Refrigerants and Secondary Coolants
ASHRAE Technical Committee 3.1

Scope of TC 3.1

TC 3.1 is concerned with all properties and functions of refrigerants and secondary coolants, including commercial and experimental materials.


The ASHRAE Handbook is published in a series of four volumes, one of which is revised each year, ensuring that no volume is older than four years.

TC 3.1 is responsible for these chapters in the ASHRAE FUNDAMENTALS Handbook.


Refrigerants are the working fluids in refrigeration, air-conditioning, and heat-pumping systems. They absorb heat from one area, such as an air-conditioned space, and reject it into another, such as outdoors, usually through evaporation and condensation, respectively. These phase changes occur both in absorption and mechanical vapor compression systems, but not in systems operating on a gas cycle using a fluid such as air. (See Chapter 2 for more information on refrigeration cycles.) The design of the refrigeration equipment depends strongly on the selected refrigerant’s properties. Tables 1 and 2 list standard refrigerant designations, some properties, and safety classifications from ASHRAE Standard 34.

Thermophysical Properties of Refrigerants

This chapter presents data for thermodynamic and transport properties of refrigerants, arranged for the occasional user. The refrigerants have a thermodynamic property chart on pressure-enthalpy coordinates with an abbreviated set of tabular data for saturated liquid and vapor on the facing page. In addition, tabular data in the superheated vapor region are given for R-134a to assist students working on compression cycle examples.

Physical Properties of Secondary Refrigerants

This chapter describes physical properties of several secondary coolants and provides information on their use. Additional, less widely used secondary coolants such as ethyl alcohol or potassium formate are not included in this chapter, but their physical properties are summarized in Melinder (2007). Physical property data for nitrate and nitrite salt solutions used for stratified thermal energy storage are presented by Andrepont (2012). The chapter also includes information on corrosion protection. Supplemental information on corrosion inhibition can be found in Chapter 49 of the 2011 ASHRAE Handbook—HVAC Applications and Chapter 13 of the 2010 ASHRAE Handbook—Refrigeration.

The ASHRAE FUNDAMENTALS HANDBOOK may be purchased from the on-line bookstore by clicking on the highlighted text.

Comment on the Handbook: ASHRAE welcomes your comments on the Handbook or a specific Handbook chapter.  To submit a comment about any aspect or part of the Handbook series, you can use the Handbook Comment Form.

Review a Handbook Chapter: To provide your feedback about a specific Handbook chapter, you can answer the brief survey questions on the Handbook Chapter Review Form.


Technical committees develop and sponsor technical sessions at the winter and annual conferences. Information about their future technical program is discussed at each TC meeting and at the TC’s Program Subcommittee meeting

ASHRAE publishes papers and transactions from presentations at its conference events. In addition, ASHRAE records most of the seminar sessions from its conferences on DVD. These DVDs are ideal for use at chapter meetings, in university courses, or company lunch and learns. Products available from the most recent conference may be found here.

Visit the Documents page to find TC 3.1 presentations from early conferences which may be downloaded.


Technical Committees are responsible for identifying research topics, proposing research projects, selecting bidders, and monitoring research projects funded by ASHRAE. Information about their specific research program is discussed at each TC meeting and at the TC’s Research Subcommittee meeting.

TC 3.1 has the following active research projects.


To ensure the validity of flammability safety classifications issued by SSPC34, standard reference data is needed. Tools such as the proposed flammability property database will allow for the development of blends that are properly investigated and classified to meet demanding future needs.


With the flammability test challenges posed by some of the new alternative refrigerants, appropriate test modifications need to be identified, confirmed, and incorporated into the test procedure included in ASHRAE Standard 34. With this, the proper flammability classification will be assigned to further ensure safety for both the individual (upon handling and using) and the environment (with the introduction of new alternative low GWP refrigerants).


ASHRAE writes standards for the purpose of establishing consensus for: 1) methods of test for use in commerce and 2) performance criteria for use as facilitators with which to guide the industry. ASHRAE publishes the following three types of voluntary consensus standards: Method of Measurement or Test (MOT), Standard Design and Standard Practice. ASHRAE does not write rating standards unless a suitable rating standard will not otherwise be available. ASHRAE is accredited by the American National Standards Institute (ANSI) and follows ANSI's requirements for due process and standards development. Standards may be purchased at the ASHRAE Bookstore.

TC 3.1 is cognizant for the following guideline and standards:

ASHRAE Guideline 6: Refrigerant Information Recommended for Product Development and Standards

ANSI/ASHRAE Standard 34: Designation and Safety Classification of Refrigerants

Proposed Standard 177: Method of Test for Measuring Fractionated Compositions of Refrigerant Blends
(TC 3.2 Co-cognizant)

Other Activities

TIP: If MTG involvement add here otherwise leave blank.

TC 3.1 participates on the following multidisciplinary task group:
Lower Global Warming Potential Alternative Refrigerants

MTG.LowGWP is established to coordinate TC/TG/TRG technical activities to help transition the HVAC&R industry to sustainable lower Global Warming Potential (GWP) alternative refrigerants. The MTG will further request participation from US EPA and AHRI. The MTG responsibilities include suggestions for research, development and presentation of technical programs of all types on alternative lower GWP refrigerants, suggestions for Life Cycle Climate Performance (LCCP) systems evaluation for different applications, development of lower GWP solutions for different applications, and a special publication detailing aspects of LCCP applied to the HVAC&R fields.


ASHRAE Technical FAQs are provided as a service to ASHRAE members, users of ASHRAE publications, and the general public. While every effort has been made to ensure their accuracy and reliability, they are advisory and provided for informational purposes only, and in many cases represent only one person’s view. They are not intended and should not be relied on as an official statement of ASHRAE. Technical questions not addressed may be submitted to the ASHRAE Technical Services department at

Where can I find more design information on a new refrigerant? (24)

What research is ASHRAE conducting regarding new refrigerants? (46)

Where can I find information on new refrigerants? (84)