ASHRAE 120-2017 Method of Testing to Determine Flow Resistance of HVAC Ducts and Fittings.pdf

1、ANSI/ASHRAE Standard 120-2017(Supersedes ANSI/ASHRAE Standard 120-2008)Method of Testingto DetermineFlow Resistance ofHVAC Ducts and FittingsApproved by ASHRAE on January 31, 2017, and by the American National Standards Institute on February 1, 2017.ASHRAE Standards are scheduled to be updated on a

2、five-year cycle; the date following the Standard number is the year ofASHRAE approval. The latest edition of an ASHRAE Standard may be purchased on the ASHRAE website (www.ashrae.org)or from ASHRAE Customer Service, 1791 Tullie Circle, NE, Atlanta, GA 30329-2305. E-mail: ordersashrae.org. Fax: 678-5

3、39-2129. Telephone: 404-636-8400 (worldwide) or toll free 1-800-527-4723 (for orders in US and Canada). For reprintpermission, go to www.ashrae.org/permissions. 2017 ASHRAE ISSN 1041-2336SPECIAL NOTEThis American National Standard (ANS) is a national voluntary consensus Standard developed under the

4、auspices of ASHRAE. Consensus is definedby the American National Standards Institute (ANSI), of which ASHRAE is a member and which has approved this Standard as an ANS, as“substantial agreement reached by directly and materially affected interest categories. This signifies the concurrence of more th

5、an a simple majority,but not necessarily unanimity. Consensus requires that all views and objections be considered, and that an effort be made toward their resolution.”Compliance with this Standard is voluntary until and unless a legal jurisdiction makes compliance mandatory through legislation. ASH

6、RAE obtains consensus through participation of its national and international members, associated societies, and public review.ASHRAE Standards are prepared by a Project Committee appointed specifically for the purpose of writing the Standard. The ProjectCommittee Chair and Vice-Chair must be member

7、s of ASHRAE; while other committee members may or may not be ASHRAE members, allmust be technically qualified in the subject area of the Standard. Every effort is made to balance the concerned interests on all Project Committees. The Senior Manager of Standards of ASHRAE should be contacted fora. in

8、terpretation of the contents of this Standard,b. participation in the next review of the Standard,c. offering constructive criticism for improving the Standard, ord. permission to reprint portions of the Standard.DISCLAIMERASHRAE uses its best efforts to promulgate Standards and Guidelines for the b

9、enefit of the public in light of available information and acceptedindustry practices. However, ASHRAE does not guarantee, certify, or assure the safety or performance of any products, components, or systemstested, installed, or operated in accordance with ASHRAEs Standards or Guidelines or that any

10、 tests conducted under its Standards or Guidelineswill be nonhazardous or free from risk.ASHRAE INDUSTRIAL ADVERTISING POLICY ON STANDARDSASHRAE Standards and Guidelines are established to assist industry and the public by offering a uniform method of testing for rating purposes, bysuggesting safe p

11、ractices in designing and installing equipment, by providing proper definitions of this equipment, and by providing other informationthat may serve to guide the industry. The creation of ASHRAE Standards and Guidelines is determined by the need for them, and conformanceto them is completely voluntar

12、y.In referring to this Standard or Guideline and in marking of equipment and in advertising, no claim shall be made, either stated or implied,that the product has been approved by ASHRAE.ASHRAE Standing Standard Project Committee 120Cognizant TC: 5.2, Duct DesignSPLS Liaison: Peter SimmondsKevin J.

13、Gebke*, Chair Gary L. Miller*, Secretary Alex M. Kouvolo*Herman F. Behls*, Vice-Chair Patrick J. Brooks* Stephen R. Wiggins*Stephen A. Idem* Denotes members of voting status when the document was approved for publicationASHRAE STANDARDS COMMITTEE 20162017Rita M. Harrold, Chair Michael W. Gallagher C

14、yrus H. NasseriSteven J. Emmerich, Vice-Chair Walter T. Grondzik David RobinJames D. Aswegan Vinod P. Gupta Peter SimmondsNiels Bidstrup Susanna S. Hanson Dennis A. StankeDonald M. Brundage Roger L. Hedrick Wayne H. Stoppelmoor, Jr.Drury B. Crawley Rick M. Heiden Jack H. ZarourJohn F. Dunlap, Sriniv

15、as Katipamula William F. Walter, BOD ExOJames W. Earley, Jr. Cesar L. Lim Patricia Graef, COKeith I. Emerson Arsen K. MelikovJulie M. Ferguson R. Lee Millies, Jr.Stephanie C. Reiniche, Senior Manager of StandardsCONTENTSANSI/ASHRAE Standard 120-2017,Method of Testing to Determine Flow Resistance of

16、HVAC Ducts and FittingsSECTION PAGEForeword .21 Purpose.22 Scope23 Definitions, Symbols, and Subscripts24 Compliance Requirements35 Applicability .36 Instrumentation .37 Flow Measuring Systems and Test Setups.68 Observations and Conduct of Test89 Calculations.910 Test Results and Report1311 Referenc

17、es13Informative Annex ATime-Weighted Average33Informative Annex BLeakage Measurement35Informative Annex CFlexible Duct Test Setup Guide 41Informative Annex DExample Test Systems .45NOTEApproved addenda, errata, or interpretations for this standard can be downloaded free of charge from the ASHRAEwebs

18、ite at www.ashrae.org/technology. 2017 ASHRAE1791 Tullie Circle NE Atlanta, GA 30329 www.ashrae.org All rights reserved.ASHRAE is a registered trademark of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.ANSI is a registered trademark of the American National Stand

19、ards Institute.2 ANSI/ASHRAE Standard 120-2017(This foreword is not part of the standard. It is merelyinformative and does not contain requirements necessaryfor conformance to the standard. It has not been pro-cessed according to the ANSI requirements for a standardand may contain material that has

20、not been subject topublic review or a consensus process. Unresolved objec-tors on informative material are not offered the right toappeal at ASHRAE or ANSI.)FOREWORDFirst published in 1999, ASHRAE Standard 120 establishesuniform methods of laboratory testing of HVAC ducts and fit-tings to determine

21、their resistance to airflow. The fittinglosses, which are reported as local loss coefficients, are usedto update and refine the ASHRAE Duct Fitting Database. Todate, at least eight research projects have used the test meth-ods of Standard 120 to improve this database. The significantchange to this e

22、dition of the standard is that the lengthupstream of the test duct or fitting was increased from 10 to15 hydraulic diameters.1. PURPOSEThis standard establishes uniform methods of laboratory test-ing of HVAC ducts and fittings to determine their resistanceto airflow.2. SCOPE2.1 This standard may be

23、used to determine the change intotal pressure resulting from airflow in HVAC ducts and fit-tings.2.2 The test results can be used to determine duct flow lossesin pressure loss per unit length. Fitting losses are reported aslocal loss coefficients.2.3 This standard does not cover interpretation of te

24、st data.3. DEFINITIONS, SYMBOLS, AND SUBSCRIPTS3.1 Definitions accuracy: the degree of conformity of an indicated value toan accepted standard value or true value. The degree of inac-curacy is known as “total measurement error” and is the sumof bias error and precision error.bias error (systematic e

25、rror): the difference between the trueor actual value to be measured and the indicated value fromthe measuring system that persists and is usually due to theparticular instrument or technique of measurement. Theseerrors can be corrected through calibration.confidence level: the probability that a st

26、ated interval willinclude the true value. In analyzing experimental data, a levelof 95% is usually used.duct, flexible: any duct constructed of flexible materials, suchas polymeric films, metal foils, and impregnated fabrics.duct, rigid: any duct constructed of rigid materials, such asmetal and fibe

27、rglass duct board.error: the difference between the true value of the quantitymeasured and an observed value. Because the true value isoften not known, it is estimated by the mean. The differencebetween the mean and the observed value is often called its“deviation.” All errors can be classified as o

28、ne of two types:bias error or random error.flow area, fitting inlet: the measured total inside area deter-mined at the plane(s) of the inlet connection(s). The area shallbe based on physical measurements for rigid fittings andphysical measurements minus twice the lining thickness forlined fittings.f

29、low area, fitting outlet: the total inside area determined atthe plane(s) of the outlet connection(s). The area shall bebased on physical measurements for rigid fittings and physi-cal measurements minus twice the lining thickness for linedfittings.flow area, flexible duct: the area calculated using

30、the nominalinside dimensions supplied by the duct manufacturer.flow area, lined duct: the area calculated by subtracting thecross-sectional area of the liner from the flow area of the rigidduct envelope. The duct flow area shall be calculated frommeasured inside dimensions of the rigid duct envelope

31、. Forfully lined ducts, the nominal area is that calculated by reduc-ing the cross-sectional dimensions of the rigid duct by twicethe nominal liner thickness. The envelope dimensions shall bemeasured at a minimum of three representative sections of thetest duct.flow area, rigid duct: the area calcul

32、ated by using the averageinside duct dimensions determined by measurement of a min-imum of three representative sections of the duct envelope.precision: the closeness of agreement among repeated mea-surements of the same characteristic by the same methodunder the same conditions.pressure loss: the d

33、ecrease in total pressure due to frictionand turbulence. It is a measure of the mechanical energy lostby the flow per unit volume of the fluid.random error (precision error): a statistical error that iscaused by chance and is not recurring.static pressure: pressure that exists only by virtue of thed

34、egree of compression. If expressed as gage pressure, it maybe negative or positive.test: a complete series of test points defining the flow behav-ior over a selected range of velocities. test air density: the density of the air entering the test duct orfitting.test flow rate: the volumetric flow rat

35、e entering the test ductor fitting at the test air density.test pressure determination: a complete set of measurementsrequired to determine the total pressure loss at a test point.test pressure loss: the differential in total pressure betweenthe inlet and the outlet sections of a test duct or across

36、 a testfitting. For test fittings, the fitting is assumed to have zerolength. For multiflow fittings, the total pressure loss shall bedetermined for each stream separately.test system: the prescribed flow rate measurement system andprescribed test setup for the duct or fitting test.ANSI/ASHRAE Stand

37、ard 120-2017 3total pressure: the sum of the static pressure and the velocitypressure. It is a measure of the mechanical energy per unitvolume of the air. Air at rest has a total pressure equal to itsstatic pressure.uncertainty: a measure of the potential error in a measure-ment or experimental resu

38、lt that reflects the lack of confi-dence in the result to a specified level.uncertainty range (confidence level): the band for the errorin an estimate at a certain confidence level.velocity pressure: the kinetic energy of the air motionexpressed in pressure units. It is always positive.3.2 Symbols a

39、nd Subscripts. Table 1 displays symbols andsubscripts used throughout this standard, along with theirunits and description.4. COMPLIANCE REQUIREMENTS4.1 A duct or fitting test complies with this standard if therequirements of Section 6, “Instrumentation,” and Section 7,“Flow Measuring Systems and Te

40、st Setups,” have been met.4.2 A person or persons determining compliance shall statein writing that the test procedures and general test require-ments of Section 8, “Observations and Conduct of Test,” havebeen met.4.3 A person or persons determining compliance shall statein writing that the calculat

41、ion requirements of Section 9,“Calculations,” and Section 10, “Test Results and Report,”have been met.5. APPLICABILITY5.1 Type of Ducts. This standard specifies test conditions forrigid and flexible ducts of rectangular, round, flat oval, orother shapes constructed to contain airflow. Elastic materi

42、alsthat change size greater than 5% of any linear dimension withflow conditions are not covered by this standard.5.2 Type of Fittings. This standard specifies test conditionsfor fittings designed for use with the ducts described in Sec-tion 5.1.5.3 Sizes. This standard covers test conditions for duc

43、ts withan internal hydraulic diameter 50 mm or larger.5.4 Test Air Velocities. This standard specifies test condi-tions for velocities in the range from 6 m/s to 36 m/s.5.5 Measured Pressure Differential. The minimum pres-sure loss for a fitting shall be 75 Pa.6. INSTRUMENTATION6.1 Accuracy and Prec

44、ision. Measurements from the instru-ments shall be traceable to primary or secondary standardscalibrated by the National Institute of Standards and Technol-ogy (NIST) or to the Bureau International des Poids etMesures (BIPM) if a National Metrology Institute (NMI)other than NIST is used. In either c

45、ase, the indicated correc-tions shall be applied to meet the accuracy and precisionstated in this standard. Instruments shall be calibrated on aregular basis that is appropriate for each instrument but in nocase less than annually. Calibration records shall be main-tained. Instrument accuracy and pr

46、ecision shall be as follows:a. Pressure shall be measured with accuracy equal to or betterthan 1.0 Pa and a precision equal to or better than 0.5 Pa.b. Temperature measurements shall be made using deviceswith an accuracy equal to or better than 1C and with aprecision equal to or better than 0.5C.c.

47、Airflow shall be measured with accuracy equal to or betterthan 2% of measured flow. Nozzles and orifices meetingthe requirement of this standard are considered referenceflow measuring devices and therefore do not need calibra-tion.d. Barometric pressure shall be measured with accuracyequal to or bet

48、ter than 25 Pa.6.2 Pressure6.2.1 Pressure indicating instruments shall comply withASHRAE Standard 41.31.6.2.2 Calibration. Each pressure instrument shall be cali-brated to traceable standards per Section 6.1. 6.2.3 Time Averaging. Because the flow and pressures infan-driven duct systems are never st

49、rictly steady, the pressureindicated on any instrument may fluctuate with time. Thereadings shall be averaged in a suitable manner to obtain anaccurate value. Averaging can sometimes be accomplishedmentally, particularly if the fluctuations are small and regular.Multipoint or continuous record averaging is permissiblewhen accomplished with instruments and analyzers designedfor this purpose. Examples of acceptable methods are given inInformative Annex A.6.2.4 Corrections. All pressure measuring instrumentsshall be corrected for temperature.6.3 Static Pressure Wall Taps