The industry response to the CFC issue has accelerated the introduction of alternative refrigerants. The entry of new refrigerants in the market and the introduction of new safety classifications have prompted the extensive revision of this standard. Requests for interpretation or proposals for revision of this standard may be addressed to the ASHRAE Manager of Standards.

This standard falls under the ASHRAE Standards Committee classification of a standard method of measurement or test. This standard prescribes a method of testing capacity of thermostatic expansion valves for use in air-conditioning and refrigeration systems. This standard does not specify the test conditions to be used for obtaining the standard rating. That is done in a rating standard developed by the Air-Conditioning and Refrigeration Institute (ARI). The latest edition of ARI Standard 750 is referenced for the test conditions to be used in obtaining standard ratings for thermostatic refrigerant expansion valves.

Due to the current industry situation relative to refrigerants, this standard will refer to ANSI/ASHRAE Standard 15, Safety Code for Mechanical Refrigeration, and ANSI/ ASHRAE Standard 34, Number Designation and Safety Classification of Refrigerants. Previously, Standard 17 referred to three refrigerants used in the industry: R-12, R-22, and R-502. This revision to Standard 17 will reference the broader refrigerant possibilities without specifically naming them. Historically, this document has been published using rational inch-pound (I-P) units as the primary system of units and equivalent International System of Units (Le Systeme International d'Unites) (SI) as the secondary system of units.

However, to conform to latest ASHRAE Metric Policy and the changing international market, this document has been published using rational SI units as the primary system of units and rational I-P units as the secondary system of units. The principal changes made in this revision of this standard were intended to keep the document current with technology and the industry situation, especially with respect to refrigerants. Appendix A has been provided for further information on this subject but is not part of this standard.

Units: Dual