1、Designation:E126504(Reapproved 2013)Standard Test Method forMeasuring Insertion Loss of Pneumatic Exhaust Silencers1This standard is issued under the fixed designation E1265;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of
2、 last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the laboratory measurement ofboth the acoustical and mechanical performance of pneumaticexhaust si
3、lencers designed for quieting compressed gas(usu-ally air)exhausts from orifices connected to pipe sizes up to34in.NPT.This test method is not applicable for exhaustsperforming useful work,such as part conveying,ejection,orcleaning.This test method evaluates acoustical performanceusing A-weighted so
4、und level measurements.1.2 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety
5、concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.Specific precau-tionary statements are given in Section 8.2.Referenced Documents2
6、.1 ASTM Standards:2C634 Terminology Relating to Building and EnvironmentalAcoustics2.2 ANSI Standards:3S1.4 Specification for Sound Level MetersS1.13 Method for the Measurement of Sound PressureLevelsS1.31 Precision Method for the Determination of SoundPower Levels of Broad-Band Noise Sources in Rev
7、erbera-tion RoomsS1.33 Engineering Methods for the Determination of SoundPower Levels of Noise Sources in a Special ReverberationRoomB2.1 Taper Pipe Thread(NPT)Standard Designation forTapered Pipe Threads2.3 Federal Standard:Rules and RegulationsHand and Portable Power Tools andEquipment43.Terminolo
8、gy3.1 DefinitionsFor definitions of terms used in this testmethod,see Terminology C634.Particular terms of interestare:sound level and average sound pressure level.3.2 Definitions of Terms Specific to This Standard:3.2.1 flow ratiothe ratio of gas flow with the pneumaticexhaust silencer installed re
9、lative to flow of the unrestrictedpipe.3.2.2 flow resistancethe reduction of fluid flow caused byvarious restrictions,surface roughness,devious paths,obstacles,etc.This term is sometimes referred to as“backpressure.”3.2.3 DiscussionFor this test method back pressure is aqualitative term,therefore,th
10、ere is no need to measure.3.2.4 insertion loss of a pneumatic exhaust silencer(at aspecificsupplypressure)thedifferenceinaverageA-weighted sound levels measured with and without thepneumatic exhaust silencer installed on an unrestricted or“open”pipe.3.2.5Discussion Insertion loss,as defined in this
11、testmethod,differs from the definition in Terminology C634.Asstated in 1.1,this test method uses A-weighting rather thandiscrete frequency bands.It compares a set of sound pressuredata measured in a reverberation room rather than determiningabsolute sound power levels.This test method is intended to
12、assess the difference in sound regenerated at the pipe orificeand does not evaluate sound propagating along the pipeinterior.1This test method is under the jurisdiction ofASTM Committee E33 on Buildingand Environmental Acoustics and is the direct responsibility of SubcommitteeE33.08 on Mechanical an
13、d Electrical System Noise.Current edition approved Feb.1,2013.Published February 2013.Originallyapproved in 1988.Last previous edition approved in 1995 as E1265 90(1995)1,which was withdrawn July 2004 and reinstated August 2004.DOI:10.1520/E1265-04R13.2For referenced ASTM standards,visit the ASTM we
14、bsite,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.an
15、si.org.4This United States Occupational Safety and Health Administration Regulation,Federal Register,Vol 36,Number 105,Part II,p.10653,May 1971,is availablefrom Superintendent of Documents,Government Printing Office,Washington,DC204029371.Copyright ASTM International,100 Barr Harbor Drive,PO Box C70
16、0,West Conshohocken,PA 19428-2959.United States1 3.2.6 pneumatic exhaust silencera device attached to apipe fitting or orifice.The silencer reduces the sound producedwhen the released pressurized exhaust gases(usually air),merge with ambient(static)air in the region surrounding theorifice.Such silencers are not usually intended to performuseful work such as part conveying,ejection,or cleaning.Theport sizes of the pneumatic exhaust silencers addressed by thistest method are:18,14,38,12,58,and34in
