Amca 99

7/27/2019 Amca 99

1/85

The International Authority on Air System Components

AMCA Publication 99

Standards Handbook

7/27/2019 Amca 99

2/85

7/27/2019 Amca 99

3/85

AMCA 99 Standards Handbook

COPYRIGHT 2003 by Air Movement and Control Association International, Inc.

All rights reserved. Reproduction or translation of any part of this work beyond that permitted by Sections

107 and 108 of the 1976 United States Copyright Act without the permission of the copyright owner is

unlawful. Requests for permission or further information should be addressed to the Executive Director,

Air Movement and Control Association International, Inc.

7/27/2019 Amca 99

4/85

AMCA 99 Standards Handbook

AMCA 99

STANDARDS HANDBOOK

CONTENTS

99-0021-01 The Fan Laws

99-0066-01 The AMCA Vocabulary: Definitions

99-0068-03 The AMCA Vocabulary: Product Definitions

99-0070-01 The AMCA Vocabulary: Symbols

99-0098-00 Basic Series of Preferred Numbers

99-0100-76 Metric Units and Conversion Factors99-0200-00 Charts & Tables

99-0401-86 Classification for Spark Resistant Construction

99-1401-66 Operating Limits for Central Station Units

99-2404-03 Drive Arrangements for Centrifugal Fans

99-2405-03 Inlet Box Positions for Centrifugal Fans

99-2406-03 Designation for Rotation and Discharge of Centrifugal Fans

99-2407-03 Motor Positions for Belt or Chain Drive Centrifugal Fans

99-2408-69 Operating Limits for Centrifugal Fans

99-2410-03 Drive Arrangements for Tubular Centrifugal Fans

99-2412-03 Impeller Diameters & Outlet Areas for Centrifugal Fans

99-2413-03 Impeller Diameters & Outlet Areas for Industrial Centrifugal Fans

99-2414-03 Impeller Diameters & Outlet Areas for Tubular Centrifugal Fans

99-3001-03 Dimensions for Axial Fans

99-3404-03 Drive Arrangements for Axial Fans

7/27/2019 Amca 99

5/85

Purpose of AMCA Standards

AMCA Standards are adopted in the public interest. They are intended to eliminatemisunderstanding between the manufacturer and the purchaser and to assist in selecting,specifying, and obtaining the proper product for the particular need.

Existence of an AMCA Standard does not in any respect preclude any member or non-memberfrom manufacturing or selling products not conforming to the standard.

Approval of Standards

Proposed standards are reviewed by the appropriate Standards Committees and by the Board ofDirectors before submittal to the membership for approval. An affirmation vote of two-thirds of themembers affected is required for adoption or revision.

Review of Standards

AMCA Standards are regularly reviewed, but may also be reviewed at any time at the request ofthe membership or by direction of the Board of Directors.

7/27/2019 Amca 99

6/85

AMCA PUBLICATION 99

STANDARDS HANDBOOK

CONTENTS

99-0021-01 The Fan Laws

99-0066-01 The AMCA Vocabulary: Definitions

99-0068-03 The AMCA Vocabulary: Product Definitions

99-0070-01 The AMCA Vocabulary: Symbols

99-0098-00 Basic Series of Preferred Numbers

99-0100-76 Metric Units and Conversion Factors

99-0200-00 Charts & Tables

99-0401-86 Classification for Spark Resistant Construction

99-1401-66 Operating Limits for Central Station Units

99-2404-03 Drive Arrangements for Centrifugal Fans

99-2405-03 Inlet Box Positions for Centrifugal Fans

99-2406-03 Designation for Rotation and Discharge of Centrifugal Fans

99-2407-03 Motor Positions for Belt or Chain Drive Centrifugal Fans

99-2408-69 Operating Limits for Centrifugal Fans

99-2410-03 Drive Arrangements for Tubular Centrifugal Fans

99-2412-03 Impeller Diameters & Outlet Areas for Centrifugal Fans

99-2413-03 Impeller Diameters & Outlet Areas for Industrial Centrifugal Fans

99-2414-03 Impeller Diameters & Outlet Areas for Tubular Centrifugal Fans

99-3001-03 Dimensions for Axial Fans

99-3404-03 Drive Arrangements for Axial Fans

7/27/2019 Amca 99

7/85

THE FAN LAWS

Fan impellers differ from one another in many respects, even among those of the same type. One

characteristic that all share is that each individual impeller design can be uniquely related to the overall

diameter of the impeller. Because of this unique relationship, all impellers that share the same geometric

design but differ only in size are said to have similarity. Fan casings share in this unique relationship, with the

casing being optimized with respect to an impeller design so that aerodynamic performance goals are

achieved. A fan design, then, is a geometrically unique combination of fan impeller and fan casing. All sizes

of fans produced according to this unique geometry have similarity based on their respective diameters.

Similarity is useful in that it enables the prediction of aerodynamic performance: given the performance of a

fan of a given diameter at a certain rotational speed and a certain air density, the performance of that same

unique geometry at another impeller diameter, or rotational speed or air density can be determined.

Note that the variables that affect a fan's aerodynamic performance are: impeller diameter, rotational speedand air density. Since these variables are expressed as ratios, they are dimensionless and are independentof the system of units used, as long as the units are used consistently for each ratio.

The mathematical statements which describe the effects of these factors on aerodynamic performance for

any known performance point are known collectively as the FAN LAWS.

FAN LAWS FOR COMPRESSIBLE FLOW

As with all laws, some similarity requirements must be met if the FAN LAWS are to be effective:

A. DESIGN GEOMETRY

Geometric similarity must exist between any two fan sizes; i.e., dimensions must be proportional andangularity must be constant for all essential air passages of the impeller and the casing.

B. GAS DENSITY

As air moves through the fan, it is acted upon by the rotating impeller and there results a pressure rise. Witha pressure rise, one would expect that the gas undergoes compression. Compression, in turn, means achange in gas density.

The compressibility coefficient (Kp) must be calculated for the condition. The supporting formulas forKp

originate in Appendix C, ANSI/AMCA Standard 210-99.

2001 Air Movement and Control Association International, Inc.

Air Movement andControl Association

International, Inc.Arlington Heights, IL

60004-1893 U.S.A.

THE FAN LAWSBSR AMCASTANDARD99-0021-01

PAGE 1 OF 10

7/27/2019 Amca 99

8/85

C. REYNOLDS NUMBER

Reynolds number is one of many descriptors of fan performance, and further information is available in most

textbooks on fluid mechanics. For our purposes here, it is necessary to know that for a given fan design

geometry, there are many possible Reynolds numbers, and that there is a threshold value on either side of

which fluids behave differently. The similarity requirement here is that both sets of operating parameters

result in Reynolds numbers such that the effect of any difference between them is negligible. The implied

requirement is that both of the Reynolds numbers must be on the same side of the threshold value. For

additional information on Reynolds number, see Handbook of Fan Engineering, latest edition.

D. MACH NUMBER

Mach number relates to the velocity of a gas (air) as it passes into or through a fan. Similarity requires that

the Mach numbers for the two sets of parameters must be reasonably close. Just as was the case withReynolds number, there is a threshold value and a difference in performance on either side of the threshold.Since almost all fans operate well below the threshold value for Mach number, no procedure for determiningthe threshold value is given in this document.

Then for any given point on a fan performance curve, the relationship between a known performance point

and desired performance point c (converted) is given by the FAN LAWS.

THE FAN LAWS

1ST LAW:

Q

Q

D

D

N

N

K

K

c c

3

c p

pc

=

2ND LAW:

P

P

D

D

N

N

K

K

tc

t

c

2

c

2p

pc

c

=

3RD LAW:

P

P

D

D

N

N

vc c

2

c

2

c

=




60004-1893 U.S.A.


PAGE 2 OF 10

7/27/2019 Amca 99

9/85

Errata February 2005

AMCA 99-0021-01

On page 2 of 10 the last equation on the page should read:

[The denominator of the first term should have the subscript v.]

=

ccc

v

vc

N

N

D

D

P

P22

7/27/2019 Amca 99

10/85

4TH LAW:

H

H

D

D

N

N

K

K

c c

5

c

3p

pc

c

=

5TH LAW:

P P Psc tc vc =

Where Ptc and Pvc are established per the 2ND

and 3RD

FAN LAWS.

6TH LAW:

sc tc sc

tc

P

P=

Where Psc is established using the 5TH

FAN LAW and Ptc is established using the 2ND

FAN LAW.

In the above, subscript c denotes the new operating condition, and:

D = Impeller diameter

Dc = Impeller diameter, converted

N = Impeller rotational speed

Nc = Impeller rotational speed, converted

Q = Volume airflow rate

Qc = Volume airflow rate, converted

Pt = Pressure, total

Ptc = Pressure, total, converted

Pv = Pressure, velocity

Pvc= Pressure, velocity, converted

H = Power

Hc = Power, convertedPs = Pressure, static

Psc= Pressure, static, converted

sc = Efficiency, static, converted

tc = Efficiency, total, converted




60004-1893 U.S.A.


PAGE 3 OF 10

7/27/2019 Amca 99

11/85

and Kp and Kpc are determined from:

( )( )

Kln 1 x

x

z

ln 1 z p =

+

+

( )x

P

P C p

t

t1 b b

=+

( )( )

z1 C H

Q P C p

h

t1 b b

=

+

z

z

P C p

P C p

N

N

D

D 1

1c t1 b b

t1c b bc

c c

2

c

2

c

c

=+

+

K 11

1z

2 11

12

z

6pc

t c

c

c t c

c

c c

c

c2

1

= +

+

,

an approximation derived from a series expansion, sufficiently accurate for Kp >= 0.9, and fan mechanical

efficiency t is given by:

tt p

h

QP K

C H=

Note: For all fans, t=tc (for incompressible flow only)

Where:Kp = Compressibility coefficient

Kpc = Compressibility coefficient, converted

x = A coefficient of convenience in the equation

z = A coefficient of convenience in the equation

Pt1 = Total pressure at fan inletCb = Barometer constant: SI = 1 (I-P = 13.63)

Ch = Power constant: SI = 1 (I-P = 6362)

pb = Barometer pressure, Pa (in. Hg)

= Ratio of specific heats = 1.4

EXAMPLE:

The following example shows how the FAN LAWS, including compressibility, are applied in aerodynamic

performance predictions for a given fan design.




60004-1893 U.S.A.


PAGE 4 OF 10

7/27/2019 Amca 99

12/85

KNOWN PARAMETERS:

SI I-P

impeller diameter D 927 mm 36.5 inches

fan rotational speed N 1000 rpm 1000 rpm

air density 1.152 kg/m3

0.072 lbm/ft3

volume airflow rate Q 7.952 m3/s 16850 cfm

total pressure Pt 953.7 Pa 3.84 in. wg

barometric pressure pb 97.359 kPa 28.75 in. Hg

power H 9299 W 12.47 hp

ratio of specific heats 1.4 1.4

CONVERSION PARAMETERS:

SI I-P

impeller diameter Dc 1524 mm 60 inches

fan rotational speed Nc 820 rpm 820 rpm

air density c 1.2 kg/m3

0.075 lbm/ft3

volume airflow rate Qc UNKNOWN UNKNOWN

total pressure Ptc UNKNOWN UNKNOWN

power Hc UNKNOWN UNKNOWN

barometric pressure pb 101.321 kPa 29.92 in. Hg

To determine the flow rate Qc and pressure Ptc, FAN LAWS 1 and 2 must be used. The GIVEN and

CONVERTED conditions provide all the information required for the calculations except Kp and Kpc.




60004-1893 U.S.A.


PAGE 5 OF 10

7/27/2019 Amca 99

13/85

Determine Kp:

( )( )

Kln 1 x

x

z

ln 1 z P =

+

+

EXAMPLE CALCULATIONS IN SI UNITS:

( )x

P

P C P

t

t1 b b

=+

( )( )( )= + 953.70 1 97359

=953.7

97359

x 0.0097957=

( )( )z

1 C H

Q P C P

h

t1 b b

=

+

( )( )

( )( )( )=

+

1.4 1

1.4

1 9299

7.952 0 1 97359

z 0.0034317=

( )( )

Kln 1 x

x

z

ln 1 z p =

+

+

( )( )

=+

+

ln 1 0.0097957

0.0097957

0.0034317

ln 1 0.0034317

K 0.99684p =




60004-1893 U.S.A.


PAGE 6 OF 10

7/27/2019 Amca 99

14/85

tt p

h

QP KC H=

( )( )( )( )( )

=

7.952 953.7 0.99684

1 9299

t 0.813, or 81.3%=

To determine Kpc , calculate the factors in the necessary equations:

( )( )

z

z

P C p

P C p

N

N

Dc

D

c t1 b b

t1c b bc

c c2 2

= ==

( )( )

=+

+

0 1x97359

0 1x101321

1.2

1.152

820

1000

1524

927

2 2

z / z 1.81905c =

Then:

( )( ) ( )z

zz 1.81905 0.0034317 0.006242c = =

And:

( )( ) ( )( )

t c

c 1

0.813 1.4

1.4 12.8455

=

=

( ) ( )( )

K1

1 2.8455 1 0.0062422

2.8455 1 2.8455 2 0.0062426

pc 2=

+ +

Then:

K 0.994235 pc =




60004-1893 U.S.A.


PAGE 7 OF 10

7/27/2019 Amca 99

15/85

And to obtain the values for the unknowns at the converted conditions:

Q 7.952 1524927

8201000

0.996840.994235

c

3

=

= 29.05 m / s3

P 953.7 1524

927

820

1000

1.2

1.152

0.99684

0.994235tc

2 2

=

=1810.2Pa

H 9.2991524

927

820

1000

1.2

1.152

0.99684

0.994235c

5 3

=

= 64.31 kW EXAMPLE CALCULATIONS IN I-P UNITS:

( )x

P

P C p

t

t1 b b

==

( )( )=

+

3.84

0 13.63 28.75

=3.84

391.86

x 0.0097994=

( )( )z

1 C H

Q P C p

h

t1 b b

=

+

( )( )

( )( )( )=

+

1.4 1

1.4

6362 12.47

16850 0 13.63 28.75

( )=

+

0.4

1.4

79334.14

16850 0 391.86




60004-1893 U.S.A.


PAGE 8 OF 10

7/27/2019 Amca 99

16/85

( )( )( )( )

=

0.2857 79334.14

16850 391.86

( )( )( )

=

0.2857 79334.14

6602841

( )( )[ ]= 0.2857 0.0120151

z 0.0034327=

To determine Kpc, calculate the factors in the necessary equations:

Then:

( )( )

z

z

P C p

P C p

r

r

N

N

D

D

c t1 b b

t1c b bc

c c

2

c

2

=+

+

( )( )( )( )

=+

+

0 13.63 3.84

0 13.63 28.75

0.075

0.072

820

1000

60

36.5

2 2

= 1.818652

( )( )z 1.818652 0.0034327 0.006243c = =

And:

( )( )

t c

c 1

0.813 1.4

1.4 1

1.1382

0.42.8455

=

=

=

( ) ( )( )

K1

1 2.8455 10.006243

22.8455 1 2.8455 2

0.006243

6

pc 2

=

+

+

Then:

K 0.994262 pc =




60004-1893 U.S.A.


PAGE 9 OF 10

7/27/2019 Amca 99

17/85

And to obtain the values for the unknowns at the converted condition:

Q 1685060.0

36.5

820

1000

0.075

0.072

0.99684

0.99426c

3 2

=

= 61534 cfm

P 3.8460.0

36.5

820

1000

0.075

0.072

0.99684

0.99426tc

2 2

=

= 7.2867 in.wg

H 12.47 60.0

36.5

820

1000

0.075

0.072

0.99684

0.99426c

5 3

=

= 86.189 hp




60004-1893 U.S.A.


PAGE 10 OF 10

7/27/2019 Amca 99

18/85

ABSOLUTE PRESSURE Pressure above a perfect vacuum; the sum of gauge pressure and atmosphericpressure.

ABSOLUTE ROUGHNESS A measure of surface unevenness; the distance between high and low pointson a surface.

ACFM (ACTUAL CUBIC FEET PER MINUTE) Actual volume airflow rate through a plane of measurement,at the existing air density, expressed in ft

3/min.

ACMS (ACTUAL CUBIC METERS PER SECOND) - Actual volume airflow rate through a plane ofmeasurement, at the existing air density, expressed in m

3/s.

ACTUATOR (OPERATOR) A mechanism attached to a damper or adjustable louver to move its blades, orattached to a vaneaxial fan to change impeller blade pitch. An actuator may be manually, electrically,

pneumatically or hydraulically powered.

ACOUSTIC ATTENUATION DEVICE Any component having sound absorption as its primary function.

ADJUSTABLE PITCH The ability to mechanically alter the angle (pitch) of an impeller blade with theimpeller at rest.

AIR CURTAIN (AIRSTREAM) A directionally-controlled stream of air, moving across the entire height andwidth of an opening, which reduces the infiltration or transfer of air from one side of the opening to the otherand/or inhibits the passage of insects, dust, or debris.

AIR CURTAIN AVERAGE CORE VELOCITY The average of several air curtain core velocities measuredalong the width of the air curtain.

AIR CURTAIN CORE VELOCITY The peak air velocity of the air curtain as measured across the air curtaindepth at a specified distance from the discharge nozzle.

AIR CURTAIN DEPTH The airstream dimension perpendicular to both the height and width of the openingbeing protected.

AIR CURTAIN UNIT EFFICIENCY The ratio of the air curtain output air power to the power input to themotor, expressed as a percentage.

AIR CURTAIN UNIT RATED THROW The distance away from an air curtain unit discharge nozzle to apoint where a specified minimum air velocity is achieved.

AIR CURTAIN UNIT VELOCITY PROJECTION The average air curtain core velocity at specified distancesfrom the air curtain unit discharge nozzle.

AIR CURTAIN WIDTH The airstream dimension perpendicular to the direction of airflow and parallel to thewidth of the opening being protected.

AIR (GAS) DENSITY The mass per unit volume of air or gas.




60004-1893 U.S.A.

THE AMCA VOCABULARY:DEFINITIONS

BSR AMCASTANDARD99-0066-01

PAGE 1 OF 17

7/27/2019 Amca 99

19/85

AIRFLOW RATE See VOLUME AIRFLOW RATE orMASS AIRFLOW RATE.

AIRFOIL (1) A shape such that, when it is moved through air, has greater lift than drag. (2) A blade or vanehaving a streamlined shape.

AIR SYSTEM An assembly of connected ducts, filters, conditioning devices, dampers, louvers and fans forthe purpose of moving air from one place to another in a controlled fashion.

AIR THROW The horizontal or vertical axis distance an air stream travels after leaving an air outlet beforethe air velocity is reduced to a specific terminal value.

AMCA TESTING LABORATORY The associations testing laboratory, currently located in ArlingtonHeights, Illinois, or an independent laboratory licensed by AMCA to perform pre-certification performancetests and performance check tests.

AMCA ACCREDITED LABORATORY A laboratory equipped and staffed to conduct tests according to theappropriate AMCA-accepted test method, and which has been inspected by an AMCA staff engineer and dulyapproved for such testing.

ANECHOIC TERMINATION A device placed at the end of a test duct to prevent excessive reflection ofsound waves back into the duct, thus reducing interference with the sound waves being measured.

ATTENUATE To weaken a signal by reducing its amplitude.

ATTENUATION The amount by which sound amplitude is decreased as it travels from a sound source to areceiver located at a given point.

AVERAGE OUTLET VELOCITY (1) The airflow rate of a fan per unit area of the fan discharge, calculatedby dividing the airflow rate by the area of the fan discharge. (2) The free-delivery airflow rate of an air curtainunit divided by the face area of the discharge nozzle.

AXLE A shaft on which a damper or louver blade rotates.

BACKPLATE A circular plate, a component of a centrifugal fan impeller, which is attached to the fan huband serves as the major attachment for the impeller blades and as the means of transmitting torque to them.

BACKPLATE / CENTERPLATE LINER A narrow strip of steel, ceramic or synthetic material, installed insets, each attached to the backplate / centerplate of an impeller, adjacent to an impeller blade, for thepurpose of protection against erosion.

BALANCING The process of adding or removing mass on a rotor to move the center of gravity toward theaxis of rotation so as to reduce the unbalanced forces.

BAROMETRIC Pertaining to a barometer or the results obtained by using a barometer.




60004-1893 U.S.A.



PAGE 2 OF 17

7/27/2019 Amca 99

20/85

BAROMETRIC PRESSURE The absolute pressure exerted by the atmosphere at a location ofmeasurement.

BEARING LOSS The power loss resulting from friction in the main bearings of a fan or motor.

BLADE (1) The flow element of an impeller, which, by its shape and motion, generates airflow inside a fan,transforming impeller rotational energy to kinetic energy of airflow. (2) A movable surface in a damper orlouver that can be rotated to control airflow. (3) A stationary louver surface intended to restrict the passage ofwater, sound or other airborne materials, or to limit visual see-through.

BLADE ENTRY SEAL The sealing arrangement through which a damper blade passes in a guillotinedamper.

BLADE LINER A steel, ceramic or synthetic material piece having the same size and shape as the fan

blade, which covers the fan blade face in part or completely for the purpose of protection against erosion.

BLADE PASSAGE FREQUENCY The tone generated by the fans blades passing a fixed object andhaving a frequency given by: F(Hz) = (number of blades x fan revolutions per minute) / 60.

BLADE SUPPORT (1) A structural member, located inside the duct section of a guillotine damper frame,which supports the blade load when the damper is in the closed position; (2) A bracket that connects astationary louver blade to a rear-mounted structural support.

BLAST AREA The outlet area of a centrifugal fan less the projected area of its cut-off.

BONNET The portion of a guillotine damper that supports the damper blade when the damper is in the openposition. (1) OPEN TYPE: The damper blade is exposed to the atmosphere when blade is withdrawn from the

duct. (2) FULLY ENCLOSED (SEALED) TYPE: The entire bonnet encloses the damper blade when thedamper is in the open position.

CASING see HOUSING.

CENTERLINE SUPPORT A method of supporting a fan housing at its centerline when necessary to controldifferential thermal growth of the housing.

CENTERPLATE see BACKPLATE

CERTIFIED RATING A published performance rating of a product which AMCA has licensed to bear theAMCA Certified Performance Rating Seal. The seller of the product certifies that the rating is in accordancewith the appropriate AMCA-approved test method and that the requirements of the AMCA Certified RatingsProgram have been met.

CERTIFIED RATINGS PROGRAM The testing and licensing program established by AMCA International toverify the published performance ratings of a product produced by a seller.




60004-1893 U.S.A.



PAGE 3 OF 17

7/27/2019 Amca 99

21/85

CHAMBER (1) A test enclosure having a means for settling airflow, a cross sectional area larger than theinlet/outlet of test equipment connected to it, and the capability for measuring airflow rate and pressure. (2)

An enclosure used to regulate airflow and to absorb sound.

CLASS STANDARD An established minimum performance level of fan aerodynamic performance in termsof pressure and airflow rate.

COMPRESSIBILITY The characteristic of air or a gas whereby its density is a function of pressure.

COMPRESSIBILITY COEFFICIENT A thermodynamic coefficient used to correct the perfect gas equationwhen applied to air or gas.

CONTINUOUS LINE (CONTINUOUS BLADE) A term describing a louver constructed with blades thatpresent an uninterrupted horizontal or vertical line to complement or enhance architectural features.

CONTROLLABLE PITCH IMPELLER An axial impeller having a mechanism by which the pitch angle of allthe impeller blades can be changed while the impeller is rotating.

CORE AREA The front cross-sectional area (product of minimum width and minimum height) of the frontopening of a louver assembly with the blades removed.

CORE AREA VELOCITY The airflow rate through a louver divided by its core area.

CORROSION RESISTANT A term descriptive of materials or surface treatments that reduce corrosiveattack.

COUNTERBALANCE Weights or springs that offset the unbalanced weight of an eccentrically pivoted

damper blade.

COUNTERWEIGHT An adjustable or variable weight used to offset (counterbalance) an eccentricallypivoted damper blade.

CRITICAL SPEED, FIRST The rotational speed of a fan corresponding to the lowest natural frequency ofthe rotating fan impeller and shaft assembly when mounted on rigid supports without benefit of damping.

CUT-OFF A baffle or plate at the narrowest radial distance between the impeller and the housing near theoutlet of a centrifugal fan, and which directs air away from the impeller and minimizes recirculation of air.

CURB A roof penetration with a raised perimeter to seal against the weather and to facilitate installation ofroof mounted ventilation equipment such as a fan or hood.

DECIBEL A dimensionless number expressing, in logarithmic terms, a level of sound pressure or power.

DENSITY The mass per unit volume of a gas, liquid, or solid.




60004-1893 U.S.A.



PAGE 4 OF 17

7/27/2019 Amca 99

22/85

DETERMINATION The complete set of measurements for a particular point of operation for a product undertest. The measurements must be sufficient to determine all performance variables.

DIFFUSER (1) A duct discharge termination through a ceiling for the control and discharge of air. (2) Agradual transition of a duct, located at a fan outlet, which increases in cross sectional area and permits aportion of velocity pressure to be regained as static pressure; also known as an evas.

DISCHARGE ANGLE (1) The angle formed by the plane of an opening and the direction of an air curtain.(2) The angle of air or other gas flow exiting an impeller.

DISCHARGE NOZZLE An air curtain unit component that directs and controls the airstream.DISCHARGE NOZZLE DEPTH The inside nozzle dimension perpendicular to both the direction of airflowand the width of the airstream.

DISCHARGE NOZZLE WIDTH - The inside nozzle dimension perpendicular to the direction of airflow andparallel to the width of the airstream.

DISCHARGE STATIC PRESSURE See FAN STATIC PRESSURE

DRY-BULB TEMPERATURE - Air temperature measured by a temperature-sensing device withoutmodification to compensate for the effect of humidity.

DRY-BULB THERMOMETER An ordinary thermometer, especially one with an un-moistened bulb; notinfluenced by atmospheric humidity.

DUCT A passageway used primarily for conveying air or other gas at low pressure.

DUCTED FAN A fan having ductwork connected to the fan inlet, the fan outlet, or both.

DYNAMIC SIMILARITY A comparison that uses ratios of forces due to elasticity, viscosity, gravity, surfacetension, inertia and pressure to show equivalence between two similar fans. The variables compared are fanReynolds number, point of operation, compressibility, gas specific heat ratio, and tip speed Mach parameter.

EFFICIENCY A ratio of the useful energy provided by a dynamic application to the energy supplied to thesystem at a specific point of operation.

END REFLECTION A phenomenon that occurs whenever sound is transmitted across an abrupt change inarea, such as from the end of a duct into a room. When end reflection occurs, some of the sound is reflectedback into the smaller area of the duct and does not escape into the room.

ENERGY FACTOR The ratio of the total kinetic energy of airflow to the kinetic energy corresponding to theaverage air velocity.

EQUIVALENT DIAMETER The diameter of a circle having the same area as another geometric shape. Fora rectangular cross-section having width (a) and height (b), the equivalent diameter is given by: De =(4ab/)

0.5




60004-1893 U.S.A.



PAGE 5 OF 17

7/27/2019 Amca 99

23/85

EXPLOSION-PROOF APPARATUS Apparatus enclosed in a case that is capable of withstanding anexplosion of a specified gas or vapor which may occur within it, and of preventing the ignition of a specifiedgas or vapor surrounding the enclosure by sparks, flashes, or explosion of the gas or vapor within, and whichoperates at such an external temperature that a surrounding flammable atmosphere will not thereby beignited.

EXTERNAL STATIC PRESSURE see FAN STATIC PRESSURE RISE

EVAS see DIFFUSER

EXPANSION JOINT (FLEXIBLE CONNECTOR) A flexible member used to attach a fan inlet and/or outletto a connecting duct.

FACE AREA The total cross-sectional area of an air curtain unit discharge, a damper, louver, or duct.

FAN (1) A device that uses a power-driven rotating impeller to move air or gas. The internal energyincrease imparted by a fan to air or a gas is limited to 25 kJ/kg (10.75 BTU/lbm). (2) A device having a power-driven rotating impeller, without a housing, for circulating air in a room.

FAN AIR (GAS) DENSITY The density of air or gas corresponding to the total pressure, total temperature,and composition of the air or gas at a fan inlet.

FAN AIRFLOW RATE The volume airflow rate at a fan inlet at fan air density.

FAN APPURTENANCES Accessories added to a fan for the purpose of control, isolation, safety, staticpressure regain, erosion protection, etc. Common appurtenances include inlet box(es), inlet box damper,variable inlet vane, outlet damper, vibration isolation base, inlet screen, belt guard, evas or diffuser, sound

attenuator, erosion protection, and turning gear.

FAN BOUNDARIES Limits defining the interfaces between the fan and the remainder of the air system anddelineated as the planes perpendicular to the airstream as it enters and leaves a fan. Various appurtenances,such as an inlet box, inlet vane, inlet cone, silencer, screen, rain hood, damper, evas or diffuser, may beincluded as part of a fan between the inlet and outlet boundaries.

FAN EFFICIENCY, STATIC see FAN STATIC EFFICIENCY

FAN EFFICIENCY, TOTAL see FAN TOTAL EFFICIENCY

FAN EQUIPMENT An assembly of a fan and its various appurtenances, as defined by the fan boundaries.

FAN IMPELLER POWER The power delivered to a fan impeller, specifically, the fan shaft power minus thebearing loss.

FAN INLET The plane perpendicular to an airstream where the airflow first meets the inlet cone or the inletbox furnished by the fan manufacturer.




60004-1893 U.S.A.



PAGE 6 OF 17

7/27/2019 Amca 99

24/85

FAN INLET AREA The gross inside area measured at the plane(s) of the inlet connection(s). Forconverging inlets, the inlet area is considered to be a plane perpendicular to the airstream where it first meetsthe inlet cone.

FAN OUTLET The plane perpendicular to the airstream at the outlet opening of the fan or the manufacturer-supplied evas or diffuser.

FAN OUTLET AREA The gross inside area measured at the plane of the outlet opening. For a roofventilator, it is the gross impeller outlet area for centrifugal types or the gross housing area at the impeller foraxial types.

FAN PERFORMANCE CHARACTERISTICS The pressure rise (total or static) and the volume airflow rategenerated by a fan, and its power consumption at any given point of operation.

FAN POWER INPUT The power required to drive a fan and any elements in the drive train.

FAN POWER OUTPUT The useful power delivered to the air or a gas, and which is proportional to theproduct of the fan airflow rate, the fan total pressure, and the compressibility coefficient.

FAN REYNOLDS NUMBER A dimensionless parameter for judging dynamic similarity of flow ingeometrically similar fans, relating inertia to viscous forces, and given by:

Re = ND2 / 60

where: Re = fan Reynolds number, dimensionless = 3.14159N = fan rotational speed, rpmD = tip diameter of impeller, m (ft) = inlet air density, kg/m

3(lb

m/ft

3)

= absolute viscosity, Pas (lbm/fts)

FAN SHAFT The spindle on which a fan impeller is mounted, and upon which it rotates.

FAN SHAFT POWER The power delivered to the input end of a fan shaft, exclusive of drive losses otherthan that due to the fan or motor bearings, and fan shaft seal friction.

FAN SOUND POWER The ratio of sound power, radiated into a standard test duct, to a reference value of1.0x10

-12watts.

FAN ROTATIONAL SPEED The rotating speed of a fan impeller, in revolutions per minute.

FAN STATIC EFFICIENCY A parameter consisting of fan total efficiency multiplied by the ratio of static

pressure to total pressure, at a given point of operation.

FAN STATIC PRESSURE At a given point of fan operation, the difference between fan total pressure andfan velocity pressure; the difference between static pressure at fan outlet and total pressure at fan inlet.




60004-1893 U.S.A.



PAGE 7 OF 17

7/27/2019 Amca 99

25/85

FAN STATIC PRESSURE RISE At a given point of fan operation, the increase in static pressure betweenfan inlet and fan outlet.

FAN TOTAL EFFICIENCY At a given point of fan operation, a ratio equal to the fan power output divided bythe power input to the fan.

FAN TOTAL PRESSURE At a given point of fan operation, the difference between total pressure at fanoutlet and fan inlet.

FAN VELOCITY PRESSURE The pressure corresponding to the average air velocity at a specified fanoutlet.

FILTER A device used to separate vibration on the basis of frequency.

FIXED PITCH A term descriptive of an axial impeller having all blades permanently secured at a given pitchangle.

FLASHING A sheet metal strip placed at the junction of intersecting building surfaces to resist the entranceof water.

FLOW RATE The volume flow rate of a gas at a specific gas density.

FOUNDATION STIFFNESS The lateral spring constant of the foundation as referenced to the fan bearingcenterline. Factors to be considered include the foundation block, the sub-soil, piles, if any, the concrete piersupporting the steel fan supports, and the interface between the steel supports and the concrete pier.

FREE AREA The minimum louver or damper area through which air can pass.

FREE AREA VELOCITY The airflow rate through a damper or louver divided by its free area.

FREE AIR see FREE AIR DELIVERY

FREE AIR DELIVERY That point of operation where a fan or an air curtain unit operates against zero staticpressure.

FREQUENCY The number of complete cycles in a unit of time. When applied to sound, it is the number ofcomplete pressure wave fluctuations which pass a given point each second. For a time period of seconds,the unit of measure is the Hertz (Hz).

GAS DENSITY The mass per unit volume of air or gas.

GAUGE PRESSURE The value of a pressure when the reference pressure is the barometric pressure atthe point of measurement.

GEOMETRIC SIMILARITY A comparison of the ratio of corresponding dimensions of two fans, includingangles, each dimension proportioned to impeller diameter. The proportional dimensions include materialthickness, clearances, and roughness, as well as airflow passages




60004-1893 U.S.A.



PAGE 8 OF 17

7/27/2019 Amca 99

26/85

GUIDE VANES Curved stationary vanes (stator vanes) located at the impeller inlet or discharge to reduceswirl and to enhance static pressure regain from the airflow.

HEAD (1) The upper or highest frame member of a damper or louver. (2) Fluid pressure expressed interms of height of water column.

HOUSING A stationary enclosure for an impeller, having an inlet and an outlet, and designed to direct theflow of air through the impeller and towards the outlet. The housing may also affect the energy transformationof the airstream.

HOUSING SIDEPLATE LINER A narrow strip of steel, ceramic or synthetic material fastened to thesideplate of a centrifugal fan housing at the intersection of the sideplate and the scroll, for the purpose oferosion protection.

HUB The center portion of an impeller, by which the impeller is connected to its shaft, and through whichthe shaft transmits torque to the impeller.

HYDRAULIC DIAMETER A characteristic dimension in Reynolds number calculations, taken normal to thefluid flow and equal to four times the cross-sectional area divided by the wetted perimeter.

IDENTICAL MODULES A standard for performance comparison wherein two fans have identicalaerodynamic designs, including fan impeller diameter, impeller tip width, number of blades, blade pitch, bladearc, blade size, scroll configuration and angle of expansion, rotational speed, distance to the next adjacent fanor barrier, and essentially the same inlet and outlet conditions. Motor frame size and drive are be the same ifthese are within the airstream.

IMPELLER The assembled rotating component of a fan, designed to increase the energy level of the

airstream.

INDEPENDENT ACCREDITED LABORATORY With respect to the AMCA International AccreditedLaboratory Program, a laboratory not owned by or affiliated with an AMCA member company but which hasbeen designated as an Accredited Laboratory by the AMCA Board of Directors for the purpose of performingpre-certification performance tests, performance check tests, and challenge tests.

INLET BOX A component, similar to a duct elbow, which can be added to the inlet of an axial or centrifugalfan for the purpose of directing airflow into the fan inlet in line with the axis of the fan shaft.

INLET FLOW PROFILE The shape of the air velocity profile just upstream of a fan inlet and which indicatesvariation in airflow through a plane extending across the airflow passage.

INTERFERENCE FIT A mating condition of two components wherein the limits of size are so specified thatan interference always results when the mating components are assembled; either a press fit or a shrink fit.

JACKSHAFT (1) A separate shaft used to operate multiple louver or damper sections. (2) An intermediateshaft between motor and fan impeller.




60004-1893 U.S.A.



PAGE 9 OF 17

7/27/2019 Amca 99

27/85

JAMB The vertical frame member on either side of a damper or louver.

JOURNAL The part of a rotor that is in contact with or supported by a bearing in which it revolves.

KINEMATIC SIMILARITY A relationship between airflow systems requiring that the ratios of allcorresponding velocities be similar for two fans to be considered similar. This includes correspondingvelocities of the air or gas and corresponding peripheral velocities of the impellers. The directions and pointsof application of all corresponding vectors must be identical.

KINEMATIC VISCOSITY The viscosity of a fluid divided by its mass density.

LINKAGE A system of bar links, pivots, and rotating members for the transfer of force and motion to louverand damper blades.

MACH NUMBER A ratio of fluid velocity to the speed of sound in the same fluid.

MAKE-UP AIR Outside air that is brought into a building to replace exhaust air and building leakage(exfiltration), or process exfiltration.

MASS AIRFLOW RATE The mass of air that passes through a given area in unit time and is obtained bymultiplying the volumetric airflow rate by the air density.

MAXIMUM CONTINUOUS RATING The maximum continuous airflow, pressure and temperature values atwhich the fan is specified to operate.

MEASUREMENT PLANE The radial plane in the test duct, generally perpendicular to the airflow, at whichmeasurement(s) is(are) obtained.

MECHANICAL RUN-OUT The total actual variation in the location of a shaft surface during a completerevolution as determined by a stationary measuring device such as a dial indicator.

MOTOR POWER The power delivered from the output shaft of the motor.

MULLION A frame support member between multiple section louvers or dampers.

NATURAL FREQUENCY The frequency at which a system oscillates in the absence of external forces andexhibits a maximum response to an external input.

NON-DUCTED FAN A fan without ductwork connected to either its inlet or its outlet.

NOSE PIECE (REPLACEABLE) A sacrificial metal, ceramic or synthetic material piece added to theleading edge of an airfoil blade for the purpose of erosion protection.

NOZZLE A flow-measuring device having a streamlined entrance and a sharp-edged outlet perpendicular toits longitudinal axis. Airflow rate through a nozzle is proportional to the square root of the differential pressureacross the nozzle and the throat area of the nozzle.

OCTAVE BAND A range of frequencies between two end frequencies selected such that the centerfrequency is twice the center frequency of the next lowest band.




60004-1893 U.S.A.



PAGE 10 OF 17

7/27/2019 Amca 99

28/85

ONE-THIRD OCTAVE BAND A band of frequencies resulting from the division of an octave band into threesmaller bands.

OPPOSED BLADE DAMPER A damper constructed such that adjacent blades rotate in opposite directions.

OUTLET VELOCITY The average velocity of air emerging from an outlet, measured in the plane of theoutlet.

OUTLET VELOCITY UNIFORMITY A measure of test velocity variation equal to the standard deviation ofmeasured test velocities divided by the average of those test values, the ratio being subtracted from one(1.0).

PACKING Sealing material used to minimize or eliminate leakage at the shaft penetration of a housing orframe.

PARALLEL BLADE DAMPER A damper in which the blades rotate in the same direction.

PARTIAL BLADE LINER A narrow piece of metal, ceramic or synthetic material located at the intersectionof the impeller blade and backplate or centerplate for erosion protection.

PEAK DESIGN TEMPERATURE The maximum temperature at which a piece of equipment can operate fora specific duration.

POINT OF OPERATION The relative position on a fan or air curtain unit performance curve correspondingto a particular airflow rate, pressure, power consumption, and efficiency.

POINT OF RATING The specified fan operating point on its characteristic curve.

POWER RATING - The amount of power consumed by the drive motor(s) of the air curtain unit.

PRESSURE (1) Force per unit area; (2) Stress per unit volume of a fluid, corresponding to the energy perunit volume of a fluid.

PRESSURE DIFFERENTIAL Commonly, the change in static pressure across a device. The term isseldom if ever associated with velocity pressure or total pressure.

PRESSURE DROP Commonly, (1) The static pressure difference between two points in an airflow system,due to frictional resistance along system walls, or in passing over or through an obstruction; (2) A measure ofthe resistance to airflow across a device, which is expressed as the difference in static pressure across thedevice at a specific rate of airflow. The term is seldom if ever associated with velocity pressure or totalpressure.

PRESSURE LOSS The change in total pressure due to friction and turbulence.

PRODUCT LINE A product or series of product sizes with a common design purpose and generally similaraerodynamic features, but not necessarily homologous, cataloged under the same product description orname and/or identifying references.




60004-1893 U.S.A.



PAGE 11 OF 17

7/27/2019 Amca 99

29/85

PROPELLER A bladed device (impeller) that rotates on a shaft to produce a useful thrust of air or gas in adirection parallel with the shaft axis.

PSYCHROMETRIC Pertaining to the measurement and determination of water vapor content inatmospheric air.

RACKING The twisting of a frame out of its intended planar arrangement.

RATE OF TEMPERATURE CHANGE The increase or decrease in temperature per unit time.

RELATIVE ROUGHNESS FACTOR The measurement of surface unevenness, from peaks to valleys,divided by a dimension such as pipe diameter.

RESONANCE A condition of high vibration response that occurs when the frequency of an external driving

force approaches the natural frequency of the system.

RESONANT FREQUENCY See NATURAL FREQUENCY

RESONANT SPEED, DESIGN The calculated fan rotational speed corresponding to the lowest naturalfrequency of the combined fan shaft in bending, considering the fan rotor, oil film, bearing housing, andbearing supports, but excluding the effect of foundation stiffness.

RESONANT SPEED, INSTALLED The calculated fan rotational speed corresponding to the lowest naturalfrequency of the combined fan shaft in bending, considering the fan rotor, oil film, bearing housing, andbearing supports, and including the effect of foundation stiffness.

REYNOLDS NUMBER A dimensionless number representing the ratio of internal forces to viscous forces at

a particular point of a fluid in motion. Its value is calculated as: the fluids density times the flow velocity at thepoint of interest, multiplied by a characteristic length, and the product divided by the fluids viscosity.

Re = (VD / ) = (VD / )

where: Re = Reynolds number, dimensionless = inlet air density, kg/m

3(lbm/ft

3)

V = Velocity of air, m/s (ft/s)D = Diameter, m (ft) = absolute viscosity, Pas (lbm/fts) = kinematic viscosity, m2/s (ft2/s)

ROTOR An assembly consisting of a fan impeller mounted on its shaft.

SAMPLING TUBE A windscreen tube designed for minimum sensitivity to airflow noise, and designed to beattached to a standard 13 mm (0.5 in.) microphone.

SCROLL LINER A metal, ceramic or synthetic material piece attached to a fan scroll for the purpose oferosion protection.




60004-1893 U.S.A.



PAGE 12 OF 17

7/27/2019 Amca 99

30/85

SEAL AIR (1) Air introduced into the air chamber of an isolation damper at a pressure higher than that ofgases either upstream or downstream, to prevent passage of duct gas across the enclosed damper space. (2)Pressurized air introduced into a shaft seal chamber to function as a leakage barrier to process gas. (3)Pressurized air introduced into a housing around a furnace to prevent the escape of products of combustion.

SEATING TORQUE - The amount of torque required to compress the seals or hold the louver or damperblades in the closed position.

SEISMIC QUALIFICATION Documentation supplied with an item of equipment that substantiates the abilityof the equipment to withstand the effects of an earthquake of specified magnitude.

SHAFT A cylindrical piece of metal, usually solid, that is used to support a rotating part such as a fanimpeller, and transmit torque to the supported component.

SHAFT SEAL A device that creates a barrier over the circumference of a fan shaft or damper axle for thepurpose of limiting or preventing the passage of air or gas across the barrier.

SHALL and SHOULD In this and other AMCA standards, the word shall is understood to be mandatory,and the word shouldas advisory.

SHUT-OFF That point of fan operation where the airflow rate is zero.

SHUTTER See BACKDRAFT DAMPER.SILL The bottom or lowest frame member of a louver or damper.

SIMILARITY A ratio used to compare a given characteristic of two fans; when equated to unity, similarity is

said to exist for that characteristic. The ratios considered may be for dynamic, geometric, and/or kinematiccharacteristics

SKEWING The deviation of a frame from rectangularity or from a straight line.

SONE (1) A unit of loudness corresponding to the loudness of a sound at a frequency of 1000 Hz and asound pressure of 0.02 microbar (40 dB); (2) A linear unit of sound loudness based on the perception of theaverage human ear.

SOUND An auditory sensation produced by the vibration of matter that results in propagation by variation ofpressure, particle displacement or density through an elastic medium.

SOUND ATTENUATION - See ATTENUATION

SOUND POWER LEVEL The acoustic power rating of a sound source measured in decibels and equal toten times the logarithm (base 10) of the acoustic power in watts with reference to 1x10

-12watts.




60004-1893 U.S.A.



PAGE 13 OF 17

7/27/2019 Amca 99

31/85

SOUND PRESSURE LEVEL The acoustic pressure at a point in space where a microphone or a listenersear is situated. One decibel (dB) of sound pressure is defined as 20 times the logarithm (base 10) of thesound pressure fluctuation with reference to 0.0002 microbars (20 micropascals).

SPECIFIC HEAT The ratio of the amount of heat required to raise the temperature of a given mass of anysubstance one degree to that amount of heat required to raise the temperature of an equal mass of astandard substance one degree (usually water at 15C (59F)).

SPECIFIC HEAT AT CONSTANT PRESSURE The quantity of heat required to raise the temperature of aunit mass of a substance one degree at constant pressure.

SPECIFIC HEAT AT CONSTANT VOLUME - The quantity of heat required to raise the temperature of a unitmass of a substance one degree at constant volume.

SPECIFIC HEAT RATIO The numeric ratio of the specific heat of a gas at constant pressure to that of thesame gas at constant volume.

STALL LIMIT That point near the peak of an axial fans pressure curve (for a particular blade angle) thatcorresponds to the minimum airflow at which the fan can be operated without instability.

STANDARD AIR Air having a density of 1.2 kg/m3

(0.075 lbm/ft3), a specific heat ratio of 1.4, a viscosity of

1.819E-05 Pas (1.222E-05 lbm/ft-s) and an absolute pressure of 101.325 kPa (406.78 in. wg). Air at 20C

(68F), 50% relative humidity, and 101.325 kPa (29.92 in. Hg) has these properties, approximately.

STANDARD AIR DENSITY A density of 1.2 kg/m3

(0.075 lbm/ft3), corresponding approximately to air at

20C (68F), 50% relative humidity, and 101.325 kPa (29.92 in. Hg).

STANDARD ATMOSPHERIC PRESSURE A reference pressure (assumed to be at sea level) defined bythe International Civil Aeronautics Organization (ICAO) as 101.325 kPa. In I-P units the corresponding valuesare 14.696 psi or 29.921 in. Hg at 32F.

SCFM (STANDARD CUBIC FEET PER MINUTE) The volume airflow rate through a plane ofmeasurement, corrected to standard air density of 0.075 lbm/ft

3.

SCMS (STANDARD CUBIC METERS PER SECOND) - The volume airflow rate through a plane ofmeasurement, corrected to standard air density of 1.2 kg/m

3.

START-OPEN PRESSURE The differential pressure across a backdraft or pressure relief damper at whichthe blades begin to rotate towards the open position.

STATIC PRESSURE That portion of air pressure that exists by degree of compression only.

STATIC REGAIN (1) The conversion of velocity pressure at a small area into static pressure at a largerarea by slowing the gas or air velocity by means of a diffuser or an evas; (2) The amount of static pressuregained by conversion of velocity pressure to static pressure.




60004-1893 U.S.A.



PAGE 14 OF 17

7/27/2019 Amca 99

32/85

STATIC TEMPERATURE The temperature that exists by virtue of the internal energy of the air alone. If aportion of the energy is converted to kinetic energy, the static temperature is decreased accordingly.

STOP An angle or rigid strip used to close the gap between a blade edge and frame at the top and bottomof a damper or a louver.

SUB-FRAME (BUCKFRAME) A frame installed in a wall opening to facilitate the mounting or removal of alouver.

SUB-SILL (EXTENDED SILL) A shaped metal flashing installed at the bottom of a wall opening to facilitatewater drainage.

SURGE LIMIT A point near the peak of a centrifugal fans performance pressure curve that defines theminimum airflow rate at which a fan can be operated without instability.

SYSTEM EFFECT FACTOR A decrease in fan performance capability, observed as a pressure loss thatresults from the effect of fan inlet restrictions / obstructions, fan outlet restrictions or other conditionsinfluencing the performance of the fan when it is installed in a system.

SYSTEM PRESSURE LOSSES The sum of the static pressure losses due to friction, shock, dissipation ofvelocity pressure at the system discharge and the static pressure differences between the entry anddischarge openings of an air system. System pressure losses are total pressure losses.

TEMPERATURE, DESIGN The minimum or maximum temperature at which a fan or damper can becontinuously operated.

TEMPERATURE, DESIGN AIR (1) That air temperature at which a heating, ventilating or air conditioning

system or apparatus is designed to maintain (indoor design) or to operate against (outdoor design). Outdoordesign temperature is usually give for both minimum and maximum conditions. (2) The maximum and/orminimum gas temperature for specification of process control equipment.

TEMPERATURE, OPERATING The air temperature in the fan under actual normal operating conditions.

TERMINATING DUCT Where a fan under test for sound and equipped with both inlet and outlet ducts, oneduct contains the sound pressure measurement device. The duct on the opposite side may be equipped withan anechoic termination and is known as the terminating duct.

TEST A series of determinations for various points of operation of a fan, damper, louver, airflowmeasurement station or air curtain unit.

TEST BLOCK The operating test point above and beyond the Maximum Continuous Rating thatdemonstrates the fan margin to the customer.




60004-1893 U.S.A.



PAGE 15 OF 17

7/27/2019 Amca 99

33/85

TEST DUCT (1) A duct section of prescribed length that is defined originally in ANSI/AMCA 210 (andsubsequently in AMCA standards 500D and 500L), and which is used to control and measure airflow rate andpressure. (2) A duct that functions as the sound measurement section and has an anechoic termination.

TIP SPEED The peripheral velocity at the tips of a fan impeller.

TIP SPEED MACH PARAMETER A dimensionless number expressing the ratio of a fan impellersperipheral velocity to the local velocity of sound at the fan inlet.

TOTAL PRESSURE The air pressure that exists by virtue of the degree of compression and rate of motionof flowing air. It is equal to the algebraic sum of the velocity pressure and the static pressure at a point.Thus, if the air is at rest, the total pressure will equal the static pressure.

TOTAL TEMPERATURE The temperature that exists by virtue of the internal and kinetic energy of the air.

If the air is at rest, the total temperature will equal the static temperature.

TORSIONAL CRITICAL SPEED The fan rotational speed that corresponds to the natural frequency intorsion of its power transmission system, including driver, drive train components, and the fan rotor.

TURNING GEAR An intermittent fan drive arrangement consisting of a motor, a speed reducer, and aunidirectional engagement clutch fastened to the outboard end of a fan shaft or motor shaft through a flexiblecoupling. The turning gear rotates the complete rotating assembly at a low speed to prevent distortion in therotor assembly due to uneven cooling. The turning gear may be sized to have the capability of starting themain rotor. Axial fans generally do not require a turning gear.

VANE (1) A stationary curved surface used to straighten or direct airflow, (2) A flat or curved surface thatcan be rotated about an axis to direct airflow.

VARIABLE PITCH IMPELLER An axial impeller having a mechanism or mechanisms by which the pitchangle of each impeller blade can be changed while the impeller is at rest.

VELOCITY DISTORTION PARAMETER AXIAL A parameter characterizing air velocity distortion within ameasuring plane at a constant radius in a circular duct, and in a direction parallel to the fan shaft centerline ina rectangular duct. It is expressed as a percentage of the mean velocity of the air at the fan inlet

VELOCITY DISTORTION PARAMETER INLET FLOW An indicator of the variation in the airflow field atthe inlet plane of a fan. It is calculated by applying the principle of standard deviation, using velocitymeasurements taken in a matrix form in a transverse plane across the flow field and expressed as apercentage of the mean velocity of the air at the fan inlet.

VELOCITY DISTORTION PARAMETER TRANSVERSE A parameter characterizing the air velocitydistortion within a measuring plane in a radial direction for a circular duct and at a right angle to the fan shaftin a rectangular duct. It is expressed as a percentage of the mean velocity of the air at the fan inlet.

VELOCITY PRESSURE That portion of air pressure that exists by virtue of rate of motion only.




60004-1893 U.S.A.



PAGE 16 OF 17

7/27/2019 Amca 99

34/85

7/27/2019 Amca 99

35/85

ABRASION RESISTANT FAN (or DAMPER) - A fan or damper designed to minimize abrasion, having parts

subject to wear constructed of materials that are abrasion resistant and/or are easily replaceable.

ACOUSTICAL DUCT SILENCER An air duct section containing sound absorbing materials that reduce the

transmission of sound through the air passage.

ACOUSTICAL LOUVER - A louver incorporating sound absorbing material to reduce sound transmission

across an opening.

ADJUSTABLE LOUVER - A louver in which the blades may be rotated either manually or mechanically.

AIR CURTAIN UNIT An air moving device that produces a curtain of air.

AIR DIFFUSER - A duct discharge termination located in a ceiling and arranged to direct airflow, or to promoteair mixing.

AIRFLOW MEASUREMENT STATION - A multiple-point sensing device used to measure the airflow in a duct

and which consists of a single or multiple array of sensors in permanent position across the duct system.

1. DIFFERENTIAL (VELOCITY) PRESSURE OUTPUT TYPE - Converts air velocity into a differential

(velocity) pressure signal which correlates to the velocity or volume of air flowing through a duct.

2. ELECTRONIC OUTPUT TYPE - Converts air velocity into an electronic signal that correlates directly and

proportionally to the velocity of the air volume flowing through a duct.

AIR-HANDLING UNIT - A packaged assembly of air-conditioning components (coils, filters, fan, humidifier, and

so forth) that provides for treatment of air before it is distributed.

1. BLOW-THROUGH Fan is mounted upstream of a heat exchanger.2. CENTRAL STATION Does not include a source of heating or cooling.

3. COOLING Includes a means for cooling air.

4. COOLING HEATING Includes the means for both heating and cooling air.

5. DRAW-THROUGH Heat exchanger(s) are mounted upstream of the fan.

6. HEATING Includes a means for heating air.

AXIAL FAN - A fan in which the airflow is predominately parallel to the impellers axis of rotation.

BACKDRAFT DAMPER - A damper which, when mounted in a duct or opening, permits airflow in one direction

only.

BALANCING DAMPER - A damper used to regulate the airflow in an air system.

BAROMETRIC DAMPER - A backdraft damper having an adjustable start-open pressure and used for gravity

ventilation or other low velocity applications.




60004-1893 U.S.A.

THE AMCA VOCABULARY:PRODUCTDEFINITIONS

An American National StandardApproved by ANSI on August 6, 2003

ANSI/AMCASTANDARD99-0068-03

PAGE 1 OF 7

7/27/2019 Amca 99

36/85

BATH FAN A fan used to exhaust air from a bathing / toilet area for the primary purpose of moisture and/or

odor removal.

BIFURCATED FAN - A direct-driven fan having the airstream-mounted drive motor separated from the

airstream by means of a compartment or tunnel.

BLAST DAMPER A damper that reacts to sudden pressure changes in an air system, to either relieve the air

pressure, or to isolate a space from the rapid pressure rise.

BLOWER A fan that operates against air system resistance downstream of the fan; a Forced Draft Fan.

BOX FAN A fan used in an office or residential application and having the motor and impeller enclosed in an

approximately square box having a handle.

CAST-IRON VOLUME FAN A fan having a housing made of cast iron.

CENTRIFUGAL CEILING/WALL EXHAUSTER A factory-assembled fan consisting of one or more centrifugal

impellers connected to a motor and enclosed in a housing; usually including an inlet grille and a backdraft

damper, and intended for installation in a ceiling or a wall.

CEILING DAMPER - A device intended to protect an air duct opening in a fire-rated ceiling assembly and which

operates to interrupt airflow automatically in the event of fire to restrict the passage of flame and heat.

CEILING EXHAUST FAN - A fan mounted in a ceiling and which serves to exhaust air from a room.

CEILING FAN - A propeller fan supported from a ceiling and which serves to circulate air within a given space;

also known as an air circulation fan.

CENTRIFUGAL FAN - A fan in which a gas, such as air, is moving in a primarily axial direction upon entering

the impeller and has its direction changed by the impeller blades to an essentially radial flow at the impeller

discharge. The impeller is generally contained in a volute housing

CIRCULATING FAN - A fan used for moving air within a space, and which is unconnected to any ducting, and is

usually without a housing.

COMBINATION LOUVER-DAMPER - A louver having both stationary and eccentrically pivoted movable blades

that can be opened and closed.

COMBUSTION AIR BLOWER A centrifugal fan that serves to supply pressurized air to a burner system

combusting gas, oil, or other fuel.

CONTRA-ROTATING FAN - An axial flow fan having two impellers arranged in series and rotating in opposite

directions.

CONVEYING FAN - A fan suitable for conveying solids (e.g., wood chips, textile waste, pulverized material, or

dust).




60004-1893 U.S.A.




PAGE 2 OF 7

7/27/2019 Amca 99

37/85

CORROSION RESISTANT FAN A fan having an impeller and housing constructed of materials that resist

corrosion, or having airstream or exterior components surface-treated to minimize the corrosive effect of certain

chemicals or compounds.

CROSS-FLOW FAN - A fan in which the fluid path though the impeller is in a direction substantially at right

angles to its axis with air both entering and leaving radially at its periphery.

DAMPER A device used to vary the volume of air passing through an opening, duct or confined cross-section

by varying the cross-sectional area.

DESTRATIFICATION FAN - An air circulation fan located in a room to move warm air from the ceiling

downward or to mix air in a given space.

DOWNDRAFT FAN An exhaust fan that serves to remove heated air and moisture by inducing air to flowdown to a fan inlet located below a cooking surface.

DUST FAN - A fan that serves to extract dust-laden air.

ELECTRIC AIR HEATER A space heater having electric resistance elements as the heat source and a fan for

the circulation of heated air.

EVAPORATIVE COOLER An assembly consisting of a fan or fans and other necessary equipment to cool by

evaporation the airflow created by the fan(s).

FACE-AND-BYPASS DAMPER A pair of dampers that operate together but with opposite motion, to direct an

airstream either through or around a heat transfer device.

FIRE DAMPER - A device arranged to interrupt airflow automatically through part of an air system so as to

restrict the passage of flame, and installed in a fire-related wall or floor to close automatically in the event of a

fire in order to maintain the integrity of the fire-rated separation.

FIXED LOUVER - A louver having immovable blades.

FLUE GAS DESULFURIZATION FAN - An additional induced draft fan placed in series with and downstream of

an induced draft fan to overcome losses of retrofit air pollution control devices.

FORCED DRAFT FAN A high pressure / high volume fan used to supply primary and secondary combustion

air to a furnace / boiler and its exhaust system. See also: COMBUSTION AIR BLOWER and BLOWER.

GAS RECIRCULATION FAN An induced draft fan used to redirect boiler gases through the furnace,superheaters, economizers and to overcome losses in connecting ductwork

GAS TIGHT FAN (DAMPER) A fan or damper constructed with seals and gaskets at all housing penetrations

to minimize gas leakage through the housing and appurtenances.

GENERAL PURPOSE FAN - A fan suitable for handling clean air that does not exceed a temperature of 80C

(176F), or 40C (104F) if the motor or the fan bearings are in the airstream.




60004-1893 U.S.A.




PAGE 3 OF 7

7/27/2019 Amca 99

38/85

7/27/2019 Amca 99

39/85

IN-LINE FAN A fan designed to be mounted between duct sections with air inlet and outlet being in an axial

direction.

ISOLATION DAMPER - A low leakage damper intended to regulate or stop the airflow in branches of a duct

system.

ISOLATION DAMPER, MAN-SAFE A damper containing an isolating system to seal off flue gases so that

men without breathing apparatus or other special equipment may safely enter the isolated section.

JET FAN - A fan mounted at the ceiling of a vehicular tunnel and which induces airflow by entrainment of air

with that streaming from the fan outlet.

KITCHEN FAN A centrifugal or axial fan located in a kitchen area and which serves to exhaust heat and

moisture.

LOUVER - A device comprising multiple blades which, when mounted in an opening, permits airflow but inhibits

the entrance of water or other elements.

MAKE-UP AIR UNITS - A packaged assembly consisting of a heat source and fan(s) serving to supply fresh,

tempered, replacement air for that exhausted from a building. MATERIAL HANDLING FAN - see CONVEYING FAN

MECHANICAL DRAFT FAN A generic term of classification applying to any of the fans used in a furnace or

boiler system, including Forced Draft, Induced Draft, Primary Air, Overfire Air, Gas Recirculation, Seal Air, and

Flue Gas Desulfurization fans.MIXED FLOW FAN - A fan in which the airflow through the impeller is intermediate between the centrifugal and

axial flow types, the air moving both axially and radially.

MULTI-STAGE FAN - A fan having two or more impellers that work in series, with guide (stator) vanes between

the impellers.

NON-CLOGGING FAN - A fan having an impeller designed to minimize clogging by virtue of its shape or by use

of special materials. The fan may also incorporate other features to allow use of cleaning sprays and to facilitate

the removal of any resulting materials.

OVERFIRE AIR FAN A fan that serves to deliver additional (excess) air downstream of the fuel burners in a

boiler for the purpose of improving combustion.

PACKAGED FAN see UTILITY SET

PARTITION FAN - A fan installed in or on a partition and used for moving air from one air space to another.

PASSIVE THROUGH-THE-WALL INLET A device mounted in an outside wall of a building and which serves

to allow the entrance of ambient air to replace that which has been exhausted.




60004-1893 U.S.A.




PAGE 5 OF 7

7/27/2019 Amca 99

40/85

7/27/2019 Amca 99

41/85

SEAL AIR FAN (1) A fan that serves to pressurize an enclosure around a furnace or boiler to prevent the

escape of burned gases into ambient air. (2) A fan supplying air to a shaft seal chamber as a leakage barrier to

process gas. (3) A fan supplying air to the chamber of an isolation damper to prevent the passage of duct gases

across the enclosed space.

SIGHT-PROOF LOUVER - A louver that cannot be seen through from any direction.

SMOKE (LEAKAGE RATED) DAMPER - A damper intended to: (1) restrict the spread of smoke in HVAC

systems that are designed to be automatically shut down in the event of a fire or (2) control the movement of

smoke when the HVAC system is operational in a building having a smoke management system.

SMOKE MANAGEMENT FAN (SMOKE VENTILATION FAN) A fan that serves to exhaust smoke and heated

air from a building and which may be certified to remain operable after exposure to a given temperature for a

given duration.

SPARK RESISTANT FAN (or DAMPER) - A fan or damper constructed to reduce the potential for spark

generation when the airstream is potentially explosive.

STATIC VENTILATING DEVICE A device that passively exhausts air from a building by venting.

TABLE FAN An air circulator fan intended for use on a desk, table or counter top; it may also be provided with

the means for being mounted to a wall.TEMPERATURE CONTROL DAMPERS A pair of dampers intended to be operated together to provide a total

airflow at a given temperature. Two different airflows are regulated by simultaneous damper adjustments.

TUBE AXIAL FAN - An axial flow fan with the impeller in a cylindrical housing and without guide vanes tostraighten the discharged air.

TUBULAR CENTRIFUGAL FAN - A fan having a centrifugal impeller within a cylindrical housing discharging

the air in an axial direction.

UTILITY SET - A centrifugal fan designed as a packaged unit, ready to run, either belt-driven or directly

connected to an electric motor.

VANE AXIAL FAN - A fan comprised of an axial impeller in a cylindrical housing having guide vanes located

upstream or downstream of the impeller, or both.

VENTILATOR - A device that serves to supply air into or exhaust air from a building.

VOLUME CONTROL DAMPER - A device which, when mounted in a duct or opening, is used to vary the

volume of air flowing through the duct or opening and which can be operated manually or mechanically, and can

have one or more blades.

WET GAS FAN - A fan that serves to move air that contains particles of water.

WHOLE-HOUSE FAN A fan mounted in the ceiling or attic wall of a house and from which it serves to exhaust

air and which incorporates a backdraft damper.




60004-1893 U.S.A.




PAGE 7 OF 7

7/27/2019 Amca 99

42/85

SYMBOL ORABBREVIATION DESCRIPTION SI I-P

A area of cross section m2

ft2

A duct width m ft

Ae area-orifice equivalent to system m2

ft2

Ao area-nozzle with no loss m2

ft2

ah absolute humidity, (mass)H20 / (mass)dry air kg/kg lbm/lbm

B minimum distance between the sill and bottom blade mm in.

B duct height m ft

BPF blade pass frequency Hz Hz

BW band width Hz Hz

b flow-induced absorption coefficient dB dB

C dynamic loss coefficient --- ---

C combined free field response correction dB dB

Cnozzle discharge coefficient --- ---

C minimum distance between adjacent blades mm in.

Cm constant for tip speed Mach number --- ---

Cn nozzle discharge coefficient --- ---

Cp specific heat at constant pressure J/kg-K Btu/lbm-F

Cv specific heat at constant volume J/kg-K Btu/lbm-F

C1 free field microphone correction response dB dB

C2 frequency response correction of sampling tube dB dB

(normal incidence)

C3 flow velocity correction for frequency response dB dB

required by sampling tube

C4 modal correction for the frequency response dB dB

required by sampling tube




60004-1893 U.S.A.

THE AMCA VOCABULARY:SYMBOLS BSR AMCASTANDARD

99-0070-01PAGE 1 OF 11

7/27/2019 Amca 99

43/85


c speed of sound m/s ft/s

D diameter of duct or impeller m ft

De equivalent diameter m ft

De/y ratio of straightener cell size (dia. to thickness of cell) --- ---

Dh hydraulic diameter m ft

DI diameter of intermediate duct m ft

DT diameter of terminating duct m ft

DVM digital voltmeter --- ---

D1-6 diameters along anechoic termination --- ---

d orifice diameter m ft

dBA estimated sound pressure level at a location --- ---

using "A" weighing network

E energy factor --- ---

Esystem resistance curve --- ---

Ei1-in duct inlet end correction dB dB

Eo1-on duct outlet end correction dB dB

Ev volts, direct current, output signal Vdc Vdc

of thermal flow sensor

e orifice plate end reflection dB dB

eper permissible specific unbalance m or (gmm)kg in. or (lb in.)/lb

ex per unit uncertainty in x --- ---

F beam load kg lbf

FLA full load amps amps amps

f coefficient of friction --- ---

f frequency Hz Hz




60004-1893 U.S.A.

THE AMCA VOCABULARY:SYMBOLS


PAGE 2 OF 11

7/27/2019 Amca 99

44/85


fc cut-off frequency Hz Hz

G water volume flow rate L/s gpm

G balance quality grade --- ---

g acceleration due to gravity m/s2

ft/s2

H fan power input kW hp

H actual louver height mm in.

Ha air power of air curtain kW hp

HL power transmission loss kW hp

Hm power input to motor kW hp

Hmo motor power output kW hp

Ho fan power output kW hp

Hr fan impeller power kW hp

Hsr fan shaft power kW hp

H/T axial fan hub-to-tip ratio --- ---

I index in transverse direction for velocity matrix --- ---

j index in axial direction for velocity matrix --- ---

K system effect factor --- ---

K loss coefficient relevant to a specific damper --- ---

design sample

KE friction chart correction factor for elevation --- ---

KM friction chart correction factor for roughness --- ---

Kp compressibility coefficient --- ---

KT friction chart correction factor for temperature --- ---

kW kilowatts, electric power kW kW




60004-1893 U.S.A.


99-0070-01PAGE 3 OF 11

7/27/2019 Amca 99

45/85


L length m ft

L minimum distance between louver jambs mm in.

Le equivalent length of straightener m ft

Lm average sound level from multiplexing six duct dB dB

stations or continuous circular traverses

Lmax maximum difference of microphone dB dB

readings (nose cone - sampling tube)

Lp sound pressure level re 20 Pa dB dB

pL average sound pressure level at the measuring plane dB dB

Lpmax maximum sound pressure level within the measuring duct dB dB

Lpmin minimum sound pressure level within the measuring duct dB dB

Lp1,pn corrected sound pressure level of the fan dB dB

Lp1-p6 sound pressure levels at each of six stations dB dB

in the test duct

Lpb1,pbn recorded sound pressure level of room background dB dB

as measured over the normal microphone path

Lpm1,pmn recorded sound pressure level of fan and room dB dB

background as measured over the normal

microphone path

LpNC corrected sound pressure level with nose cone dB dB

Lpq1,pqn corrected sound pressure level of reference sound source dB dB

Lpqm1,pqmn recorded sound pressure level of RSS and room dB dB

background as measured over the normalmicrophone path

LpST corrected sound pressure level with the sampling tube dB dB

Lt turbulence noise suppression value dB dB

Lw sound power level re 1x10-12

watts dB dB




60004-1893 U.S.A.


99-0070-01PAGE 4 OF 11

7/27/2019 Amca 99

46/85


LwA sound power level of fan (A-weighted; for dB dBeach band or summarized)

LWA sound power level, A-weighted, re 1x10-12

watts dB dB

LWF capacity fraction, re 1.0E-12 watts dB dB

LWG generalized sound power level, re 1.0E-12 watts dB dB

LWi sound power level at the inlet, re 1.0E-12 watts dB dB

LWiA sound power level at the inlet, A-weighted, dB dB

re 1.0E-12 watts

LW1,Wn total sound power of the test fan dB dB

LWi1,Win sound power transmitted to the inlet duct of the fan dB dB

LWK specific sound power level, re 1.0E-12 watts dB dB

LWmi measured sound power level from the inlet, dB dB

re 1.0E-12 watts

Lwmi1,wmin measured sound power at the open inlet of a fan dB dB

LWmo measured sound power level from the outlet, dB dBre 1.0E-12 watts

Lwmo1,wmon measured sound power at the open outlet of a fan dB dB

LWo sound power level at the outlet, re 1.0E-12 watts dB dB

LWoA sound power level at the outlet, A-weighted, dB dB

re 1.0E-12 watts

LWr1,Wrn sound power level rating of the reference sound source dB dB

LWo1,Won sound power transmitted to the outlet duct of the fan dB dB

Lx,x' length of duct between planes x and x' m ft

L1-5 lengths along anechoic termination m ft

l length of moment arm mm in.

la output signal of thermal mAdc mAdc

flow sensor




60004-1893 U.S.A.


99-0070-01PAGE 5 OF 11

7/27/2019 Amca 99

47/85


M Mach number --- ---

M chamber dimension m ft

M rotor mass kg ---(see W)

Mt tip speed Mach parameter --- ---

N rotational speed rev/min. rev/min.

NLA no-load amps A A

NPH nameplate power kW hp

NPV nameplate volts V V

n number of readings --- ---

P pressure Pa in. wg

P pressure differential or pressure drop across Pa in. wg

device being tested

Pc pressure drop of combined dampers Pa in. wg

PL

plane of measurement --- ---

Pn pressure differential across nozzle Pa in. wg

Pn pressure drop of damper "n" Pa in. wg

Ps static pressure or fan static pressure Pa in. wg

Ps pressure loss across damper Pa in. wg

Ps fan static pressure rise Pa in. wg

Ps static pressure regain from diffuser/evas Pa in. wg

Psx static pressure at plane x Pa in. wg

Pt total pressure or fan total pressure Pa in. wg

Pt total pressure loss due to friction Pa in. wg

Ptx total pressure at plane x Pa in. wg




60004-1893 U.S.A.


99-0070-01PAGE 6 OF 11

7/27/2019 Amca 99

48/85


Pv velocity pressure or fan velocity pr

Documents

Amca 99