern

Exception In the case of the pre engineered systems the rate of flow need not be considered since ~t is governed by the pipe and nozzle 11mtat~ons verlfled by a testing laboratory (see Chapter 6 and A-3-3 I)

4 3 2 Draft Condst~ons The quantity of dry chemical the dry chemical flow rate and the number of nozzles shall be suff~clent to extlngulsh f~res under the most severe wlnd or the most severe draft cond~tlons expected in the hazard area

4-3 2 1 The maximum allowable draft condltlon shall be that specified by a testing laboratory

4-3 3 Nozzle Placement The nozzles shall be placed so as to provlde an extlngulshlng concentration of dry chemlcal over the entire hazard area durmg dlscharge

4 3 3 1 The nozzles shall be placed about (tankslde) and/or above (overhead) the flammable l~qu~d surface wlthm the llm~ts of the l~st}ng ~n order to prevent splashlng durlng dlscharge

4 3 4 Coated Surfaces Although i t ~s recognized that f~res on coated surfaces are less severe than flres ~n deep layer flammable liquids such areas shall be treated as ~f they were deep layer flammable l~quld areas because no dlstlnctlon has been made in this standard

4-3 5 Duration of Discharge The mlnlmum effective discharge time shall be determined by the required m~nlmum quantlty of dry chemical and the mlnlmum appllcatlon rate

Exception In the case of pre englneered systems these factors need not be considered since they are governed by the p~plng and nozzle limitations qathered by a testing laboratory See Chapter 6

4-3 5 i * In the case of engineered systems the mln~mum discharge t~me shall be increased to compensate for any hazard condition that would require a longer discharge period to assure complete extinguishment

Exception Hot saponlflable fats do not require an extended discharge perlod when sodium bicarbonate based dry chemical is the ext~ngulshlng agent

4 4 Special Considerations Where systems protect hazards which are normally heated such as deep fat fryers char-broilers upright bPoilers griddles and ranges in kltchens or wax tanks the power or fuel supply to heaters shall be shut off automat~cally upon actuation of the extlngulshlng systems

All shutdown dewces shall be consldered integral parts of the system and shall function wlth the system operation Thls equipment shall be of the type that requires manual resetting prior to fuel or power being restored

Chapter 5 Hand Hose Line Systems

5 1 General Informatlon

5 1 1 Defln~t~on Hand hose llne systems means a hose and nozzle assembly connected by fixed plplng or d~rectly to a supply of dry chemical

5 1 2 Supply A separate dry chemcal supply may be provided for hand hose llne use or dry chemical may be p~ped from a central storage unit which may be supplying several hose llnes or fixed manually or automatically operated systems (see 2-3 2 and 2 3 3)

5 1 3 Uses Hand hose llne systems shall be acceptable to supplement fixed nozzle f i re protection systems or to supplement portable f i re extinguishers for the protection of speclflc hazards for which dry chemcal is a suitable extlngulsh~ng agent These systems shall not be used as a substltute for dry chemlcal f~re extlngulshng systems equipped w~th f}xed nozzles except where the hazard cannot be adequately or economlcally provided with fixed nozzle protect}on The decls~on as to whether hose lines are appl~oable to the particular hazard shall rest wlth the authority having 3ur~sd~ctlon

5-i 4 General Requirements Hand hose l~ne systems shall be ~nstalled and ma~ntalned ~n accordance with the applicable prows~ons of Chapters 2 3 and 4 except as outlined below

5-2 Hazard Speclflcatlons Hand hose l~ne systems shall be considered suitable for combattlng flres in all hazards covered under Chapter 2 except those which are inaccess~ble and beyond the scope of manual f l re f~ght~ng

5-3 Locatlon and Spacmg

5 3 1 Location Hand hose l~ne stations shall be placed so that they are easlly accessible and have hos~ lines long enough to reach the most d~stant hazard that they are expected to protect In general they shall be located so that the~ are not exposed to the hazard

NFPA 17

5 3 2 Spaclng I f multiple hose stations are used they shall be spaced so that any area wlthln the hazard may~be covered by one or more hose Imes /~

5-3 3 Actuatlon Manual actuatlon of the dry chemical system shall be possible at each hose llne statlon

5-4 Dry Chemlcal Requirements

5 4 1" Rate and Duratlon of Discharge The rate and duration of dlscharge and consequently the amount of dry chemlcal shall be determlned by the type and potential size of the hazard A hand hose llne shall have a suff~clent~quantlty of dry chemical to permlt its effective use for a mlnlmum of 30 seconds The mlnlmum flow rate shall also be sufflclent to prevent surging and interrupted discharge These values for mlnlmum flow rate shall be conf~rmed by a testing laboratory

5 4 2 Provision for Use by Inexperlenced Personnel The posslb111ty of these hose lines being used by inexperienced personnel shall be considered and adequate prowslon made so that there wil l be a sufflclent supply of dry chemical to enable them to effect extlngulshment of f lres in the hazards that they are l lkely to encounter

5 4 3 Simultaneous Use of Hose Lines Where simultaneous use of two or more hose Imes is possible a sufflclent quantity of dry chemical shall be avallable to supply the maximum number of nozzles that are l ikely to be used at any one tlme for at least 30 seconds and at the approprlate flow rates

5-5 Equipment Speclflcatlons

5-5 I Hose Hose lines on systems shall incorporate hose listed for this use Normally identlfylng marklng on the hose w111 ~ndlcate the acceptability of the hose for th~s purpose

5 5 2 Nozzle Assemblies Nozzles shall be so deslgned that they can be handled by one man and shall incorporate a qulck-openlng shutoff arrangement to control the flow of dry chemical

5 5 3 Hose L~ne Storage The hose shall be co~led on a hose reel or rack so that i t wil l be ready for irm~edlate use wlthout the necessity of coupl~ng and may be uncoiled with a mlnlmum of delay I f ~nstalled outdoors i t shall be protected agalnst the weather

5 5 4* Operation of Hose Lines

5 5 4 1 The pressurizing valve shall remain ~n the open pos~t~on durlng the entire f~re flght~ng operation

5 5 4 2 The hose lines shall be cleared of dry chemical ~mmed~ately after use

5 6 Tralnlng All personnel who are l~kely to use th~s equipment shall be kept properly trained ~n its operation and ~n the f l re flght~ng techniques appl~cable to thls equipment

Chapter 6 Pre Engineered Systems

6 1 General Informatlon

6 1 1 Pre englneered systems consist of components deslgned to be installed according to pretested llmltatlons as listed

6 1 2 Uses Pre-englneered systems shall be installed to protect hazards wlthln the llmltatlons which have been establlshed by the l lstlng organlzatlon

6 i 3 General Requirements Pre eng}neered systems may have speclal llmltatlons flow rates and methods of appllcatlon whlch dif fer from the requlrements speclfled in Chapters 1-5 of this standard Therefore these systems shall be installed in accordance with the manufacturer s installatlon manual whlch Is referenced as part of the l lst lng Only system components referenced in the manufacturer s mstallatlon manual shall be used

6 1 4 Inspectlon All pre-englneered dry chemcal systems shall be visually inspected monthly

6-2 Types of Systems

6-2 1 Pre englneered dry chemcal systems may be of the following types

I (a) Local apphcatlon

(b) Total flooding

(c) Hand hose llne

(d) Comblnatlon of local appllcatlon and total flooding

6-3 Restaurant Hood Duct and Cooking Appliance Systems

7 4 ,

NFFA 17 6 3 1 All cooking appllances protected by a pre-englneered automatic dry chemical extlngulshlng system shall be provided w~th an automatic means to ensure the shutdown of fuel or power to the protected appllances upon system actuation (see 4-4)

NOTE Exhaust fans do not need to be shut down or dampers closed upon system actuation s~nce the systems have been tested under both zero and high velocity flow conditions

6-3 2 Systems protecting two or more common hoods or plenums o~ both shall be installed to ensure the simultaneous operatlon of all systems protecting the hoods plenums or both or associated cooking appliances located below the hoods

6-3 3 Systems protecting exhaust ducts which are fed from two or more separate hazards shall be designed for simultaneous operation of all systems protectlng the hoods ducts and associated cooklng appliances

6-3 4 Eutect~c a11oy type fuslble links shall be replaced at least annually (see 2 10 1 9)

6-3 5 A fuslble llnk or heat detector sh~11 be prowded above each cooklng appllance or group of appliances protected by a slngle nozzle

Exceptlon A fuslble llnk or heat detector is not required above cooklng apphances located dlrectly below the exhaust duct provlded a fuslble llnk or h~at detector is installed at or wlthln 12 in (305 mm) of the entrance to the duct

6 3 6 All discharge nozzles shall be f i t ted wlth protectlve caps

6 3 7 The owner of the restaurant shall be provided w~th a copy of the manufacturer s installae~on and maintenance or owner s manual which describes system operatlon requlred malntenance and recharging

6-4 Vehicle Fuellng Serwce Station Systems

6-4 1 All vehicle fueling areas protected by two or more systems shall be connected for s~multaneous operation

6-4 2 Protected area shall Include the area w~thln the arc scribed by the nozzle end of the hose on each vehicle fuel dispenser

CAUTIONARY NOTE The manufacturer of the system shall be consulted to determine the need for addltlonal coverage under adverse w~nd conditions

6-4 3 Suitable means shall be provided to contam~the fuel spil l w~th~n the protected area (See NFPA 30 Flammable & Combustlble Liquids Code )

6-4 4 Equipment shall be provided to s~multaneously shut down al l vehicle fuel dispensers upon system actuation In the event of a system discharge the hazard being protected shall not be returned to serwce un t i l such time as the system is recharged~nd operational

6-4 5 Automatic detection and actuation of the extinguishing system shall be provided The manufacturer s installation manual shall be consulted regarding the type and location of the detectors

6 4 6 A remote manual system actuator shall be provided in a conspicuous and accessible 1ocat~on away from the vehicle fuel dispensers and protected area

!

6-4 7 All manual actuators shall be provlded w~th operating instructions These instructions may include the use of pictographs and ~hall have letterlng at least I /4 in (6 35 mm) in height (See 2-6 3 4 )

6-4 8 A11 d~scharge nozzles shall be provided with caps or other suitable devices to prevent the entrance of moisture or other foreign materials ~nto the piping

6-4 g All discharge nozzles shall be located so as to m~nlm~ze the l~kellhood of damage or misalignment and wlth~n the limitations and constraints of the manufacturer s installation manual

6-5 Systems for the Protection of Mobile Equipment

6-5 1 Only pre englneered dry chemical systems which have been listed for such use shall be installed on mobile equipment For information on mobile surface m~nlng equipment see NFPA 121

6-5 2 Compartments or areas which could be subject to f i re shall be protected ~n accordance w~th the manufacturer s installation manual

6-5 3 Each protected compartment or area shall be provided w~th a - listed f~re detection device specified in the manufacturer s

installation manual to automat~cally actuate the extinguishing system

Exception Mechanical operation only may be prowded i f acceptable to the authorlty hawng jurisdiction

NFPA 17

6-5 4 Only the flexible hose and hose f l t t ings specified in the manufacturer s installation manual shall be used

6-5 5 All dlscharge nozzles shall be provided with caps or other suitable dewce to prevent the entrance of moisture or foreign materlals into the piping

6-5 6 All dlscharge nozzles shall be located to mlnlmlze the llkellhood of damage or misalignment and wlthln the 11mltations and constraints of the manufacturer s installation manual

6-5 7 Eutectlc alloy type fusible hnks used on mobile equipment shall be replaced at least annually (See 2-10 1 9 )

6 5 8 Locatlon of pressure contalners and manual actuator stations shall be appropriate to each appllcation protected against physlcal damage and accesslble Consideration shall be glven to multlple locations

6-5 9 At least one easlly accesslble manual system actuator shall be prowded for use by the equipment operator

6 5 10 An additional manual system actuator shall be located so that i t is in the path of egress and operable from ground level

6 5 11 I f the system is provided with a discharge delay device both audible and wsual alarms shall be prowded to warn of the impend~ng system discharge

6 5 12 In the event of system discharge the vehicle belng protected shall not be returned to service until such tlme as the system is recharged and operational

6-6 Hand Hose Line Systems f

6-6 1 Pre-englneered dry chemical hand hosellne systems may be prowded wlth turrets skld mounted hose reels remote hose reels or combinations of the above

( 6-6 2 The length and size of piping of hose and type of nozzles shall be wlthln the llmltatlons stated in the manufacturer s installation manual

6-6 3 Differences in elevation between the dry chemlcal storage tank and each turret or hose reel shall be within the limitations of the manufacturer s installation manual

J 6-6 4 I f multiple cy)inders are used to pressurlze the dry chemical powder agent containers each cylinder shall be prowded with a pressure gauge and manual means of operation

Exception Slave cylinders without manual actuators are permitted i f at least two master cylinders with manual actuators are prowded

6-6 5 Each turret and hose reel shall be provided with a manual actuator The system shall be designed so that only one manual actuator need be operated to place the system in operable condition

Exceptlon Only one manual actuator need to be provided for self contained skld-mounted systems

6-6 6 Each turret and hose reel shall be provided with a shutoff or flow control valve

6 6 7 An integral method shall be provided to blow out all system piping and hose reels after any use

6-6 8 Turret nozzles shall be provided with caps or other sultable dewces to prevent moisture or foreign materials from enterlng the turret or piping

Chapter 7 Mandatory Referenced Publications

7 1 This chapter l ists publications referenced wlthln this document whlch in whole or in part are part of the requirements of this document

7 1 1 NFPA Publicatlons The followlng publlcatlons are avallable from the National Fire Protectlon AsSoclatlon Batterymarch Park Quincy MA 02269

NFPA 70-1983 NATIONAL ELECTRICAL CODE

NFPA 71 1982 Central Statlon Signaling Systems

NFPA 72A 1979 Local Protective Signaling Systems

NFPA 72B-1979 Auxiliary Protective Signaling Systems

NFPA 72C-1982 Remote Statlon Protective Signallng Systems

NFPA 72D-1979 Proprietary Protective Signaling Systems

7-1 2 Other Publications

ASTM E380-1976 Standard for Metric P~actlce American Society for Testing and Materials 1916 Race Street Philadelphia PA 19103

75

NFPA 17

Appendlx A

Thls Appendix is not a pa~t of the requirements of thls NFPA standard but ~s ~ncluded for informat~on purposes only

A 1-1 Scope The dry chemcal systems described in th~s standard are designed to discharge dry chemlcal from f~xed nozzles and plp~ng or from hos~ llnes by means of an expellant gas The Intent of the standard ~s to present the design conslderatmns~ppllcable to these systems

Because the flow of dry chemcal (sol}d particles suspended ~n a gaseous medium) does not follow general hydraulic theories most of the flow pr~nclples have been determined experlmentally The dry chemicals produced by various manufacturers are usually not ~dentlcal ~n all character~stlcs and each manufacturer designs equipment for use wlth a specific dry chemcal Therefore system deslgn prlnc~ples applicable to the products of one manufacturer are not applicable to the products of another manufacturer As a result i t IS not practlcal to include system deslgn details as a part of th~s standard

I t ~s now generally accepted that the flame extmgu~shlng propertles of dry chemlcals are due to the ~nteractlon of the particles to stop the chain reactlon that takes place in flame combustlon Dry chemicals vary in thelr flame ext~ngu~shmg effectlveness Multlpurpose dry chemical owes its effectlveness in ext~ngulshlng f~res in ordlnary combustibles such as wood and paper to the formatlon of a glow-retardlng coating over the combustlble materlal For addlt~onal ~nformatlon on dry chemcals and their extlngu~shlng characterlst~cs see A-2 1

A 2 1 Agent Characteristics A dry chemlcal extlngu~sh~ng agent ~s a f~nely dlwded powdered materlal that has been specially treated to be water repellent and capable of belng fluld~zed and free flowing so that ~t may be d~scharged through hose llnes and p}p~ng when under expellent gas pressure Dry chemcals currently ~n use may be described brief ly as follows

1 Sodium Bicarbonate (NaHC03-) Based Dry Chemlcal

Th~s agent consists prlmarlly of sodlum blcarbonate and is suitable for use on all types of flammable llquld and gas f~res (Class B) and also for f lres ~nvolvlng energized electrlcal equlpment (Class C)

i Its effect on f~res ~n common cooklng o~Is and fats is hart]cularly good as ~n comblnatlon w~th these materials the sodium b~carbonate-based agent reacts to form a type of soap (saponlflcat~on) whlch floats on the liquid surface such as in deep fat fryers and effectively prevents re~gnlt~on of the grease

Sodlum b~carbonate based dry chemical is not generally recommended for the extinguishment of f ires in ordinary combustibles (Class A) although ~t may have a transitory effect ~n ext]ngulshlng surface flamng of such materials

2 Dry Chemcals Based on the Salts of Potass}um

Commercially available agents are essentially potassium blcarbonate (KHCO 3) potassium chlorlde (KCL) and urea based potasslum b~carbonate (KC2N2H303) All three agents are sultable for use on all types of flammable llquld and gas f~res (Class B) and also for f ires ~nvolvlng energized electrlcal equipment (Class C)

I t ~s generally recognized that salts of potassium are more effectlve in terms of chemical extinguishment mechanisms than sod}um salts ~n extlngu~shlng Class B type f~res except those in deep fat fryers and other cooking equipment

Dry chemicals based on the salts of potassium are not generally recommended for the ext~ngulshment of flres ]n ordinary combustibles (Class A) although they may have a transitory effect ~n ext~ngulsh~ng surface flamlng of such materials

3 Multlpurpose Dry Chemcals I

Th~s agent has as ~ts base monoammonlum phosphate (NH4H2P04) and ~s s~m~lar in its effect on Class B and Class C flr~s to the other dry chemicals However i t does not possess a sapon~flcat~on characteristic and should therefore not be used on deep fat fryers Unlike the other dry chemcals i t does have a conslderable ext]ngu~shlng effect on Class A materials The agent when heated decomposes to form a molten residue which w~ll adhere to heated surfaces On combustible solld surfaces (Class A) this characterlstlc excludes the oxygen necessary for propagatlon of the f l re

4 Foam-Compatible Dry Chemcals

When or where foam dry chemical systems are used or proposed for the protection of a hazard the manufacturer should be consulted as to the compat~bll~ty of the agents

t

76

NFPA 17

Extlngulshlng Mechanlsms The detalled mechanlsms by whlch dry chemlcal agents extlngulsh f lres have not been completely determlned However I t is generally accepted that the prlmary ext~ngulshlng mechanlsms include lnterruptlon of the Chaln reactlon sequence by chemcal reactions reductlon of llquld fuel evaporatlon rates by reductlon In flame radlatlon at the llquld surface and inert~ng effects due to reduction of oxygen concentratlon wlthln the active f i re zone Secondary extlngulsh~ng mechanisms may include heat absorptlon effects (partlcularly at hlgh dry chemcal concentratlons) ~ addltlonal coollng effects due to the formatlon of water vapor by the pyrolysls processes addltlonal Inertlng effects due to the formation of carbon dloxlde by the pyrolysls of the dry chemcal and f l re retardant effects due t~ surface coatings

The effectlveness of the chemcal reactlon mechanlsms dlffers w}th the currently used dry chemlcal agents and is belleved to be the prlmary reason for the dlfferences in overall effectlveness of the dlfferent agents at cr l t lcal extlngulshlng flow rates The physlcal mechanlsms such as reductlon of the flame feedback radiation and reductlon of oxygen concentrations are s~gnlflcantly mfluenced by dry chemcaI concentratlons ~n the flame zone as well as the dry chemcal agent physlcal properties The more important extlngulsh~ng mechanlsms are dlscussed In greater detall in the following paragraph

The flame chaln reactlon sequE ce Is a detailed set of chemcal reactions in an oxidative combustlon process The rates at which the various reactlons occur determne the extent of pyrolysls The reactions are best 111ustrated 1~terms of a slmple hydrocarbon such as Tethane CH 4 where the probable reactions are as follows

I

2CH 4 + 202 2CH 3 + OH + 30 + H Chaln Inlt latlon CH3 + Op~ H2CO + OH 202 + 2H 20H + 20 CH4 + OH CH~ + ~0 H2CO + 0 HCu + v. Chaln Inlt lat lon HCO H + CO CO + OH CO 2 + H HOH 2H20 + 0

f

CO + 0 COp CO + 20H ~02 + H20 Chaln Inlt latlon

The basic scheme involves in~t~at~on of the chaln reaction ~n thls case the generation of CH~ OH 0 and H radlcals These radlcals react wlth fuel materials and oxygen resulting ~n the generation of specles whlch ~n turn react to produce more radlcals In thls way the chain reactlon propagates i tse l f Normal termnatmn of the chain reaction occurs when the rad}cals necessary to propagate the chain reaction are destroyed through recomblnat~on or by chemlcal reactlon

I t is w~dely accepted that two baslc mechanisms are involved ~n the chem}cal ext~ngulsh~ng actlon of a dry chemlcal and that thelr contribution to the overall extinguishing effectiveness dlffers with each type of dry chemical agent However both mechanisms are based upon the abl l l ty of the agent to cause termnat~on ~n the chain reaction of the fuel oxld~zer combination

One chemcal mechanlsm involves the increase in the ext~ngulsh~ng effectiveness that Is observed wlth decreasing medlan particle s~ze This Is most generally d~scussed ~n terms of the total surface area of all the partlcles or speclflC surface area rather than median particle slzo In general the hlgher the specific surface area the more effectlve the agent w~th~n the constraints imposed by hardware conslderatlons The argument advanced ~s that decreaslng the medlan particle slze (increaslng the specific surface area) affords more active surface for radicals generated ~n the flame to recomblne on thus accelerating the termlnatlon of the chaln reaction occurring w~thln the flame The other chemical mechanism involves the formation of chemical specles capable of reactmg w~th chaln propagating radicals 2 I t ~s belleved that f~nely dlwded salts containing Na or K because of a hlgh surface area exhlblt good heat transfer characterlstlcs resulting in vapor~zat}on of the h~ghly reactive metal or metal hydroxlde which can efflc~ently scavenge H or OH radicals ~n the chain reaction propagatlon ~n the flame resulting In chaln termination In general the chemical ext}ngulshlng reactions become more energetlcally favorable as the atomlc weight of the metal ion increases w~thln the metals of Group IA of the Perlodlc Table

The level of effectiveness of agents based upon monoammonlum phosphate NH4H2PO 4 which has been found to be sl ightly less than that of agents based on potassium salts cannot readily be explalned by the foregoing theories The reaction of thls material w~th flame radicals ~s energetically less probable I t is more l ikely that a complex reaction sequence involving a complex form of the anion (H2P04)- occurs Th~s mater~al can undergo extensive endotfiermc (energy absorblng) reactlons whlch tend to cool the flame and affect the chain reaction sequence by remowng energy from the system An increase in effectlveness wlth Increas~ng specific surface ~s also observed with th~s material

1Westenburg A A and Fr~strom R M J Phys Chem 65 591 (1961)

2Fr~edman R and Levy J B Combustmn and Flame 7 195 (1963)

NFPA 17 / In add~tlon to the ~nterruptlon of the flame process by chemical

chain breaklng and formation of chemical compounds /d ry chemicals also u t i l i z e mechanical d~sturbance to a~d In extlngu~sh~ng flames Th~s character~stlc can be readi ly observed in Class B f i res when the dry chemical par t lc les come between the fuel source and the burning vapors A noticeable heat shielding e f fec t is also apparent slnce the dry chemical par t ic les prevent some rerad~at~on of the flames to the fuel source thus reducmg the rate at which combustible vapors are produced The softening and adheslve chara~ter lst lcs of monoammonlum phosphate dry chemlcal when heated serve as an added mechanlcal d~sturbance to the Class A type f~re by coating burning materials w~th an imperwous layer

A 2 2 1 Gas f l r es should normally not be ext~ngulshed unless the source of burning gas can be shut o f f because an explosive mlxture may be formed w~th a l r whlch ~f ~gn~ted may cause greater damage than the or~glnal f~re

Factors that determine i f the gas f~re should be extinguished prlor to shuttlng off the gas supply are

(a) Access~b~llty of gas shutoff valves Where water hose streams are not available i t may be necessary to extlngu~sh the f~re ~n(order to reach the shutoff valves

(b) The prox~mity of other flammable or combustible materlals I f ~gnltlon of these materials could result ~n a more hazardous condition the f l re may have to be ext~ngulshed prior to gas shutoff

(c) Personnel rescue Dry chemical should be appl~ed at flow rates and d~scharge patterns that w~ll be effective Gas l~ne flange l~ne rupture or ~mplnglng fires may require special flow rates and d~scharge patterns

A-2-2 2 3 Monoammonlum phosphate and potassium chloride are sl ight ly acld~c and ~n the presence of moisture can corrode metals such as steel cast Iron and aluminum

Potasslum blcarbonate sodium bicarbonate and urea-based " potassium bicarbonate are sl~ghtly basic and in the presence of

molsture can corrode metals such as aluminum alumlnum brass aluminum bronze and tltan~um

Such corrosion w~ll vary from a dull or tarnished flnish to mild surface corroslon Corroslon need not be of concern when accompanied by prompt cleanup For the most part these dry chemical agents can be readily cleaned up by w~plng vacuuming or washing the exposed materials Monoammon~um phosphate-based agent wil l require some scraping and washlng i f exposed surfaces were hot when the agent was applied

A 2 4 Hazards to Personnel Dry chemical f l re ext~ngulsh~ng agents are considered nontoxic from a physiological point of wew However as w~th any f lnely d~vided material they may produce mild ~rrltat~on effects espec~ally when used ~n an enclosed area In general these effects are neither serious nor permanent

For more speclfic guldance on indlvldual dry chemical extlngulsh~ng agent components and thelr hazards to personnel (TLV values) consult the dry chemlcal manufacturer

A-2 6 5 I f only local alarms are provided consideration should be given to transm~ttlng th~s alarm to a constantly attended location

A 2-7 3 Reserve Supply A fu l l y cha~ged reserve unit permanently connected to the system ~s desirable and may be required by the authority hawng jurisdiction

A 2 9 1 The plp~ng for a dry chemical system embodies d~stlnct~ve features necessitated by the characterlst~cs of the agent The use of f lexible piping or hoses ~n a dry chemcal system introduces a number of thlngs to be considered that do not normally affect r~gld piping The most ~mportant of these ~s the nature of any changes of dlrect~on The m~n~mum radlus of curvature for any flexible hose to be used in a dry chemcal system ~s usually shown ~n the l~st~ng information for a partlcular system Other areas of concern that are evaluated ~n the test for l~stlng are resistance to the effects of vlbrat~on flexure tension torsion temperature flame compression and bendlng I t is also necessary for the hose to have the strength to contain the dry chemical during discharge and be\ made of materlals that will be resistant to atm~spherlc corrosion

A 2-9 2 Dry Chemical Piplng ~The following material enumerates some of the necessary conslderatlons that must be incorporated when p~p~ng a mixture of dry chemical and expellant gas The flow of the mixture of dry chemical and gas does not s t r i c t l y follow general hydraulic principles because i t is two-phase flow The flow characterlstlcs are dependent upon the composition and physical characteristics of the type and make of the dry chemical being used the type of expellant gas being used and the design of the equipment being used \

NFPA 17

Pre-englneered systems do not need calculations for flow rate pressure drop and nozzle pressure since they have been tested for f l r e extinguishment wlth mlnlmum and maximum plplng l lml ta t lons includlng length of plpe and number and type of elbows and minimum and maxlmum temperature I iml tat lons These l imi ta t ions have been ver l f l ed by testing laboratorles and are published in the manufacturer s ins ta l la t lon manual

q Englneered systems are calculated to show that the proper f low rate and no~zle pressure are obtained w~th the pressure drop occurrlng in the plplng layout The necessary charts graphs and nozzle pattern Informatlon must be obtalned from the equipment manufacturer and are verlfled by testlng laboratorles

The plpe f i t t ings valves et~ used to distribute the dry chemical should be as speclfled in 2-8 1 and 2-8 2 of thls standard

Changes in direction of flow causes separation of expellant gas and dry chemical To provide proper dlstrlbutlon of dry chemical upon sp~ittlng the stream~ speclal attentlon must be glven to the method in which an approach ~s made to a tee after a change ~n dlrectlon Certaln acceptable methods are shown in Figures A-2-8 2(a) and A 2 8 2(b) Other methods and equlpment may be recognlzed by a testlng ~aboratory in its listings

A 2 10 1 Regular servlce contracts w~th the manufacturer or hls authorized install~ng or maintenance company are recommended

A 3-3 1 The llmltlng spec~flcatlons for a dry ch~mlcal system are a functlon of the flow characterlst~cs of the partlcular dry chemlcal and equlpment used by the manufacturer of the system Therefore i t is not posslble to specify in thls standard the exact values for the quantlty requlred rate of flow requlred or nozzle dlstrlbutlon The above cons~deratlonsrare carried In thls standard to point out the important features which should be made available to the purchaser Inspector or other authorities charged wlth the examlnatlon and evaluatlon of thls system These data should be establlshed by investlgat~on and tests conflrmed by a testing laboratory

A-4 1 2 Examples of hazards that may be successfully protected by local appllcatlon systems include d~p tanks quenching o11 tanks spray booths o11-f~lled electrical transformers vapor vents deep fat fryers etc

A 4 3 5 1 Sodium b~carbunate ~s decomposed by heat to form carbon dlox~de water vapor and sodium carbonate The latter reacts wlth saponlflable fats to form soap and s~multaneously releases additional carbon dioxide The resultlng soap foam forms a lastlng blanket over the hot fat and prevents both flame ]gnlt~on and auto~gnlt~on

NOT L E ~ T H A N ~ TER~

f

Figure A-2-8 2(a) ll lustratlons of acceptable means of plplng into a tee in a dry chemlcal system

77

NFPA 17

VENTURI ASSEMBLY

T Y P I C A L ! A P P L I C A T I O N OF

V E N T U R | A S S E M B L Y

L E S S T H A N 2 0 P I P E D I A M E T E R S

Figure A 2-8 2(b)

A-5 4 1 An unusually low flow rate w111 cause the dry chemlcal to separate from the expellant gas while w~th~n the p~pe and/or hose resulting in uneven flow from the nozzle

A-5-5 4 Operation of hand hose hne systems depends on manual actuation and manlpulatlon of a dlscharge nozzle Speed and slmpl}clty of operation are essential

Appendlx B Informatory Referenced Publlcatlons

B-I Thls portion of the Appendlx l lsts pubhcatlons referenced withln thls NFPA standard

B-1 1 NFPA Publlcatlons The followlng publlcat~ons are available from the Natlonal Fire Protectlon Association Batterymarch Park Qulncy MA 02269

NFPA 10-1981 Standard for Portable Fire Extlngulshers

NFPA 30-1981 Flammable Combustlble L1qulds Code

NFPA 72E 1982 Standard for Automatlc Fire Detectors

NFPA 96-1984 Standard for the Installatlon of Equlpment for the Removal of Smoke and Grease-Laden Vapors from Commerclal Cooking Equlpment

NFPA 121-1981 Fire Protectlon for Moblle Surface Mining Equlpment

J

78 i