ASHRAE 41 2-1987 Standard Methods for Laboratory Airflow Measurement《实验室气流测定的标准方法》.pdf

1、ASHRAE 41.2 87 0759650 0503773 73T ERRATA SHEET No. 1 FOR ALL COPIES OF ASHRAE STANDARD 41.2-1987 93-03- 11 htrductl on The corrections listed in this errata sheet apply to ail copies of ASHRAE Stanard 41.2-1987. Errata Equation p. 28. pe = 3.25 x (ti) 2+0 0186 ( t;) +Os 692 ANSVASHRAE 41.2-1 987 (R

2、A 92) (Reaffirmation of ANSVASHRAE 41 -2-1 987 with minor editorial changes) AN AMERICAN NATIONAL STANDARD Standard Methods for Laboratory Airflow Measurement Approved by the ASHRAE Standards Committee on June 28, 1987; by the ASHRAE Board of Directors on July 2, 1987, and reaffirmed January 30,1992

3、; approved by the American National Standards Institute on October 1, 1987, and reaffirmed April 20, 1992. ASHRAE Standards are updated on a five-year cycle; the date following the Standard number is the year of ASH- RAE Board of Directors approval. The designation “RA“ followed by a date is the yea

4、r of reaffirmation. The latest copies may be purchased from ASHRAE Publications Sales, 1791 Tullie Circle, NE, Atlanta, GA 30329. “1992 ISSN 1041 -2336 AMERICAN SOCIETY OF HEATING, REFRIGERATING AND AIR-CONDITIONING ENGINEERS, INC. 1791 Tullie Circle, NE Atlanta, GA 30329 I I 0759650 05039i.16 i73 I

5、 ASHRAE STANDARDS PROJECT COMMITTEE 41 2-1 987 Cognizant TC: TC 1.2, Instruments and Measurements Linda L. Alexander, Chairman Alberto A. DeRosa Earl J. Gmoser Gerald P. Jollette Frederick J. Reed Eugene L. Valerio Goerge S. Yamamoto David J. Young ASHRAE STANDARDS COMMITTEE 1991 -92 Donald G. Colli

6、ver, Chairman George Reeves, Vice-chairman M. Kent Anderson Lee W. Burgett, Chairman PPIs Samuel F. Ciricillo Douglas F. Darby Michael E. Dillon, Chairman ILS Donald L. Geistert Ronald H. Howell Daniel E. Kramer Carl N. Lawson Paul L. Miller, Jr. James A. Ranfone Harry J. Sauer, Jr. Max H. Sherman J

7、ohn M. Talbott James E. Woods Thomas P. Wutka, Chairman SPLS Billy R. Manning, CO John F. James, Ex0 Jim L. Heldenbrand, Manager of Standards SPECIAL NOTE This National Voluntary Consensus Standard was developed under the auspices of the American Society of Heating, Refrigerating and Air-Conditionin

8、g Engineers (ASHRAE). Consensus is defined as “substantial agreement reached by concerned interests according to the judgment of a duly appointed authority, after a concerted attempt at resolving objections. Consensus implies much more than the concept of a single majority but not necessarily unanim

9、ity.“ This definition is according to the American National Standards Institute (ANSI) of which ASHRAE is a member. ASHRAE obtains consensus through participation of its national and international members, associated societies, and public review. ASHRAE Standards are prepared by a Project Committee

10、appointed specifically for the purpose of writing the Standard. The Project Committee Chairman and Vice-chairman must be members of ASHRAE; while other committee members may or may not be ASHRAE members, all must be technically qualified in the subject area of the Standard. Every effort is made to b

11、alance the concerned interests on all Project Committees. The Manager of Standards of ASHRAE should be contacted for: a. interpretation of the contents of this Standard, b. participation in the next review of the Standard, c. offering constructive criticism for improving the Standard, d. permission

12、to reprint portions of the Standard. ASHRAE INDUSTRIAL ADVERTISING POLICY ON STANDARDS ASHRAE Standards and Guidelines are established to assist industry and the public by offering a uniform method of testing for rating purposes, by suggesting safe practices in designing and installing equipment, by

13、 providing proper definitions of this equipment, and by providing other information that may serve to guide the industry. The creation of ASHRAE Standards and Guidelines is determined by the need for them, and conformance to them is completely voluntary. In referring to this Standard or Guideline an

14、d in marking of equipment and in advertising, no claim shall be made, either stated or implied, that the product has been approved by ASHRAE. I DISCLAIMER I ASHRAE uses its best efforts to promulgate Standards and Guidelines for the benefit of the public in light of available information and accepte

15、d industry practices. However, ASHRAE does not guarantee, certify, or assure the safety or performance of any products, components, or systems tested, installed, or operated in accordance with ASHRAEs Standards or Guidelines or that any tests conducted under its Standards or Guidelines will be nonha

16、zardous or free from risk. CONTENTS Section Page Foreword 1 1.Purpose 1 2.sco pe 1 3.Definitions . 1 4 . Classifications . 1 5 . Selection of Airflow-Measuring Equipment and Systems . 2 6.Instruments 16 7 . Apparatus and Setups . 23 8.TestProcedure 25 9 . Data to Be Recorded 26 10 . Symbols and Subs

17、cripts . 26 11 . Calculations 28 12.Referen ces . 32 Appendix A-Bibliography . 32 0759650 0503947 bOT - 0759650 0503948 546 (”his foreword is not part of this standard but is in- cluded for information purposes only.) FOREWORD This standard provides recommended practices for airflow measurements as

18、we as measurement procedures for use in the preparation of other ASHRAE standards. Therefore, it meets the ASHRAE standard classification of method of measurement or test. The standard was initiated by the ASHRAE Standards Committee to provide ASHRAE members with several alternatives for laboratory

19、airflow measurements. The standard was developed by a diversified panel of five voting and four nonvoting members using the ANSUMCA Standard 210-85, ANSUASHRAE Standard 51-1985, Laboratory Methods of Testing Fans for Rating, as a reference document. I. PURPOSE 1.1 The purpose of this standard is to

20、set forth recom- mended practices for airflow measurements and to provide adequate and consistent measurement procedures for use in the preparation of other ASHRAE standards. shall and should: the word “shall” is to be understood as a requirement, the word LLshould” as a recommendation. transducer:

21、a device that changes one form of physical quantity to another. In the measurement field, transducers are generally used to sense a variety of measurands, such as line voltage, current, power, pressure, temperature, etc., and convert these to a common output signal for transmission to a controlling,

22、 indicating, or recording instrument. uncertainy, maximum: the maximum difference between the true value of the quantity measured and the observed value. uncertainy, random: an uncertainty that causes readings to take random values on either side of some mean value. Measurements may be precise or im

23、precise depending on how well an instrument can reproduce subsequent readings of an instruments unchanged input. uncertainty, systemaic: an uncertainty that persists and cannot be considered as due entirely to chance. Systematic errors can be corrected by calibration. 4. CLASSIFICATIONS 2. SCOPE 2.1

24、 The procedures described herein are intended for use in testing air-moving, air-handling, and air-distribution equipment and components, The particular method(s) used shall be determined by the operating tolerances, instrument accuracies, and instrument precision required to achieve the objectives

25、of the product test. 2.2 The recommendations herein include consideration of density effects on accurate measurement of flow rates. 2.3 The procedures in this standard are intended primarily for use in laboratory testing of heating, ventilating, air- conditioning, and refrigerating components and eq

26、uipment and do not necessarily apply to field testing of installed equipment and systems. 2.4 The procedures in this standard are intended for application only to flow ineasurements of air at pressures to the measuring equipment not exceeding 100 in. of water (25 kPa) gage. 2.5 Not included are proc

27、edures for testing fans, blowers, exhausters, compressors, and other air-moving devices whose principal function is to produce a stream of moving air, which fall within the scope of ANSI/ASHRAE Standard 51-1985, ANSI/MCA Standard 210-85. 3. DEFINITIONS diameter, equivalent: the diameter of a circle

28、having the same area as the rectangular cross section. diameter, hydraulic: four times the flow area divided by the perimeter of the solid boundary in contact with the fluid. 4.1 General The practices and procedures covered in this standard range from relatively simple applications of measuring the

29、flow rate of a single stream of air brought to the measuring device (which performs its function and then discharges the stream to the atmosphere) to fairly complex systems designed to measure two or more streams entering andlor leaving a product, take leakage and/or ventilation within the product i

30、nto account, and return the main and leakage streams to the product. 4.2 Products Air-conditioning, heating, ventilating, and refrigerating products for which airflow measurements are required may be classified by their relationship within a complete heating, ventilating, air-conditioning, or refrig

31、er- ating system. 4.2.1 Unitary Equipment This covers products in which the intended functions of heating, humidifying, cooling, dehumidifying, and means for air moving of one or more streams of air, such as conditioned or refrigerated air, are camed out in a factory-assembled package or packages de

32、signed by the manufacturer to be used together. These products may be supplemented by one or more duct systems plus fans, registers, grilles, filters, and other accessories as required to form the complete heating, ventilating, air-conditioning, or refrigerating system. Some examples are: a. unitary

33、 air conditioners, b. unitary heat pumps, c. room air conditioners, d. packaged terminal air conditioners and heat e. central forced-circulation warm-air furnaces. pumps, ANSVASHRAE 41.2-1987 (RA 92) 1 4.2.2 Applied Systems Components These are products selected by the system designer to perform one

34、 or more specified functions of heating, humidifying, cooling, or dehumidifjing, with means of moving one or more airstreams or of utilizing one or more airstreams motivated outside the product, and field-installed, to form a complete system. Some examples are: a. combinations of specified packages

35、of single- package or split unitary air-conditioning or heat pump equipment; b. packaged terminal air conditioners and heat c. centrai-station air-handling units; d. e. unit heaters; f. unit ventilators; g. unit coolers; h. room fan-coil air conditioners; i. air-cooled refrigerant condensers; j . k.

36、 air-to-air heat exchangers. pumps; centrifugal, reciprocating, or absorption water- chilling packages; forced-circulation air-cooling and air-heating coils; 4.3 Airflow Provisions Equipment and system compo- nents involved in airflow measurements may be classified as t the source of the airstream m

37、ovement, that is, wheth- er it is generated internally or externally to the product. 4.3.1 Airflow-Generating Products These are prod- ucts containing the necessary elements to generate the flow of at least one stream of air. 4.3.1.1 Nonducted Inlet and Outlet These are products drawing in air from

38、the space in which the air inlet is located and delivering the air directly to the space in which the air outlet is located. Some examples are: a. room air Conditioners, b. unit ventilators, c. unit coolers, d. room fan-coil air conditioners, e. room air-induction units, f. air-cooled condensing uni

39、ts, g. air-cooled refrigerant condensers, h. packaged terminal air conditioners, i. j. evaporative condensers, k. 1. humidifiers, m. dehumidifiers. some single-package unitary air conditioners, certain types of heat pumps, 4.3.1.2 Ducted Inlet and Nonducted Outlet These products receive air from an

40、inlet duct and deliver the air directly (free delivery) to the space in which the air is located. Some examples are: a. exhaust fans, b. some ventilating units. 4.3.1.3 Nonducted Inlet, Ducted Outlet These products receive air from the space in which they are located and deliver it to a duct system.

41、 Some examples are: certain types of unit ventilators, packaged unitary air conditioners and heat pumps, a. b. c. humidifiers, d. dehumidifiers, e. ventilating units. 2 4.3.1.4 Ducted Inlet and Outlet These products receive air from a duct system and return it to another duct system. Some examples a

42、re: a. unitary air conditioners and heat pumps, b. central-station air-handling units, c. central warm-air furnaces and heaters, d. fans as components of a field-assembled system, e. certain types of ventilating units. 4.3.2 Air Pass-through Products These are products that are duct connected in a s

43、ystem, with airflow genera- tion provided elsewhere in the system. Some examples are: air-cooling and air-heating coils as components of air-to-air or water-to-air heat exchangers as com- mixing boxes as components of a duct system. a. air inlets and outlets, b. c. d. a field-assembled system, ponen

44、ts of a field-assembled system, 4.4 Airflow-Measuring Equipment These are movable or fixed laboratory devices providing necessary instruments and, as required, flow-measurement chambers, airflow- generating devices, dampers, etc., as needed to control the pressures and/or rates of flow of the airstr

45、eam being measured. The most common types of airflow-measuring equipment are classified in the following: 4.4.1 Test Ducts These are described in 5.2. 4.4.2 Test Chambers (Code Testers)* These are described in 5.3. 4.4.3 Calorimetric (Heat Exchanger) Chambers These are described in 5.4. 4.4.4 Room C

46、alorimeter Systems These are de- scribed in 5.5. 5. SECTION OF AIRFLOW-MEASURING EQUIPMENT AND SYSTEMS 5.1 General The type of airflow-measuring equipment or system to be used depends upon the nature and complexity of the product being tested, including complexities of the air system(s) within the p

47、roduct. It may also involve consideration of energy requirements, both for operation of the product and of the measurement system; this could also involve means for energy exchanges for conservation and economy of operation of the laboratory system. In addition, ease, convenience, and automation of

48、the testing system are important considerations. However, this standard will deal primarily with the basic arrangements, principles of operation, required data, and calculations of results. Since it is established practice to express airflow measurements in terms of standard air, each type of system

49、 requires a barometer for measuring ambient air pressure. 5.2 Test Ducts A test duct (Figures 1, 2, and 3) is used most commonly for testing products that receive or dis- charge an airstream having essentially uniform temperature and/or moisture content. It may be used to provide a pressure-measuring station or to simulate the condition(s) the product is expected to encounter in service or both. It may employ either a Pitot tube traverse arrangement (Figures 4 and 5) or a nozzle (Figure 6) on the inlet or *Test chamber is the generic name applied to these devices, but code tester ha