1、 2016 Standard for Performance Rating of Thermostatic Refrigerant Expansion Valves AHRI Standard 751 (SI) Price $10.00 (M) $20.00 (NM) Copyright 2016, by Air-Conditioning, Heating, and Refrigeration Institute Printed in U.S.A. Registered United States Patent and Trademark Office IMPORTANT SAFETY DIS
2、CLAIMER AHRI does not set safety standards and does not certify or guarantee the safety of any products, components or systems designed, tested, rated, installed or operated in accordance with this standard/guideline. It is strongly recommended that products be designed, constructed, assembled, inst
3、alled and operated in accordance with nationally recognized safety standards and code requirements appropriate for products covered by this standard/guideline. AHRI uses its best efforts to develop standards/guidelines employing state-of-the-art and accepted industry practices. AHRI does not certify
4、 or guarantee that any test conducted under its standards/guidelines will be non-hazardous or free from risk. Note: This standard supersedes AHRI Standard 750-2007. For I-P ratings, see AHRI Standard 750 (I-P)-2016. AHRI Standard 750 (formerly ARI Standard 750) TABLE OF CONTENTS SECTION PAGE Section
5、 1. Purpose 1 Section 2. Scope . 1 Section 3. Definitions . 1 Section 4. Test Requirements . 2 Section 5. Rating Requirements . 2 Section 6. Minimum Data Requirements for Published Ratings . 3 Section 7. Marking and Nameplate Data 4 Section 8. Conformance Conditions 4 TABLES Table 1. Standard Rating
6、 Conditions 3 APPENDICES Appendix A. References - Normative . 5 Appendix B. References - Informative . 5 Appendix C. Recommended MOP for Pressure-Limiting Type Thermostatic Refrigerant Expansion Valves - Informative . 6 Appendix D. Recommended Standard Connection Sizes - Informative . 7 TABLES FOR A
7、PPENDICES Table C1. Recommended MOP for Pressure-Limiting Type Thermostatic Refrigerant Expansion Valves 6 Table D1. Recommended Standard Connection Sizes . 7 AHRI STANDARD 751 (SI)-2016 1 PERFORMANCE RATING OF THERMOSTATIC REFRIGERANT EXPANSION VALVES Section 1. Purpose 1.1 Purpose. The purpose of
8、this standard is to establish for Thermostatic Refrigerant Expansion Valves: definitions; test requirements; rating requirements; minimum data requirements for Published Ratings; marking and nameplate data; conformance conditions. 1.1.1 Intent. This standard is intended for the guidance of the indus
9、try, including manufacturers, engineers, installers, contractors and users. 1.1.2 Review and Amendment. This standard is subject to review and amendment as technology advances. Section 2. Scope 2.1 Scope. This standard applies to Thermostatic Refrigerant Expansion Valves for use with refrigerants li
10、sted in Section 2.1.1 at evaporator temperatures between 10C and -40C. 2.1.1 Refrigerants. The type of refrigerants applicable to this standard are: hydrofluoroolefins (HFOs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and hydrocarbons (HCs). Section 3. Definitions All terms in thi
11、s document shall follow the standard industry definitions in the ASHRAE Terminology website (https:/www.ashrae.org/resources-publications/free-resources/ashrae-terminology), unless otherwise defined in this section. 3.1 Capacity of Thermostatic Refrigerant Expansion Valves. The refrigerating effect
12、produced by the evaporation of refrigerant which will pass through the valve under the following specified conditions: 3.1.1 Liquid refrigerant temperature at the valve inlet, C 3.1.2 Saturated evaporator temperature C 3.1.3 Pressure difference across the valve, kPa 3.1.4 Static superheat set point,
13、 C 3.1.5 Superheat change from the set point, C 3.2 Maximum Operating Pressure (MOP). The value at which the valve limits evaporator pressure in kPa. Table C1 defines the recommended nominal values for MOP. 3.5 Published Rating. A statement of the assigned values of those performance characteristics
14、, under stated Rating Conditions, by which a unit may be chosen to fit its application. These values apply to all units of like nominal size and type (identification) produced by the same manufacturer. The term Published Rating includes the rating of all performance characteristics shown on the unit
15、 or published in specifications, advertising or other literature controlled by the manufacturer, at stated Rating Conditions. 3.5.1 Application Rating. A rating based on tests performed at application Rating Conditions (other than Standard Rating Conditions). 3.5.2 Standard Rating. A rating based on
16、 tests performed at Standard Rating Conditions. 3.6 Rating Conditions. Any set of operating conditions under which a single level of performance results and which causes only that level of performance to occur. AHRI STANDARD 751 (SI)2016_ 2 3.6.1 Standard Rating Conditions. Rating conditions used as
17、 the basis of comparison for performance characteristics. 3.7 “Shall“ or “Should“. “Shall“ or “should“ shall be interpreted as follows: 3.7.1 Shall. Where “shall“ or “shall not“ is used for a provision specified, that provision is mandatory if compliance with the standard is claimed. 3.7.2 Should. “
18、Should“ is used to indicate provisions which are not mandatory but which are desirable as good practice. 3.8 Thermostatic Refrigerant Expansion Valve. A controlling device which regulates the flow of volatile refrigerant into an evaporator of a refrigeration system and which is actuated by changes i
19、n evaporator pressure and superheat of the refrigerant gas leaving the evaporator. 3.9 Thermostatic Refrigerant Expansion Valve Pressure Drop. The pressure drop across the valve, which is the net pressure difference between the valve inlet and outlet. 3.10 Thermostatic Refrigerant Expansion Valve Su
20、perheat. The difference between the temperature of the thermal bulb and the dew point temperature corresponding to the refrigerant pressure at the valve outlet, or at the equalizer connection, when provided. 3.10.1 Static Superheat. The superheat at which the manufacturer calibrates or “sets“ the th
21、ermostatic expansion valve. 3.11 Vapor-free (Subcooled) Liquid Refrigerant. Refrigerant which has been cooled below the bubble point temperature for a given pressure. Section 4. Test Requirements 4.1 Testing for Capacity. Thermostatic refrigerant expansion valve ratings shall be based on tests condu
22、cted in accordance with the test procedure identified in ANSI/ASHRAE Standard 17. 4.1.1 Alternative flow test methods may be used provided the results obtained can be confirmed by the test method specified in Section 4.1 within the tolerance specified in Section 5.5 of this Standard. Section 5. Rati
23、ng Requirements 5.1 Published Capacity Ratings. Published capacity ratings shall consist of Standard Ratings and may include Application Ratings. Such ratings shall be based on tests of valves made for use with the refrigerant specified in the ratings. All Published Ratings shall be based on Vapor-f
24、ree (Subcooled) Liquid Refrigerant entering the Thermostatic Refrigerant Expansion Valve. The tests shall be made in accordance with the test procedure outlined in Section 4 of this standard. 5.1.1 Standard Ratings. Standard Ratings of capacity shall be published for all Standard Rating Conditions,
25、shown in Table 1, falling within the intended range of application of the valve. 5.1.2 Nominal Rating. The nominal rating is the equivalent capacity rating of the valve at the 4C evaporator Standard Rating Condition (See Standard Rating Condition A in Table 1). 5.1.3 Application Ratings. Application
26、 Ratings provide capacities under operating conditions which differ from those in Table 1. Wherever Application Ratings are published or printed, they shall include a statement of conditions at which the ratings apply. 5.2 Interpolation and Extrapolation of Air Test Data. Published capacity ratings
27、shall be based on air-fixture tests made at two or more evaporator dew point temperatures. Air-fixture test data may be extrapolated or interpolated no more than 8C AHRI STANDARD 751 (SI)-2016 3 from test points and only when the same thermostatic charge is used. In the case of R-134a, data may be e
28、xtrapolated a maximum of 14C below the lowest test point in order to obtain a rating at -40C evaporator dew point temperature. 5.3 Superheat Change. Every published capacity rating shall be based on the capacity resulting from a superheat change above the Static Superheat. This superheat change shal
29、l not exceed 4C for any Published Rating unless clearly designated. 5.4 Static Superheat. For purposes of rating, the Static Superheat shall be no less than 1C. 5.5 Maximum Operating Pressure (MOP). The valve cannot be rated above its MOP. 5.6 Tolerance. To comply with this standard, published capac
30、ity ratings shall be based on data obtained in accordance with the provisions of this section, and shall be such that any production Thermostatic Refrigerant Expansion Valve selected at random and tested shall produce not less than 95% of its published rated capacity. Table 1. Standard Rating Condit
31、ions1,2,3 Standard Rating Condition Liquid Temperature (at expansion valve inlet), C Saturated Condensing Temperature (at expansion valve inlet), C Saturated Evaporating Temperature (at expansion valve outlet), C A4 38 43 4 B 38 43 -7 C 38 43 -23 D 38 43 -40 Notes: 1. For recommended MOP for pressur
32、e-limiting type thermostatic refrigerant expansion, refer to Appendix C of this Standard. 2. For recommended standard connection sizes, refer to Appendix D of this Standard. 3. For superheat conditions, refer to Section 5.3 and Section 5.4. 4. This is the nominal rating condition. Section 6. Minimum
33、 Data Requirements for Published Ratings 6.1 Minimum Data Requirements for Published Ratings. As a minimum, Published Ratings shall include all Standard Ratings. All claims to ratings within the scope of this standard shall include the statement “Rated in accordance with AHRI Standard 751 (SI)“. All
34、 claims to ratings outside the scope of this standard shall include the statement “Outside the scope of AHRI Standard 751 (SI)”. Wherever Application Ratings are published or printed, they shall include a statement of the conditions at which the ratings apply. 6.2 Published Capacity Ratings. Capacit
35、y ratings for net refrigerant capacity, W or kW of refrigeration, shall be published along with at least the following pertinent operating conditions: 6.2.1 Refrigerant designation(s) per ANSI/ASHRAE Standard 34 6.2.2 Evaporator dew point temperature, C 6.2.3 Pressure drop across the valve, kPa 6.2.
36、4 Maximum superheat change from set point at which ratings apply, C 6.2.5 Capacity correction factors for liquid temperatures at the valve inlet which differ from the standard value of 37.0C. These correction factors will be calculated based on values from NIST REFPROP (Database 23) refrigerant prop
37、erties. Note: These include corrections for liquid density and refrigerating effect and are based on an average evaporator temperature of -18.0C. AHRI STANDARD 751 (SI)2016_ 4 Section 7. Marking and Nameplate Data 7.1 Nameplate Data. Each Thermostatic Refrigerant Expansion Valve shall display the ma
38、nufacturers name or trade name, model number, and refrigerant designation(s). 7.1.1 Refrigerant Designation. If colors are used to augment refrigerant designation, the colors defined in AHRI Guideline N shall be used. Section 8. Conformance Conditions 8.1 Conformance. While conformance with this sta
39、ndard is voluntary, conformance shall not be claimed or implied for products or equipment within the standards Purpose (Section 1) and Scope (Section 2) unless such product claims meet all of the requirements of the standard and all of the testing and rating requirements are measured and reported in
40、 complete compliance with the standard. Any product that has not met all the requirements of the standard shall not reference, state, or acknowledge the standard in any written, oral, or electronic communication. AHRI STANDARD 751 (SI)-2016 5 APPENDIX A. REFERENCES - NORMATIVE A1 Listed here are all
41、 standards, handbooks and other publications essential to the formation and implementation of the standard. All references in this appendix are considered as part of the standard. A1.1 AHRI Guideline N-2016, Assignment of Refrigerant Container Colors, 2016, Air-Conditioning, Heating and Refrigeratio
42、n Institute, 2111 Wilson Boulevard, Suite 500, Arlington, VA 22201, U.S.A. A1.2 ANSI/ASHRAE Standard 17-2008, Methods of Testing Capacity of Thermostatic Expansion Valves, 2008, American National Standards Institute/American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 25
43、West 43rd Street, 4th Floor, New York, NY 10036, U.S.A./1791 Tullie Circle N.E., Atlanta, GA 30329, U.S.A. A1.3 ANSI/ASHRAE Standard 34-2013, Designation and Safety Classification of Refrigerants, 2013, American National Standards Institute/American Society of Heating, Refrigerating and Air-Conditio
44、ning Engineers, Inc., 25 West 43rd Street, 4th Floor, New York, NY 10036, U.S.A./1791 Tullie Circle N.E., Atlanta, GA 30329, U.S.A. A1.4 ASHRAE Terminology, https:/www.ashrae.org/resources-publications/free-resources/ashrae-terminology, 2014, American Society of Heating, Refrigerating and Air-Condit
45、ioning Engineers, Inc., 1791 Tullie Circle, N.E., Atlanta, GA 30329, U.S.A. A1.5 REFPROP Reference Fluid Thermodynamic and Transport Properties NIST Standard Reference Database 23 Version 9.1, 2013, U.S. Department of Commerce, Technology Administration, National Institute of Standards and Technolog
46、y, Standard Reference Data Program, Gaithersburg, Maryland 20899, U.S.A. APPENDIX B. REFERENCES - INFORMATIVE B1 Listed here are standards, handbooks and other publications which may provide useful information and background but are not considered essential. References in this appendix are not consi
47、dered part of the standard. None. AHRI STANDARD 751 (SI)-2016_ 6 APPENDIX C. RECOMMENDED MOP FOR PRESSURE-LIMITING TYPE THERMOSTATIC REFRIGERANT EXPANSION VALVES - INFORMATIVE Table C1. Recommended MOP for Pressure-Limiting Type Thermostatic Refrigerant Expansion Valves, kPa (gage)1 Refrigerant Air-
48、conditioning Commercial Refrigeration Medium Temperature Commercial Refrigeration Low Temperature R-22 R-134a R-290 R-404A R-407A R-407C R-410A R-507A R-600a 690 380 690 830 690 690 1170 830 380 450 240 450 550 450 450 790 550 240 170 70 170 210 170 170 340 210 70 Note: 1. These are approximate syst
49、em values. They are subject to a recommended tolerance of 35 kPa. AHRI STANDARD 751 (SI)-2016 7 APPENDIX D. RECOMMENDED STANDARD CONNECTION SIZES - INFORMATIVE Table D1. Recommended Standard Connection Sizes1 Capacity, kW Nominal Connection Size, mm (ODF)2 R-134a, R-407A, R-404A, R-507A & R-600a R-22, R-290, R-407C, R-410A Inlet Outlet 1.8 7.0 11 26 35 70 110
