1、Designation: C522 03 (Reapproved 2009)1Standard Test Method forAirflow Resistance of Acoustical Materials1This standard is issued under the fixed designation C522; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re
2、vision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTESection 1.4.1 was editorially added in March 2010.1. Scope1.1 This test method covers the measurement of airflowresistance and the r
3、elated measurements of specific airflowresistance and airflow resistivity of porous materials that can beused for the absorption and attenuation of sound. Materialscover a range from thick boards or blankets to thin mats,fabrics, papers, and screens. When the material is anisotropic,provision is mad
4、e for measurements along different axes of thespecimen.1.2 This test method is designed for the measurement ofvalues of specific airflow resistance ranging from 100 to10 000 mks rayls (Pas/m) with linear airflow velocities rang-ing from 0.5 to 50 mm/s and pressure differences across thespecimen rang
5、ing from 0.1 to 250 Pa. The upper limit of thisrange of linear airflow velocities is a point at which the airflowthrough most porous materials is in partial or completetransition from laminar to turbulent flow.1.3 A procedure for accrediting a laboratory for the pur-poses of this test method is give
6、n in Annex A1.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4.1 Table 1 is provided for user to convert into cgs units.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its
7、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.2. Referenced Documents2.1 ASTM Standards:2E384 Test Method for Knoop and Vickers Hardness ofMaterialsC634 Terminolo
8、gy Relating to Building and EnvironmentalAcousticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions: The definitions used in this test method arecontained in Terminology C634.3.2 Definitions of Terms Specific to This Standar
9、d: Thefollowing items have been modified to exclude alternatingflow.3.2.1 airflow resistance, R; mks acoustic ohm(Pas/m3)the quotient of the air pressure difference across aspecimen divided by the volume velocity of airflow through thespecimen.3.2.2 airflow resistivity, r0; mks rayl/m (Pas/m2) of ah
10、omogeneous material, the quotient of its specific airflowresistance divided by its thickness.3.2.3 lateral airflow resistivity of an anisotropic homoge-neous material, the airflow resistivity when the direction ofairflow is parallel to the face of the material from which the testspecimen is taken.3.
11、2.4 specific airflow resistance, r; mks rayl (Pas/m)theproduct of the airflow resistance of a specimen and its area.This is equivalent to the air pressure difference across thespecimen divided by the linear velocity of airflow measuredoutside the specimen.3.2.5 transverse airflow resistivity of an a
12、nisotropic ho-mogeneous material, the airflow resistivity when the directionof airflow is perpendicular to the face of the material fromwhich the test specimen is taken.3.3 Application of Terms:3.3.1 The term airflow resistance can be applied to speci-mens of any kind.1This test method is under the
13、jurisdiction ofASTM Committee E33 on Buildingand Environmental Acoustics and is the direct responsibility of SubcommitteeE33.01 on Sound Absorption.Current edition approved Oct. 1, 2009. Published February 2010. Originallyapproved in 1963. Last previous edition approved in 2003 as C522 03. DOI:10.15
14、20/C0522-03R09.2For referenced ASTM standards, visit the ASTM website, 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.TABLE 1 Conversion from cgs to mks and SI unit
15、sTo convert from to Multiply bycgs acoustic ohm mks acoustic ohm (Pas/m3)105cgs rayl mks rayl (Pas/m) 10cgs rayl/cm mks rayl/m (Pas/m2)103cgs rayl/in. mks rayl/m (Pas/m2) 394mks rayl/in. mks rayl/m (Pas/m2) 39.41Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
16、19428-2959, United States.3.3.2 The term specific airflow resistance has meaning onlywhen applied to a specimen of uniform thickness that ishomogeneous in directions parallel to its surface but notnecessarily homogeneous in the direction of airflow perpen-dicular to its surface.3.3.3 The term airflo
17、w resistivity has meaning only whenapplied to a specimen that is homogeneous in directionsparallel to a and perpendicular to its surface but not necessarilyisotropic.3.4 Symbols:3.4.1 P = air pressure difference across test specimen, Pa.3.4.2 U = volume velocity of airflow through the specimen,m3/s.
18、3.4.3 u = U/S = linear velocity of airflow outside thespecimen, m/s.3.4.4 S = area of specimen, m.23.4.5 T = thickness of specimen, m.4. Summary of Test Method4.1 This test method describes how to measure a steady flowof air through a test specimen, how to measure the air pressuredifference across t
19、he specimen, and how to measure thevolume velocity of airflow through the specimen. From themeasurements may be calculated the airflow resistance, R, thespecific airflow resistance, r, and the airflow resistivity, r0.5. Significance and Use5.1 The specific airflow resistance of an acoustical materia
20、lis one of the properties that determine its sound-absorptive andsound-transmitting properties. Measurement of specific airflowresistance is useful during product development, for qualitycontrol during manufacture, and for specification purposes.5.2 Valid measurements are made only in the region ofl
21、aminar airflow where, aside from random measurement errors,the airflow resistance (R = P/U) is constant. When the airflowis turbulent, the apparent airflow resistance increases with anincrease of volume velocity and the term “airflow resistance”does not apply.5.3 The specific airflow resistance meas
22、ured by this testmethod may differ from the specific resistance measured by theimpedance tube method in Test Method E384 for two reasons.In the presence of sound, the particle velocity inside a porousmaterial is alternating while in this test method, the velocity isconstant and in one direction only
23、. Also, the particle velocityinside a porous material is not the same as the linear velocitymeasured outside the specimen.6. Apparatus6.1 The apparatus, assembled as shown schematically inFig. 1, consists of the following components:6.1.1 Air Supply, a suction generator or positive air supplyarrange
24、d to draw or force air at a uniform rate through the testspecimen.NOTE 1It may be necessary to use a large surge tank or other meansto reduce pressure fluctuations.6.1.2 Flowmeter, to measure the volume velocity of airflowthrough the specimen. It is preferable to have two or moreflowmeters with over
25、lapping ranges to enable different airflowvelocities to be measured to the same precision.FIG. 1 Schematic Diagram of Airflow ApparatusC522 03 (2009)126.1.3 Differential Pressure Measuring Device, for measur-ing the static pressure difference between the faces of thespecimen with respect to atmosphe
26、re.NOTE 2Aslant manometer or pressure transducer system with a rangefrom 0 to 250 Pa is usually satisfactory, but a second instrument with asmaller range, for example, 0 to 25 Pa, may be necessary for measuringsmall pressures to the desired precision.6.1.4 Specimen-Mounting Assembly, consists essent
27、ially ofa mounting plate and a specimen holder as shown in Fig. 2. Themounting plate has two holes for tube connections to thepressure measuring device and to the airflow supply. Thespecimen holder, which is sealed to the mounting plate, ispreferably a transparent plastic tube at least 150 mm long w
28、itha diameter not less than 50 mm. For testing materials that willsupport themselves, such as disks cut from boards, a slighttaper at the top of holder will enable the specimen to be pressedinto position with a tight fit. For testing materials that will notsupport themselves, a removable screen held
29、 in position at least25 mm above the mounting plate may be used alone or with aplunger assembly that can compress the specimen to a knownthickness. For testing thin materials, such as fabrics or papers,a flange at the top of the holder, together with a clamping ring,will enable the specimen to be he
30、ld securely for testing.Specimens larger than the area of the holder can be tested withsuitable fittings attached to the end of the holder. In such cases,care must be taken to ensure that the airflow through the edgesof the specimen is negligible in comparison to that through theface.NOTE 3If measur
31、ements are made concurrently by the impedancetube method, Test Method E384, the two instruments may convenientlyFIG. 2 Specimen HolderC522 03 (2009)13have the same inside diameter.7. Sampling7.1 Three or more specimens of a uniform sample materialshould be tested. When the sample is not uniform the
32、speci-mens should be selected to include the variations in the properproportion, or several representative specimens of the materialsshould be tested and the results averaged.8. Test Specimens8.1 BoardsRelatively hard, firm materials at least 5 mmthick. For transverse airflow resistance, disks are c
33、ut or sawedfrom the sample with diameter to fit tightly into the specimenholder. Coating the edges of the disks with grease may benecessary to form an airtight seal between the specimen and theholder wall. For lateral airflow resistance, several boards arelaminated together and a new board cut with
34、faces at rightangles to the original faces of the boards. Disks cut from thelaminated board are tested in the usual manner.8.2 BlanketsRelatively soft, flexible materials at least 5mm thick. Disks cut from the sample are laid on the removablescreen. If desired, the plunger assembly may be used tocom
35、press the blanket to the desired thickness. Care must betaken to prevent leakage around the edge of the specimen. Atransparent holder helps in spotting leaks.8.3 SheetsMaterials less than 5 mm thick. Disks withdiameter a little less than the outer diameter of the flange at thetop of the specimen hol
36、der are held in place with the clampingring with grease on the flange to limit the porous part of thespecimen to the inside diameter of the holder. Grease is alsoused to prevent flow of air into the edges of the specimen.Sheet materials with very low specific airflow resistance maybe tested by stack
37、ing layers of specimens separated with airspaces to obtain a measurable pressure drop. The average resultfor a single layer should be reported.9. Procedure9.1 Mount the test specimen according to the type of test tobe made. Seal the specimen holder to the mounting plate andadjust the airflow to give
38、 readable settings on the flowmeterand pressure measuring device. Start at an airflow velocity wellbelow 50 mm/s. Record the differential pressure, P, the flowrate, U, and the calculated quotient, R = P/U.9.2 Repeat the measurements several times, using a largerairflow rate each time. If the apparen
39、t resistance increases in asteady way, the airflow is probably turbulent and the readingsmust be discarded. Make a series of at least three measure-ments at well separated airflow velocities (25 % recommendedminimum differential) below the turbulent level.9.3 Measurements should be made where possib
40、le within atemperature range of 22 6 5C. No adjustment to the calcu-lated results shall be made for barometric pressure.10. Calculation10.1 Calculated the airflow resistance in mks acoustic ohms(Pas/m3) from the expression:R 5 P/U (1)where P/U is the average value of ten or more readings madein the
41、region of laminar airflow.10.2 Calculate the specific airflow resistance in mks rayls(Pas/m) from the expression:r 5 SP/U (2)10.3 Calculate the airflow resistivity in mks rayls/m (Pas/m2) from the expression:r05 SP/TU (3)10.4 See Table 1 to convert from cgs to mks and SI units.11. Report11.1 Report
42、the following information:11.1.1 Complete identification and description of the mate-rial,11.1.2 Type of test and mounting,11.1.3 Description and dimensions of test specimen,11.1.4 Conditioning procedure used, if any,11.1.5 Number of specimens tested,11.1.6 Individual and average values of test resu
43、lts, in mksunits, and11.1.7 Temperature, barometric pressure, and relative hu-midity.11.2 If a test is made intentionally in the transitional orturbulent airflow region, the reason should be given, and thelinear airflow velocities at which the measurements are madeshall be stated.12. Precision and B
44、ias12.1 No quantitative statement on bias can be made at thistime since there is presently no material available with knowntrue values of performance, which can be used for determiningthe bias of this test method.12.2 The within- and between-laboratory precision of thistest method, expressed in term
45、s of the within-laboratory, 95 %Repeatability Interval, I(r), and the between-laboratory, 95 %,Reproducibility Interval, I(R), is listed in Table 2. Thesestatistics are based on the results of a round-robin test programinvolving seven laboratories.12.3 The significance of the Repeatability and Repro
46、duc-ibility Intervals is as follows:12.3.1 Repeatability Interval, I(r)In the same laboratoryon the same material, the absolute value of the difference intwo test results will be expected to exceed I(r) only about 5 %of the time.12.3.2 Reproducibility Interval, I(R)In different laborato-ries on the
47、same material, the absolute value of the differencein two test results will be expected to exceed I(R) only about5 % of the time.TABLE 2 Within-Laboratory Repeatability, I(r), and Between-Laboratory Reproducibility, I(R)MaterialAvg SpecificAirflowResistance(MKS Rayls)Repeat-abilityUncertainty(sr)Rep
48、roduc-ibilityUncertainty(sR)Repeat-abilityIntervalI(r)Reproduc-ibilityIntervalI(R)Scotfelt foam 900.071 2.405 10.577 6.735 29.616C522 03 (2009)1413. Keywords13.1 absorption; acoustical materials; airflow resistance;airflow resistivityANNEX(Mandatory Information)A1. LABORATORY ACCREDITATIONA1.1 Scope
49、A1.1.1 This annex describes procedures for accrediting atesting laboratory to perform tests in accordance with this testmethod. This annex was prepared in accordance with GuideE717 and describes procedures.A1.2 Referenced DocumentsA1.2.1 ASTM Standards:E548 Guide for General Criteria Used for Evaluating Labo-ratory Competence3E717 Guide for Preparation of Accreditation Annex ofAcoustical Test Standards2A1.3 General RequirementsA1.3.1 The testing agency shall make available to theaccrediting authority the information required by Sections 4 to7 of P
