ASHRAE41[1].1-1986-温度测量标准方法

ASHRAE STANDARDASHRAE STANDARD American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. 1791 Tullie Circle NE, Atlanta, GA 30329 www.ashrae.org Standard Method for Temperature Measurement ANSI/ASHRAE Standard 41.1-1986 (RA 2006) Reaffirmation of ANSI/ASHRAE Standard 41.1-1986 Approved by the ASHRAE Standards Committee on October 26, 1986, and reaffirmed on January 21, 2006; by the ASHRAE Board of Directors on December 12, 1986, and reaffirmed on January 26, 2006; and by the American National Standards Institute on February 18, 1987, and reaffirmed on January 27, 2006. ASHRAE Standards are scheduled to be updated on a five-year cycle; the date following the standard number is the year of ASHRAE Board of Directors approval. The latest copies may be purchased from ASHRAE Customer Service, 1791 Tullie Circle, NE, Atlanta, GA 30329-2305. E-mail: orders@ashrae.org. Fax: 404-321-5478. Tele- phone: 404-636-8400 (worldwide) or toll free 1-800-527-4723 (for orders in US and Canada). © Copyright 2006 ASHRAE, Inc. ISSN 1041-2336 When addenda, interpretations, or errata to this standard have been approved, they can be downloaded free of charge from the ASHRAE Web site at http://www.ashrae.org. Copyright ASHRAE Provided by IHS under license with ASHRAE Not for ResaleNo reproduction or networking permitted without license from IHS --`,,```,,,,````-`-`,,`,,`,`,,`--- SPECIAL NOTE This American National Standard (ANS) is a national voluntary consensus standard developed under the auspices of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Consensus is defined by 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 than 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. ASHRAE 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 Project Committee Chair and Vice-Chair 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 balance 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 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 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 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. DISCLAIMER ASHRAE uses its best efforts to promulgate Standards and Guidelines for the benefit of the public in light of available information and accepted 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 ASHRAE’s Standards or Guidelines or that any tests conducted under its Standards or Guidelines will be nonhazardous or free from risk. ASHRAE STANDARDS COMMITTEE 2005-2006 Richard D. Hermans, Chair David E. Knebel, Vice-Chair Donald L. Brandt Steven T. Bushby Paul W. Cabot Hugh F. Crowther Samuel D. Cummings, Jr. Robert G. Doerr Hakim Elmahdy Roger L. Hedrick John F. Hogan Frank E. Jakob Stephen D. Kennedy Jay A. Kohler James D. Lutz Merle F. McBride Mark P. Modera Cyrus H. Nasseri Stephen V. Santoro Stephen V. Skalko David R. Tree Jerry W. White, Jr. James E. Woods William E. Murphy, BOD ExO Ronald E. Jarnagin, CO Claire B. Ramspeck, Assistant Director of Technology for Standards and Special Projects ASHRAE Standing Standard Project Committee 41.1 Cognizant TC: TC 1.2, Instruments and Measurements SPLS Liaison: Steve Bushby Robert J. Evans, Chair David R. Tree Alberto Da Rosa George S. Yamamoto Scott Farley David J. Young Copyright ASHRAE Provided by IHS under license with ASHRAE Not for ResaleNo reproduction or networking permitted without license from IHS - - ` , , ` ` ` , , , , ` ` ` ` - ` - ` , , ` , , ` , ` , , ` - - - CONTENTS ANSI/ASHRAE Standard 41.1-1986 (RA 2006) Standard Method for Temperature Measurement SECTION PAGE Foreword................................................................................................................................................................... 2 1 Purpose .......................................................................................................................................................... 2 2 Scope ............................................................................................................................................................. 2 3 Definitions....................................................................................................................................................... 2 4 Instruments..................................................................................................................................................... 2 5 Measurement Techniques—General .............................................................................................................. 4 6 Airstream Temperature Measurements .......................................................................................................... 5 7 Water, Brine, and Nonvolatile Refrigerant Temperature Measurements......................................................... 9 8 Volatile Refrigerant Temperature Measurements ......................................................................................... 10 9 Measurement Techniques—Mercury-in-Glass Thermometers..................................................................... 10 10 Measurement Techniques—Thermocouples ................................................................................................ 11 11 Measurement Techniques—Resistance Thermometers............................................................................... 12 Appendix A: Bibliography.................................................................................................................................. 13 NOTE When addenda, interpretations, or errata to this standard have been approved, they can be downloaded free of charge from the ASHRAE Web site at http://www.ashrae.org. © Copyright 2006 American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. 1791 Tullie Circle NE Atlanta, GA 30329 www.ashrae.org All rights reserved. Copyright ASHRAE Provided by IHS under license with ASHRAE Not for ResaleNo reproduction or networking permitted without license from IHS --`,,```,,,,````-`-`,,`,,`,`,,`--- 2 ANSI/ASHRAE Standard 41.1-1986 (RA 2006) (This foreword is not a part of this standard. It is merely informative and does not contain requirements necessary for conformance to the standard. It has not been processed according to the ANSI requirements for a standard and may contain material that has not been subject to public review or a consensus process.) FOREWORD This is a reaffirmation of ASHRAE Standard 41.1-1986. This standard was prepared under the auspices of the Ameri- can Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). It may be used, in whole or in part, by an association or government agency with due credit to ASHRAE. Adherence is strictly on a voluntary basis and merely in the interests of obtaining uniform standards throughout the industry. This standard was written to establish methods of temper- ature measurement that provide consistent procedures that may be referenced in other ASHRAE standards. There were no changes made for the 2006 reaffirmation. 1. PURPOSE The purpose of this standard is to set forth recommended practices for temperature measurements and provide adequate and consistent measurement procedures for reference in other standards. 2. SCOPE The procedures described herein are intended for use in testing heating, refrigerating, and air-conditioning equipment and components. The media in which temperature measure- ments are made include air, water, brine, and volatile or nonvolatile refrigerants, under both steady-state and transient temperature conditions between -40ºF and 400ºF (-40ºC and 204ºC). 3. DEFINITIONS accuracy: the ability of an instrument to indicate or record the true value of a measured quantity. The error of indication, which is the difference between the indicated value and the true value of the measured quantity, expresses the accuracy of an instrument. precision: closeness of agreement among repeated measure- ments of the same physical quantity by the same method under the same conditions and with the same instrument. (An instru- ment may be precise but not accurate.) saturation deficiency: the amount that the humidity ratio of an air sample is below the saturated humidity ratio of air at the same temperature and pressure. sensitivity: the relationship between an observed change in the position of an instrument pen, pointer, or indicator and the magnitude of change in the measured quantity required to produce that reaction of the indicator. It can be expressed as a numerical ratio if the units of measurement of the two quan- tities are stated. An increase in sensitivity means a correspond- ing increase in the ability of an instrument to react to extremely small changes in the measured quantity. shall: where "shall" or "shall not" is used for a provision, that provision is mandatory if compliance with the standard is claimed. should: "should" or "should not" is used to indicate provisions that are not mandatory but that are desirable as good practice. steady-state conditions: an operating state of a system, includ- ing its surroundings, in which the extent of change with time of all the significant parameters is so small as to have no important effect on the performance being observed or measured. temperature, dry-bulb: the temperature of a gas or mixture of gases indicated by an accurate thermometer after correction for radiation. temperature, wet-bulb: the temperature at which liquid or solid water, by evaporating into air, can bring the air to satu- ration adiabatically at the same temperature. Wet-bulb temper- ature (without qualification) is the temperature indicated by a wet-bulb psychrometer constructed and used according to specifications. transducer: a device that changes one form of physical quan- tity into another. In the measurement field, transducers are generally used to sense a variety of measurands, such as line voltage, current, power, pressure, and temperature, and to convert these to a common output signal for use with a control- ling or recording instrument. transient state: the state in which the system undergoes a normal change in operation, such as thermostat cycling or actuation of a defrost control. 4. INSTRUMENTS 4.1 Temperature measurements shall be made with an instrument or instrument system, including read-out devices, meeting the accuracy and precision requirements in Table 1. The following are in common use for this purpose but are not all-inclusive: a. Liquid-in-glass thermometers b. Thermocouples c. Electric resistance thermometers, including thermistors In general, the response time of liquid-in-glass ther- mometers is too large to be used in transient testing. 4.2 The rate of heat flow to or from a moving fluid under steady-state conditions is determined by the product of the enthalpy change and the mass flow rate for the fluid. The mea- surement of heat flow involves two situations that allow dif- ferent levels of accuracy in temperature measurement to produce equivalent levels of accuracy in the heat flow mea- surement. a. For the case of flow of air, water, or nonvolatile refriger- ant, relatively small changes in enthalpy are predomi- nantly due to sensible heat changes. These are associated Copyright ASHRAE Provided by IHS under license with ASHRAE Not for ResaleNo reproduction or networking permitted without license from IHS - - ` , , ` ` ` , , , , ` ` ` ` - ` - ` , , ` , , ` , ` , , ` - - - ANSI/ASHRAE Standard 41.1-1986 (RA 2006) 3 with comparatively large mass flow rates. The small mag- nitude of the enthalpy change requires the determination of temperature and, in turn, temperature differences with considerable accuracy. b. For the case of flow of a volatile refrigerant, a change of state is involved and relatively large changes in enthalpy are associated with comparatively small mass flow rates. Less accuracy in temperature measurement is required to obtain a desired level of accuracy in heat flow rate mea- surement. Note: In two-phase measurements, temperature and mass flow rate alone are not sufficient to determine heat flow. 4.3 For transient testing, in addition to those requirements listed in Table 1, the instrumentation used shall have the fol- lowing capabilities: a. Continuously recording the data used in the calculation. For this standard, continuous recording for sampling sys- tems used for this purpose shall have the following maxi- mum intervals of sampling: • For steady-state tests—1 minute • For the rate of temperature change 1.0°F/s (0.5°C/s) or greater—5 seconds 0.5°F/s to 1.0°F/s (0.25 to 0.50°C/s)—10 seconds less than 0.5°F/s (0.25°C/s)—20 seconds b. Continuously recording the data used for room control. For this standard, continuous recording for sampling sys- tems used for this purpose shall have the following maxi- mum intervals of sampling: • For steady-state testing—1 minute • For transient testing—20 seconds c. Achieving a total system accuracy within ±0.3ºF (±0.17°C) of individual values. d. Achieving a total system response time of 2.5 seconds or less. The response time for this standard is defined as the time required for the system to obtain 63% of the final steady-state value when the transducer is subjected to a step change in temperature of 15°F (8°C) or more The test for system response time shall be made in the same fluid and at the same velocity as observed at the location where the temperature will be measured. When using temperature transducers in series or parallel (such as thermocouple grids or thermopiles) to obtain the aver- age temperature or average temperature differences in a duct with nonuniform velocities, the overall response time can be much larger than the response time measured at the average velocity. For this standard, the response time for such measurements is defined as the overall response time measured at the velocity conditions of the actual tests. TABLE 1 Instrument and Test Tolerances for Temperature Measurement Item Measured Instrument Accuracy (See Section 4.6) Instrument Pre- cision (See Section 4.6) Recommended Test Operating Toler- ance (Total Observed Range) (Note 1) Recommended Test Condition Tolerance (Variation of Average from Specified Test Condition) (Note 2) Measurements are Usually within Range Air dry-bulb temperature* ± 0.2ºF ± 0.1ºC ± 0.1ºF ±0.05ºC 1.0ºF 0.5ºC 0.5ºF 0.3ºC –20 to 140ºF –29 to 60ºC Air wet-bulb temperature* ± 0.2ºF ± 0.1ºC ± 0.1ºF ± 0.05ºC 0.6ºF 0.3ºC 0.3ºF 0.2ºC 0 to 90ºF –18 to 32ºC Water or nonvolatile refrigerant temperature* ± 0.2ºF ± 0.1ºC ± 0.1ºF ± 0.05ºC 0.5ºF 0.3ºC 0.2ºF 0.1ºC 30 to 110ºF –1 to 43ºC Water or nonvolatile refrigerant temperature** ± 0.2ºF ± 0.1ºC ± 0.1ºF ± 0.05ºC 0.3ºF 0.2ºC — 5 to 25ºF 3 to 14ºC Volatile refrigerant*** ± 1.0ºF ± 0.6ºC ± 0.5ºF ± 0.3ºC — — –30 to 250ºF –34 to 121ºC Other temperatures required for other purposes**** — — 0 to 300ºF –18 to 149ºC * Items are used to determine fluid temperature change and, in conuunction with flow rate, the cooling or heating flow rates. ** Applicable where the temperature difference is measured with a single instrument. *** Includes refrigerant tube temperatures where acceptable in lieu of immersion of instrument within refrigerant stream. ****Other temperatures not required by ASHRAE standards but frequently taken for other purposes: for example, refrigerant system component temperatures, motor winding temperatures, or electrical component temperatures. Note 1—This is the recommended tolerance to be specified on individual readings in a series of readings to be averaged over the duration of the test. Greater tolerances may be specified in specific standards for circumstances such as frosting and defrosting. Note 2—Test conditions are recommended to average within the tolerance shown. Exceptions may be specified for special situations such as frosting and defrosting (see note1). Copyright ASHRAE Provided by IHS under license with ASHRAE Not for ResaleNo reproduction or networking permitted without license from IHS - - ` , , ` ` ` , , , , ` ` ` ` - ` - ` , , ` , , ` , ` , , ` - - - 4 ANSI/ASHRAE Standard 41.1-1986 (RA 2006) 4.4 In no case shall the smallest scale division of the instru- ment exceed twice the specified precision. For example, if the specified precision is ±0.10ºF (±0.05ºC), the smallest scale division shall not exceed 0.20ºF (0.10ºC). 4.5 Where an accuracy better than ±0.50ºF (±0.30ºC) is specified, the instrument shall be calibrated by comparison with a National Institute of Standards and Technology cali- brated primary or secondary standard or shall itself be simi- larly calibrated. The indicated corrections shall be applied to obtain the required accuracy. In this range of accuracy, mer- cury- in-glass or platinum resistance thermometers or individ- ually calibrated thermocouples or thermistors are recommended. 4.6 Wherever possible, temperature-measuring instruments used to measure the change in temperature of a liquid or a gas should be arranged so that they can readily be interchanged between inlet and outlet positions after every reading. This will improve the accuracy of temperature difference measure- ment. 4.7 Whenever possible, temperature measurements down- stream of a potential heat source or sink should be compared with upstream measurements under conditions of steady tem- perature with fluid flow but with no heating flow. This cali- bration may identify problems with the instrumentation or the test setup. 4.8 Whenever two instruments are used to measure a small temperature difference, the investigator should recognize the effect of individual instrument accuracies on the accuracy of the calculated temperature difference. Obtaining system accuracies comparable to those in Table 1 will require careful calibration. 5. MEASUREMENT TECHNIQUES—GENERAL 5.1 The measurement of the flow of heat usually involves the measurement of flow of a fluid and determination of its entering and leaving enthalpy. The enthalpy depends on