ARI Standard 260-2001

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2001 Standard for

SoundRating of DuctedAir MovingAnd Conditioning

Equipment

ARI Standard 260

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Price $10.00 (M) $20.00 (NM) 8 Copyright 2001, by Air-Conditioning, Heating and Refrigeration InstitutePrinted in U.S.A. Registered United States Patent and Trademark Office

IMPORTANTSAFETY DISCLAIMER

AHRI does not set safety standards and does not certify or guarantee the safetyof anyproducts,

components or systems designed, tested, rated, installed or operated in accordance with thisstandard/guideline. It is strongly recommended that products be designed, constructed,assembled, installed and operated in accordance with nationallyrecognized safetystandards andcode requirements appropriate for products covered by this standard/guideline.

AHRI uses its best efforts to develop standards/guidelines employing state-of-the-art andaccepted industry practices. AHRI does not certify or guarantee that any tests conductedunder its standards/guidelines will be non-hazardous or free from risk.

Note:This is a new standard.

Foreword:

Ducted Equipment must be sound rated in relation to its various individual Sound Components todescribe it acoustically and to provide the necessary information for predicting application soundlevels. This standard addresses the sound rating of these various Sound Components. Ducted air-conditioning equipment can have ducted discharge, ducted inlet, free inlet (or free discharge)combined with casing radiated, or casing radiated Sound Components depending on its specificmanufactured configuration.

All Sound Components are acoustically described/rated by utilizing a "Mapped" Sound Ratingapproach that is typically referenced to the product's supply fan operating map. The supply fan iscontained in the Base Unit of the product. In addition, this standard defines an approach to accountfor and add the acoustical effects of product Appurtenances (such as modulation devices or inlet/discharge plenums) and Other Sound Sources (such as the refrigeration circuit, exhaust fans,etc.) to the Base Unit Mapped Sound Rating. Thus, Mapped Sound Ratings can be developed for agiven product configuration and each of its various Sound Components.

All ducted product Sound Components are rated utilizing a Reverberation Room Technique,modeled after AMCA Standard 300. Reverberation room tests are conducted using a ComparisonMethod and a Reference Sound Source calibrated in accordance with ARI Standard 250.

Sound ratings are in the form of Octave Band Sound Power Levels (dB) from 125 to 8,000 Hzderived from One-Third Octave Band (dB) measurements for the various product SoundComponents. Sound ratings may be provided for the 63 Hz Octave Band if the reverberation roomhas been qualified in accordance with ARI Standard 280.

A listing of current ARI Sound Standards is located in Appendix C.

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TABLE OF CONTENTS

SECTION PAGE

Section 1. Purpose ...............................................................................................................1

Section 2. Scope ..................................................................................................................1

Section 3. Definitions ..........................................................................................................1

Section 4. Requirements for Acquiring Mapped Sound Data .............................................3

Section 5. Sound Power Level Calculations and Ratings....................................................7

Section 6. Minimum Data Requirements for Published Sound Ratings .............................9

Section 7. Conformance Conditions..................................................................................10

FIGURES

Figure 1. Typical Ducted Discharge Test Setup ...............................................................5

Figure 2. Typical Ducted Inlet Test Setup ........................................................................5

Figure 3. Typical Free Inlet Combined with Casing Radiated Test Setup.........................5

Figure 4. Typical Casing Radiated Test Setup...................................................................6

Figure 5. Typical Free Inlet Test Setup..............................................................................6

APPENDICES

Appendix A. References - Normative....................................................................................11

Appendix B. References - Informative ..................................................................................12

Appendix C. ARI Standards on Sound - Informative ............................................................13

Appendix D. Atkins Sound Attenuation Adjustments for Acoustic Test DuctElbows - Normative..........................................................................................14

Appendix E. Effects of Other Sources - Normative ..............................................................15

Appendix F. Supply Fan Modulation Device Effects - Normative .......................................16

Appendix G. Method of Processing Acquired Data - Normative ..........................................17

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TABLES FOR APPENDICES

Table C1. ARI Standards on Sound - Informative ............................................................13

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ARI STANDARD 260-2001

1

SOUND RATING OF DUCTED AIR MOVING ANDCONDITIONING EQUIPMENT

Section 1. Purpose

1.1 Purpose. The purpose of this standard is to establish amethod of sound rating the indoor portions of ducted air moving and conditioning equipment and to providedefinitions; requirements for acquiring mapped sound data;Sound Power Level calculations and ratings; minimum datarequirements for published sound ratings; and conformanceconditions.

1.1.1 Intent. This standard is intended for theguidance of the industry, including manufacturers,engineers, installers, contractors and users.

1.1.2 Review and Amendment. This standard issubject to review and amendment as technologyadvances.

Section 2. Scope

2.1 Scope. This standard applies to all ducted air movingand conditioning equipment containing fans as defined inSection 3 of this standard.

Examples of such equipment when ducted are:

a. Unitary Air-Conditioners, as defined in ARIStandard 210/240 and ARI Standard 340/360

b. ARI-Source Unitary Heat Pumps, as defined inARI Standard 340/360

c. Water-Source Heat Pumps, as defined in ISO13256-1

d. Fan-Coil Air-Conditioners, as defined in ARIStandard 440

e. Central-Station Air-Handling Units, as defined inARI Standard 430

2.2 Exclusions. This standard does not apply to:

a. Air Control and Distribution Devices, which arecovered by ARI Standard 880

b. Packaged Terminal Air-Conditioners, which arecovered by ANSI/ARI Standard 300

c. Outdoor sound from outdoor portions of DuctedEquipment that would be covered under ARIStandards 270 and 370

d. The sound radiated from ductwork attached tothe fan and/or equipment when such ductwork isnot offered by the manufacturer as a standard part of the equipment

e. The casing (base pan) radiated sound

component for rooftop or down draft products

Section 3. Definitions

All terms in this document shall follow the standard industrydefinitions established in the current edition of ASHRAE Terminology of Heating, Ventilation, Air-Conditioning and Refrigeration , unless otherwise defined in this section.

3.1 Acoustic Test Duct . The duct used to convey thesound of the unit configurationunder test to the reverberationroom during a ducted discharge or the ducted inlet soundcomponent test. A Duct End Correction ( E ) must beadded tothe sound data measured in the reverberation room to accountfor the presence of an open-ended duct terminating in thereverberation room.

3.2 Acoustic Test Duct Elbow . An elbow added to theAcoustic Test Duct during a reverberation room test tofacilitate testing. An adjustment must be made (inaddition tothe Duct End Correction) to the sound data to account for the presence of the Acoustic Test Duct Elbow. Appendix D of this standard defines the Atkins sound attenuationadjustments.

3.3 Base Unit. A factory-made encased assemblyconsisting of one or more fans meant to be connected to aduct and other necessary equipment to perform one or moreof the functions of circulating, cleaning, heating, cooling,humidifying, and mixing of air, but which does not alwaysinclude a source of heating or cooling.

3.3.1 Appurtenance . An addition to a Base Unitfor purposes of control, isolation, safety, static pressure regain, wear etc.

Examples of Appurtenances include:

a. Coil(s)1. Cooling coil2. Cooling and dehumidifying coil3. Water spray (wetted coil)4. Heating coil

b. Electric heater(s)c. Air filter d. Damperse. Moisture eliminator f. Fan-motor driveg. Gas heat exchangersh. Inlet or discharge plenumsi. Modulating devices in the fan

inlet/discharge

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j. Application duct geometries (suchas duct elbow configurations)

3.4 Comparison Method. A method of determining SoundPower Level of a source under test in a reverberation roombycomparing the average Sound Pressure Level of that source tothe average Sound Pressure Level of a Reference Sound

Source of known Sound Power Level output. The differencein Sound Power Level is equal to the difference in SoundPressure Level when conditions in the room are the same for both sets of measurements.

3.5 Duct End Correction, E . Accounts for the acousticenergy in an Acoustic Test Duct that is reflectedback towardsthe source. A method for computing E is defined in 5.2.1 of this standard.

3.6 Ducted Equipment. Heating, ventilating and air-conditioning equipment having one or more supply fans. Theequipment may be configured with either:

a. Free inlet(s) with ducted discharge(s) b. Ducted inlet(s) with free discharge(s)c. Ducted inlet(s) and ducted discharge(s)

This equipment may be ducted in various configurationshorizontally and vertically, and may incorporate multipleinlets and outlets.

3.7 Effective Diameter, D. Diameter of an Acoustic TestDuct and is equal to either the diameter, ft [m], of a circular duct or the Effective Diameter, ft [m], of a rectangular duct.

D is given by the following expression:

AREA x4= D

2/1

(1)

where:

AREA = Cross-sectional area of the duct, ft 2 [m2]

3.8 Hertz (Hz). A unit of frequency equal to one cycle per second.

3.9 Low Frequency Data . Data in the 63 Hz OctaveBand(50, 63 and 80 Hz One-Third Octave Bands).

3.10 apped Sound Rating . A rating based upon tests performed across the range of operating conditions typicallydefined for the product supply fan map, in the Base Unit, andas defined by the product manufacturer. These productsinclude:

a. Belt-driven products with or without variablefrequency drives

b. Direct-drive products with variable frequencydrives

c. Direct-drive products with discrete speed taps

Note: Special case when a supply fan is used in conjunctionwith a return fan in the Base Unit (See Appendix E of thisstandard).

3.11 Octave Band . A band of sound covering a range of frequencies such that the highest is twice the lowest. TheOctave Bands used in this standard are those defined in ANSIStandard S1.11.

3.12 One-Third Octave Band . A band of sound covering arange of frequencies such that the highest frequency is thecube root of two times the lowest. The One-Third OctaveBands used in this standard are those defined in ANSIStandard S1.11.

3.13 Reference Sound Source (RSS) . A portable,

aerodynamic sound source that produces a known stable broad band sound power output.

3.14 Reverberation Room Technique . A technique used toderive the Sound Power Level of Ducted Equipment SoundComponents. The technique utilizes an Acoustic Test Ductcoupled to a reverberation room to measure the ducted inletor ducted discharge sound. Other setup configurations allowthe testing of the casing radiated or free inlet (or freedischarge) combined with the casing radiated SoundComponents. This technique is incorporated in AMCAStandard 300.

3.15"Shall" or "Should". "Shall" or "should" shall beinterpreted as follows:

3.15.1 Shall. Where "shall" or "shall not" is usedfor a provision specified, that provision is mandatoryif compliance with the standard is claimed.

3.15.2 Should. "Should" is used to indicate provisions which are not mandatory but which aredesirable as good practice.

3.16 Sound Components. The various Sound Sourcesemanating from the product that need to be independently

defined to adequately describe a products acoustic effect ona typical application.

Depending on the configuration of the equipment the SoundComponents that need to be defined consist of several or allthe following:

a. Ducted discharge b. Free inlet (or free discharge) combined with

casing radiatedc. Casing radiated

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d. Ducted inlete. Free inlet (and/or free discharge)

3.17 Sound Power Level, L w. This is ten times thelogarithm to the base ten of the ratio of the sound power radiated by the source to a reference sound power, expressedin decibels (dB). The reference sound power used in this

standard is 1 picowatt (pW).3.18 Sound Pressure Level, L p. This is twenty times thelogarithm to the base ten of the ratio of a given sound pressure to a reference sound pressure of 20 Pa, expressed indecibels (dB).

3.19 Sound Sources.

a. Base Unit . Sound generated by the supply fan(s)in the Base Unit.

b. Appurtenance . Sound generated or attenuateddue to the Appurtenance having supply fan

airflow through it.c. Other. Sound generated by an element that is notdependent on the supply fan airflow of the product. The refrigerant circuit, airborne noisefrom a variable frequency drive (VFD) ventilationfan, motor noise due to a VFD, gas burner combustion noise, and exhaust fans are examplesof Other Sound Sources.

Section 4. Requirements for AcquiringMapped Sound Data

4.1 General Overview. This standard incorporates aReverberation RoomTechnique utilizing AMCA Standard 300 toobtain the Sound Power Levels of the various SoundComponents for ducted air-moving and air-conditioningequipment. It goes beyond AMCA Standard 300 which is for rating fans, by adding the effects of Appurtenances and Other Sound Sources to the Base Unit to obtain the Mapped SoundRating of a given product configuration. Sound Power Levelsshall be obtained utilizing the Comparison Method and aReference Sound Source calibrated per ARI Standard 250. TheOne-Third Octave Band Sound Pressure Levels of SoundComponents can be measured to obtain the Sound Power Levelsrequired to rate each sound component of the equipment.

Products having multiple ducted inlets or multiple ducteddischarges on a commonface that are meant by the manufacturer to join into a common duct shall be ducted into the reverberationroom and tested at the same time. A Duct End Correctionof onlyone of the ducts shall be made. However, if products havemultiple ducted inlets or discharges on a common face or different faces, and are not joined into a common duct, each shall be ducted into the reverberation room and testedseparately. DuctEnd Corrections shall be made for each of the ducts.

The three Ducted Equipment configurations addressed by thisstandard are equipment with:

a. Free inlet(s) with ducted discharge(s) b. Ducted inlet(s) with free discharge(s)c. Ducted inlet(s) and ducted discharge(s)

The threeequipment configurations have thefollowingSoundComponents:

4.1.1 Equipment with Free Inlet(s) and Ducted Discharge(s). The following Sound Power Levelsshall be determined for this configuration:

a. Free inlet combined with casingradiated b. Ducted dischargec. Free inlet

Note: The free inlet combined with casing radiatedsound power component shall not be derived from

separate free inlet and casing radiated sound tests.4.1.2 Equipment with Ducted Inlet(s) and Free Discharge(s). The following Sound Power Levels can be determined for this configuration:

a. Ducted inlet b. Casing radiated combined with free

dischargec. Free discharge

Note: The free discharge combined with casingradiated sound power component shall not be derived

from separate free dischargeandcasingradiated soundtests.

4.1.3 Equipment with Ducted Inlet(s) and Ducted Discharge(s). The following Sound Power Levels can be determined for this configuration:

a. Ducted inlet b. Casing radiatedc. Ducted discharge

4.2 Testing Considerations. All Ducted Equipment isacoustically described by conducting Mapped Sound Rating

tests. Mapped Sound Ratings for each Sound Component of a product are obtained by first mapping the supply fan in theBase Unit. The Appurtenance and Other Sound Sources areadded as necessary to a supply fan sound map of the BaseUnit.

4.2.1 Base Unit. A sufficient number of speedcurves and test points along each speed curve shall beevaluated to ensure that the difference betweenadjacent test points does not exceed 5 dB for anygiven One-Third Octave Band. At a minimum, Base

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Units shall be tested along the highest and lowestspeed curves across the full operational map asspecified by the manufacturer.

4.2.2 Appurtenances. A sufficient number of testdata points shall be evaluated to ensure that theacoustical effect of the Appurtenanceon the Base Unit

is understood. The objective of the test is to determineif the Appurtenance canbe represented byanaveragedacoustical effect or if it must be described as afunction of airflow velocity.

4.2.2.1 echanical Airflow Control Device. The effects of a mechanical airflowcontrol device (excluding variable frequencydrives) shall be defined as outlined in AMCAStandard 300 (Appendix G).

4.2.3 Other Sources. A sufficient number of operating conditions shall be evaluated to ensure that

the acoustical effects of the Other Sound Sources onthe Base Units are understood.

4.2.3.1 Refrigerant Circuit Sources.Refrigerant circuit related sources areidentified and defined only in reference to theARI thermal rating standard operation pointfor a given product (see Appendix E).

4.2.3.2 Exhaust and Return Fans. Theeffects of the exhaust and return fan SoundSource shall be evaluated at a nominal static pressure and airflow specified by the

manufacturer (see Appendix E).4.2.3.3 Burners. The effects of the burner Sound Source shall be evaluated atthe input rate and gas type specified on thenameplate.

4.3 ethod of Test. All sound tests shall be conductedutilizing a Reverberation Room Technique modeled after AMCA Standard 300. However, the specific test setup willdepend on the product Sound Components being tested.

4.3.1 Ducted Sound Components. For ducted inlet

and ducted discharge components tested in accordancewith AMCA Standard 300 (Section 5), the Duct EndCorrection ( E ) must be added to each One-ThirdOctave Band for all products. The addition of theDuct End Correction ( E ) provides the user with thesound power that would be transmitted into a non-reflecting duct system.

Although a straight Acoustic Test Duct is preferred for ducted component tests, an Acoustic Test Duct Elbowmay be used to accommodate test facility issues. If an

Acoustic Test Duct Elbow is employed, adjustmentsshall be added to the sound data to account for attenuation of the Acoustic Test Duct Elbow using theAtkins adjustments as given in Appendix D.

4.3.1.1 Orifice End Plate. The orificeend plate, as described in AMCA Standard

300 (Appendix C, SectionC2), shall not beused to control the Acoustic Test Ductairflow in this standard.

4.3.2 Casing Radiated Combined with a Free Inlet or Free Discharge. All casing radiated with free inletor free discharge Sound Components shall be tested per AMCA Standard 300 (Section 5).

4.3.3 Casing Radiated Sound. For the casingradiated Sound Component, AMCA Standard 300(Appendix G) shall be used to determine the SoundPower Level.

4.4 Test Equipment and Facilities.

4.4.1 Reverberation Room Instrumentation. Thereverberation room instrumentation shall meet or exceed ANSI Standard S12.31, Section 4.

4.4.2 Reverberation Room Qualification. Thereverberationroom used in testing shall be qualified inaccordance with ANSI Standards S12.31 and S12.32using frequency rather than noise source position asthe independent variable (and ARI Standard 280 if lowfrequency Sound Power Levels are to be determined).

4.4.3 Reference Sound Source (RSS) . TheReference Sound Source shall be calibrated inaccordance with ARI Standard 250.

4.4.4 Equipment Size. For reverberation roomtesting, the total equipment volume, includingductwork, shall not exceed 5 % of the volume of thereverberation room.

4.4.5 Use of Windscreen. During testing, a foam ball windscreen may be used on the microphone. Theeffect of the windscreen on the microphone response

shall not be more than + 1 dB for frequencies of100 to4,000 Hz or + 1.5 dB for frequencies from 4,000 to10,000 Hz. Sound measurements shall not be madewith air velocities over the microphone exceeding1,056 ft/min [5.4 m/s].

4.4.6 Airflow Limitation. For sound testmeasurements made within a test room in accordancewith AMCA Standard 300, it is recommended that theairflow of the test unit, in cfm [m 3/min], shall notexceed, numerically, the room volume in ft 3 [m3].

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4.4.7 Test Unit Airflow Measurements. All testairflow measurements shall be made in accordancewith ANSI/AMCA Standard 210.

4.5 General Test Setup

4.5.1 Ducted Discharge Tests . For this test the unit

discharge is ducted into the reverberation room usingan Acoustic Test Duct. The sound power of theducted discharge shall be determined using AMCAStandard 300 (Section 5, Figure 3). The testconfiguration will typically be as shown in Figure 1.For ducted discharge tests, it is recommended that theAcoustic Test Duct be three effective duct diameters inlength, but not less than 3.0 ft [0.91 m]. However,duct lengths up to five effective duct diameters are permissible if needed for setup or airflowperformancemeasurements.

Figure 1. Typical Ducted Discharge TestSetup

4.5.2 Ducted Inlet Tests . For this test the unit inletis ducted into the reverberation room using anAcoustic Test Duct. The sound power of the ductedinlet shall be determined using AMCA Standard 300(Section 5, Figure 2). The test configuration willtypically be as shown in Figure 2. For ducted inlettests, it is recommended that the Acoustic Test Duct beone effective duct diameter in length, but not less than

3.0 ft [0.91 m]. However, duct lengths up to fiveeffective duct diameters are permissible if needed for setup or airflow performance measurements.

Figure 2. Typical Ducted Inlet Test Setup

4.5.3 Free Inlet (or Free Discharge) Combined with Casing Radiated Test. For this test, the unitdischarge (the inlet) is ducted outside of thereverberation room. The discharge is ducted through a

hole in the reverberation room wall, with the ducteffectively lagged to prevent sound breakout into thereverberationroom. The sound power of the free inlet(or discharge) combined with casing radiated soundshall be determined using AMCA Standard 300(Section 5, Figure 2 for inlet and Figure 3 for discharge). The test configuration will typically be asshown in Figure 3.

Figure 3. Typical Free Inlet Combined withCasing Radiated Test Setup

4.5.4 Casing Radiated Test. The casing of the unitmust be in the reverberation room with both the inletand the discharge ducted out of the test space. Theattached ductwork must be effectively lagged to prevent significant duct sound radiation. The sound power shall be determined using AMCA Standard 300(Appendix G). The test configuration will typicallybeas shown in Figure 4.

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Figure 4. Typical Casing Radiated TestSetup

4.5.5 Free Inlet or Free Discharge. For this test,the free inlet or free discharge of the unit must be

connected through a hole in the reverberation roomwall with the minimum amount of duct required to provide a proper seal. The Sound Power Level shallthen be determined using AMCA Standard 300(Section 5). The test configuration for free inlet willtypically be as shown in Figure 5.

Figure 5. Typical Free Inlet Test Setup

4.5.6 Ductwork Required for Testing. Ductwork attached to the unit under test may influence the soundmeasured. Thus, care should be taken in theattachment and treatment of all ductwork.

4.5.6.1 Ductwork Size. Ductwork shall be sized to match the manufacturer'srecommended supply or return opening andshall maintain a constant cross section.

If the manufacturer does not define thesupply or return opening, it is recommendedthat the Acoustic Test Duct be sized for amaximum of 2000 ft/min [10.2 m/s]. Theratio of the longer to the shorter sides of therectangular duct cross section shall notexceed four unless this is not possible due to

the manufacturers specifications.4.5.6.2 Ductwork Connection. Ductwork shall be connected to the unit under test usinga flexible connector. All flexible ductconnectors shall be appropriately treated toretain flexibility and to contain the soundwithin the duct.

4.5.6.3 Construction of Test Ductwork.Ductwork used in the determination of ducted inlet and ducted discharge sound power shall be of a high transmission loss

construction. The ductwork shall beconstructed, at a minimum, of either:

a. 18-gauge sheet metalstiffened by a in thicknessgypsum board attached by sheetmetal screws (on 6 in centers)and adhesive to the exterior of the duct, or

b. Round sheet metal or PVCduct with a 1 lb/ft 2 limp exterior acoustical barrier, or

c. in plywood. For highaspect ratio ducts it may also benecessary to stiffen the in plywood.

4.5.7 Duct Static Pressure Taps. Shall be per ASHRAE Standard 37 (Section 6).

4.5.8 Acoustic Test Ducts and Acoustic Test Duct Elbow. For testing of ducted inlet or discharge,straight Acoustic Test Ducts are recommended.However, the standard allows for the use of an

Acoustic Test Duct Elbow due to facility issues. Theuse of an Acoustic Test Duct Elbow, its description,and the adjustments applied must be stated. If elbowsare needed, the adjustments given by Atkins must beused (see Appendix D).

4.5.9 Acoustic Duct Flow Considerations. It isrecommended that the Acoustic Test Duct be sized for a maximum of 2000 ft/min [10.2 m/s], unless this isnot possible due to the manufacturers specifications.

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4.6 Data Acquisition. For each of the mapped operating points defined by measurements made in accordance withANSI/AMCA Standard 210, measure thecorresponding One-Third Octave Band Sound Pressure Levels. These SoundPressure Levels shall be measured for the desired SoundComponents for the Base Unit, Appurtenances, and Other Sound Sources over the mapped operating range in

accordance with the appropriate sections of AMCA Standard300 and this standard.

4.6.1 Information to be Recorded. The followingshall be compiled and recorded for measurements thatare made according to the requirements of thisStandard. The following is a list of data required todocument the noise ratings supplied per this standard:

a. Description of unit under test b. One-Third Octave Band Sound Power

Levels with Duct End Corrections (if applicable) included, dB

c. One-Third Octave Band Duct EndCorrections, dB, and description of howduct was terminated in the reverberationroom

d. Duct internal height, width, and lengthdimensions, ft [m]

e. Acoustic Test Duct ElbowOctave Bandcorrection (if used)

f. Acoustic Test Duct Elbow internalheight, width and length dimensions (if used), ft [m]

g. Description of thermal conditions duringtest

h. Airflow, cfm [m3

/s], duct static pressure, in H 2O [kPa], fan speed, rpm[rev/s], fan motor BHP for each test point

i. Sound component measured j. Test datek. Facility used

4.6.1.1 Unit Under Test.

a. Description of Base Unitshall include information toclearly identify the unit

under test such as fan typeand size, cabinet wallconstruction and size, motor manufacturer and size

b. Operating conditions (fanspeed, rpm [rev/s], airflowcfm [m 3/s], fan static pressure, in H 2O [kPa], andair density, lb/ft 3 [kg/m 3])

c. Installation/mounting detailsd. Description of

Appurtenancese. Description ofOther Sourcesf. Acoustic Test Duct

dimensions, ft [m]g. Acoustic Test Duct Elbow

dimensions, ft [m]4.6.2 Thermal Conditions During Test.

a. Air temperature, oF [oC] b. Relative humidity, %c. Barometric pressure, in Hg [kPa]

4.6.3 Instrumentation.

a. The equipment used for themeasurements, including name, type,serial number and manufacturer

b. Description of Reference Sound Sourceused

Section 5. Sound Power Level Calculationsand Ratings

5.1 General. This standard utilizes an Octave Band SoundPower Level rating system based on One-Third Octave BandSound Pressure Level test data. The procedure for obtainingthe Octave Band power level rating depends on the SoundComponent being considered. Non-ducted SoundComponents (casing radiated, free inlet combined with casing

radiated, and free components) are obtained directly from theSound Pressure Level data by utilizing Equation 2 in 5.2.Ducted Sound Components (ducted dischargeor ducted inlet)must include Duct End Corrections and effects of theAcoustic Test Duct Elbow, if used during the sound test. Aflow chart of how the data is processed for these twocategories of Sound Components is presented in Appendix G.

5.2 ethod of Processing Acquired Data. All of themeasured One-Third Octave Band Sound Pressure Level dataacquired in Section4 shall be converted to One-Third OctaveBand Sound PowerLevels using Equation 2. Adjustments for Duct End Correction ( E ), as outlined in 5.2.1 and 5.2.2, shall

be added to the calculated One-Third Octave Band SoundPower Levels when required for ducted Sound Components.

Lw(n) = L p(n) + [ Lwr(n) L pr(n) ] + E(n) (2)

where:

Lw(n) = Test unit Sound Power Level, dB, in the nh

One-Third Octave Band L p(n) = Test unit measured Sound Pressure Level, dB,

in the n h One-Third Octave Band

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Lwr(n) = RSS Sound Power Level, dB, in the nh One-

Third Octave Band L pr(n) = RSS measured Sound Pressure Level, dB, in the

n h One-Third Octave Band E(n) = Duct End Correction, dB, in the n h One-Third

Octave Band when required

Note: the Sound Pressure Levels of L p(n) and L pr(n) shall becorrected for ambient intrusion per AMCA Standard 300(Section 6.2.1).

5.2.1 Calculation of the Duct End Correction (E) .For ducted inlet or discharge elements that are testedin accordance with this standard, the Duct EndCorrection ( E ) must be added to each One-ThirdOctave Band Sound Power Level. The addition of theDuct End Correction ( E ) to the tested Sound Power Levels will provide the user with the sound power thatwould be transmitted into a non-reflecting duct system.Additionally, Duct End Correction values in Octave

Bands shall be calculated as shown in 5.5 for inclusionas part of a units ducted ratings.

For a ducted inlet or discharge, the value for the DuctEnd Correction ( E ) can be expressed by the followingtwo equations (from ASHRAE Algorithms for HVAC Acoustics ), one for an Acoustic Test Duct penetratinginto the free space of the reverberant room and theother for an Acoustic Test Duct terminating flush withthe reverberant room wall (Equations (3) and (4)respectively). These expressions shall be used tocalculate the correction ( E ) at the center frequenciesof each One-Third Octave or Octave Band.

For a duct terminating at a distance greater than or equal to D from the reverberation room wall, use thefollowing equation:

) D f

C +(110= E o1.88

10

log (3)

where:

f = One-Third Octave Band center frequency,(Hz)

C o = Speed of sound in air, ft/s [m/s]

D = Diameter, ft [m] of a circular duct or theEffective Diameter of a rectangular duct(as shown in Equation 1)

For a duct terminating flush or at a distance less than D from the reverberation room wall, use thefollowing equation:

) DC 0.8+(110= E o

1.88

10

log (4)

5.2.2 Duct End Correction Limit . When using theequation for Duct End Corrections in 5.2.1, themaximum value for E shall not exceed 14 dB.

Note: It should be understood that the Duct EndCorrections become numerically large for productswith small effective duct diameters. This may tend to

overstate the Sound Power Levels at low frequenciesfor such small products. For this reason, sufficientinformation is to be presented with the sound ratingdata to allow informed users of this information toidentify the value of E for a specific unit ductedcomponent.

5.3 Determination of Equipment Octave Band Sound Power Levels. One-Third Octave Band Sound Power Levelsof Ducted Equipment can be determined for various productSound Components (ducted discharge, ducted inlet, casingradiated, and free inlet combined with casing radiated).These One-Third Octave Band Sound Power Levels shall be

converted to Octave Band Sound Power Levels for the purposes of rating the equipment. Adjustments as outlined in5.3.2 shall be added to the calculated Octave Band SoundPower Levels when required.

5.3.1 Converting One-Third Octave Sound Power Levels to Octave Sound Power Levels. EquipmentSound Power Levels for each One-Third OctaveBandshall be determined from Sound Pressure Level dataacquired in accordance with Section 4.

The three One-Third Octave Band Sound Power Levels whose frequencies fall within the Octave Band

are summed as:

(5)

where:

Lwo(n) = Sound Power Level in the nh

Octave Band, dB Lw(n) = Sound Power Level in the n

h

One-Third Octave Band, dBn = One-Third Octave Band of

interest in the Octave Band

Each Octave Band Sound Power Level shall berounded to the nearest decibel.

5.3.2 ethod for Processing Data When Using an Acoustic Test Duct with an Acoustic Test Duct Elbow.If it is necessary to use an Acoustic Test Duct Elbow,the computed Octave Band Sound Power Levels shall be adjusted by adding the Atkins adjustments given inAppendix D to each Octave Band.

( ) ][log 1010= L10

L w(n)3=n

1=n10nwo

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5.4 apped Sound Ratings To Be Presented. TheMapped Sound Ratings shall be published, printedor providedin a selection program.

5.4.1 Base Unit Supply Fan Rating. This ratingshall be considered representative of the total unitoperation sound if Appurtenance and Other Sound

Source effects are shownnot to contribute to the soundcomponent under test.

5.4.2 Appurtenance Ratings. Sound ratings foranyAppurtenance effect upon the Base Unit must be basedon data as specified in Section 4. A description of theAppurtenance and a description of all significant testdetails must be presented with the sound data.

5.4.3 Other Sound Source Ratings. Sound ratingsfor any Other Sound Source must be added to the BaseUnit and anyAppurtenance effects. The sound ratingsare to be based on data as specified in Section 4. A

description of all significant test details must be presented with the sound data.

5.4.4 Predicted Sound Ratings for Untested FanOperating Points and Unit Sizes. With certainrestrictions, sound ratings can be predicted for untested fan operating points and unit sizes.

5.4.4.1 Sound Estimation for Untested Fan Operating Points. The manufacturer may estimate Sound Power Levels and provide ratings for other supply fan operating points using an appropriate algorithm that is

based on the Sound PowerLevels determined by testing over the operational map.However, Sound Power Levels and ratingsshall not be estimated for supply fanoperating points where operational speeds,rpm[rev/s], static pressure, in H 2O [kPa] andhorsepower are greater than or less than thehighest or lowest operational speed, rpm[rev/s], static pressure, in H 2O [kPa] andhorsepower tested.

5.4.4.2 Estimated Ratings for Untested Product Sizes or Appurtenances . Tested

product data may be used to estimate theSound Power Levels and ratings of anuntested size of the same product line as longas:

a. The fans are of the samegeometric family

b. The cabinet size,Appurtenances, or geometricscaling from one product sizeto another does not invalidate

scaling laws based on thefansimilarities

c. The sound levels of the twounit sizes tested and used for interpolation do not differ bymore than 5 dB

Note: It shall be up to the manufacturer totest a sufficient number of product sizes in agiven product line to assure an accuratemethod of prediction.

5.5 Determination of Octave Band Duct End Correction Levels for Ratings. Octave Band Duct End Correction levelsshall be published with ducted discharge and/or ducted inletrating(s).

5.5.1 Procedure forCalculatingOctave Band Duct End Correction levels. Using the methodology of Equation (5) to calculate Octave Band levels of both

the test unit One-Third Octave Sound Power Levelswith the Duct End Correction levels added and the testunit One-Third Octave Sound Power Levels withoutDuct End Correction added, the difference in theseoctave levels are the Duct End Correction levels.

E o(n) = Lwc(n) Lw(n) (6)

where:

E o(n) = Duct End Correction, dB, for nh

Octave Band Lwc(n) = Octave Band Sound Power Level, dB,

with Duct End Correction applied for nh

Octave Band Lw(n) = Octave Band Sound Power Level, dB,

for n h Octave Band without Duct EndCorrection applied

Note: Value shall not exceed level set in 5.2.2.

Section 6. Minimum Data Requirements for Published Sound Ratings

6.1 inimum Data to be Included in Published Sound

Ratings. The following is a list of data required to documentthe ducted noise ratings supplied per this standard:

a. Unit configuration, Base Unit,Appurtenances and other sources

b. Octave Band Sound Power Levels, dBc. Octave Band Duct End Corrections, dB (see

AMCA Standard 300, Appendix C.9) and howduct was terminated in the reverberation room

d. Duct internal height, width and lengthdimensions, ft [m]

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e. Acoustic Test Duct Elbow Octave Bandcorrection (if used)

f. Acoustic Test Duct Elbow internal height andwidth dimensions (if used), ft [m]

g. Fan speed, rpm [rev/s], fan static pressure, inH2O [kPa], and fan motor BHP for each test point

h. Component under test, supply, return or casingradiated

Note: The Octave Band data shall be rounded to the nearestdecibel.

6.2 Verification of Published Sound Ratings . Anyequipment selected at random and tested in a suitablyqualified laboratory in accordance with this standard shallhave a sound rating not higher than itspublished sound rating.

Section 7. Conformance Conditions

7.1 Conformance. While conformance with this standardis voluntary, conformance shall not be claimed or impliedfor products or equipment within its Purpose (Section 1) andScope (Section 2) unless such claims meet all of therequirements of the standard.

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APPENDIX A. REFERENCES - NORMATIVEA1 Listed here are all standards, handbooks, and other publications essential to the formation and implementationof the standard. All references in this appendix areconsidered as part of this standard.

A1.1 AMCA Standard 300-96, Reverberant Room Method for Sound Testing of Fans , 1996Air Movement And Control Association, 30West University Drive, Arlington Heights, IL,60004-1893, U.S.A.

A1.2 ANSI/AMCA Standard 210-99, Laboratory Methods of Testing Fans for aerodynamic performance Rating , 1999,American National Standards Institute/Air Movement And Control Association, 11 West42 d Street, New York, NY 10036 U.S.A./30West University Drive, Arlington Heights, IL,60004-1893, U.S.A.

A1.3 ANSI Standard S1.11-1986 (R1996) ,Specifications for Octave -Band and Fractional Octave-Band Analog and Digital Filters , 1993,American National Standards Institute, 1986, 11West 42nd Street, New York, NY, 10036,U.S.A.

A1.4 ANSI Standard S12.31-1990 (R1996), Precision Methods for the Determination of Sound Power Levels of Broad-Band Noise sources in Reverberation Rooms, 1996,American National Standards Institute, 11 West42 d Street, New York, NY 10036, U.S.A.

A1.5 ANSI Standard S12.32-1990 (R1996), Precision Methods for the Determination of Sound Power Levels of Discrete-Frequency and Narrow-Band Noise Sources in Reverberation Rooms , 1996, American National StandardsInstitute, 1990, 11 West 42nd Street, NewYork, NY, 10036, U.S.A.

A1.6 ARI Standard 210/240-94, Unitary Air Conditioning and Air-Source Heat Pump Equipment, 1994, Air-Conditioning andRefrigeration Institute, 4301 North FairfaxDrive, Suite 425, Arlington, VA, 22203, U.S.A.

A1.7 ARI Standard 250-2001, Performance And Calibration Of Reference Sound Sources2001, Air-Conditioning and RefrigerationInstitute, 4301 North Fairfax Drive, Suite 425,Arlington, VA, 22203, U.S.A.

A1.8 ARIStandard 280-95, Requirementsfor the Qualification of Reverberant Rooms in the63 Hz Octave Band , 1995, Air-ConditioningandRefrigeration Institute, 1995, 4301North FairfaxDrive, Suite 425, Arlington, VA, 22203, U.S.A.

A1.9 ARI Standard 340/360-2000, Commercial and Unitary Air-Conditioning and Heat Pump Equipment , 2000, Air-Conditioningand RefrigerationInstitute, 4301 North Fairfax Drive, Suite 425,Arlington, VA, 22203, U.S.A.

A1.10 ARI Standard 430-99, Central-Station Air- Handling Units, 1999, Air-Conditioning andRefrigeration Institute, 4301 North Fairfax Drive,Suite 425, Arlington, VA, 22203, U.S.A.

A1.11 ARI Standard 440-98, Room Fan-Coils and Unit Ventilators, 1998, Air-Conditioning andRefrigeration Institute, 1997, 4301 North FairfaxDrive, Suite 425, Arlington, VA, 22203, U.S.A.

A1.12 ASHRAE - Algorithms for HVAC Acoustics ,1989, American Society of Heating, Refrigeratingand Air-Conditioning Engineers, 1791 Tullie Circle NE, Atlanta, GA, 30329-2305, U.S.A.

A1.13 ASHRAE Terminology of Heating,Ventilating, Air-Conditioning and Refrigeration,Second Edition, 1991, American Society of Heating,Refrigeration, and Air-Conditioning Engineers, Inc.,1791 Tullie Circle, NE Atlanta, GA. 30329. U.S.A.

A1.14 ASHRAE Standard 37 , Methods of Testing for Rating Unitary Air Conditioning and Heat Pump Equipment, 1998, American Society of Heating,Refrigeration, and Air-Conditioning Engineers, Inc.,1791 Tullie Circle, NE Atlanta, GA 30329. U.S.A.

A1.15 Iqbal, M.A., Willson, T.K., Thomas, R.J.The Control of Noise in Ventilation Systems: adesigners guide, 1977, E.& F.N. SponLtd,11NewFetter Lane, London EC4P 4EE, Great Britain

A1.16 ISO 13256-1: 1998, Water-source heat pumps Testing and Rating for Performance Part 1: Water-to-Air and Brine-to-Air Heat Pumps, 1998,International Organization for Standardization, CasePostale 56, CH-1211, Geneva 21 Switzerland.

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APPENDIX B. REFERENCES - INFORMATIVE

B1 Listed here are standards, handbooks and other publications which may provide useful information and background but are not considered essential. References inthis appendix are not considered part of the standard.

B1.1 ANSI/ARI Standard 300-2000, Sound Rating and Sound Transmission Loss of Packaged Terminal Equipment , 2000, American National StandardsInstitute/Air-Conditioning and Refrigeration Institute,11 West 42nd Street, New York, NY, 10036, U.S.A.4301 North Fairfax Drive, Suite 425, Arlington, VA,22203, U.S.A.

B1.2 ARI Standard 310/380-93, Packaged Terminal Air-Conditioners and Heat Pumps , 1993,Air-Conditioning and Refrigeration Institute, 4301 North Fairfax Drive, Suite 425, Arlington, VA, 22203,U.S.A. (CSA-C744-93) (ANSI/ARI 310/380-93).

B1.3 ARI Standard 880-98, Air Terminals, 1998,Air-Conditioning and Refrigeration Institute, 4301 North Fairfax Drive, Suite 425, Arlington, VA, 22203,U.S.A.

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APPENDIX C. ARI STANDARDS ON SOUND - INFORMATIVEC1. Purpose.

Table C1 following lists current ARI Sound Standards.

TABLE C1. ARI STANDARDS ON SOUND

ARI SOUNDSTANDARD

TITLE EQUIPMENT COVERED REFERENCETEST

METHODS250 Performance And Calibration of

Reference Sound SourcesReference Sound Sources

260 Sound Rating of Ducted Air Moving and ConditioningEquipment

Ducted air-conditioning equipment containing fans AMCA 300-96;ANSI S12.32-90 (R1995)

270 Sound Rating of Outdoor UnitaryEquipment

Unitary air-conditioners and heat pumps under 135,000 Btu/h

ANSI S12.32-90 (R1995);

ISO 3742-1988275 Application of Sound RatedOutdoor Unitary Equipment

Same as 270-95 ARI 270-95

280 Requirements for the Qualificationof Reverberant Rooms in the 63Hz Octave Band

Reverberant Rooms

300 Sound Rating and SoundTransmission Loss of PackagedTerminal Equipment

Packaged terminal air-conditioners and packagedterminal heat pumps

ANSI S12.32(1995);ASTM E90 1990

350 Sound Rating of Non-DuctedIndoor Air-Conditioning

Equipment

1) Unitary equipment(unlimited size)

2) Packaged terminalequipment

3) Water-source and groundwater-source heat pumps

ANSI S12.32-90 (R1995)

370 Sound Rating of Large Outdoor Refrigerating and Air-Conditioning Equipment

All outdoor ARI-type equipment not covered by ARIStandard 270-95

ANSI S12.32-90 (R1995);ISO 3745-1977

530 Method of Measuring Sound andVibration of RefrigerantCompressors

External drive and hermetic-type compressors ANSI S12.32(1995);ISO 3745-1977

575 Methods of Measuring MachinerySound Within Equipment Rooms

Complete water-chilling systems located in a definedspace

None

880 Air Terminals Ducted air control and distribution devices notincluding the central station fan(s)

ANSI S12.31-90

885 Procedure for EstimatingOccupied Space Sound Levels inthe Application of Air Terminalsand Air Outlets

Ducted air control distribution devices not includingthe fan(s)

ARI 880-98

890 Rating of Air Diffusers and Air Diffuser Assemblies

Ducted diffuser and diffuser assemblies connected toremote forced air source

ARI 890-94

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APPENDIX D. ATKINS SOUND ATTENUATION ADJUSTMENTSFOR ACOUSTIC TEST DUCT ELBOWS 1 - NORMATIVE

1 Reference: Iqbal, M.A., Willson, T.K., Thomas, R.J. The Control of Noise in Ventilation Systems: a designers guide,1977, E. & F. N. Spon Ltd, 11 New Fetter Lane, London EC4P 4EE, Great Britain

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APPENDIX F. SUPPLY FAN MODULATION DEVICE EFFECTS -NORMATIVE

F1 odulation Device Insertion Effects . This testidentifies the acoustic effects of inserting a modulationdevice (such as inlet guide vanes at the fully open position)

in the fan airflow. It does not measure the effects of actualmodulation. Testing is conducted with the modulationdevice fully open (for guide vanes fully open) across theentire supply fan map.

F2 odulation Device Modulation Effects . This test provides representative modulated system curves for the product with a mechanical modulation device. This test isdefined for various percentages of modulation of amodulation device along the same system curve as definedfor the insertion effect. It can be conducted for twoadditional system curves, if desired.

Modulation device insertion effects shall first have beendefined, at a minimum, along a single constant systemcurve.The initial point of the system curve shall be on the highest

fan speed curve with the test point (static and airflow) beingmid-way between stall and full open flow. Tests shall beconducted at this point with the modulation device fullyopen. Additional points along the system curve are obtained by operating the supply fan at other speeds defined in theoriginal supply fan map with the modulation device atvarious degrees of closure. Additional tests areconducted at, , , and fully close guide vane settings, applying thesame system load line. Additional system lines may betested, starting at a test point along the highest speed curvenearest the maximum efficiency point and at a more wideopen point as defined by the manufacturer, if desired.

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APPENDIX G. METHOD OF PROCESSING ACQUIREDDATA NORMATIVE

Note: Sections refer to ARI Standard 260.

One- hird Octave BandSound Pressure TestData. (Sec 4)

Convert One-Third Octave BandSound Pressure to One-ThirdOctave Band Sound Power (Sec5.2

Convert One-Third Octave BandSound Power to Octave BandSound Power Sec 5.3 & 5.3.1

Published Octave Band SoundPower Ratings for Non Duct SoundComponents (Sec 6.1)

DuctedComponent

No

Yes

Convert One-Third Octave BandSound Power to Octave BandSound Power Sec 5.3 & 5.3.1

TestDuctElbow

Yes

No

Calculate Duct End Correction for Each One-Third Octave Band (Sec5.2.1 & 5.2.2

Add Duct End Correction to EachOne-Third Octave Band (Sec 5.2)

Subtract Octave Band Sound Power ith Duct End Correction Octave

Band Sound Power Without DuctEnd Correction (Sec 5.5)

Published Octave Band Duct EndCorrection Data (Sec 6.1)

Add Elbow Correction to EachOctave Band (Sec 5.3.2)

Published Octave Band Sound Power Ratings for Ducted Component (Sec6.1)

Yes TestDuctElbow

Add Elbow Correction to Each OctaveBand (Sec 5.3.2)

No

Convert One-Third Octave BandSoundPower to Octave Band Sound Power (Sec 5.3 & 5.3.1)

ARI Standard 260-2001

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