Finding the Right Odorants for Flammable Refrigerants

From eSociety, November 2019

As the HVAC&R industry uses more low-global warming potential (GWP) refrigerants that could be flammable, a leak could create a flammable vapor cloud that if ignited could result in severe consequences. ASHRAE Research Project “1794-RP, White Paper Investigation Relating to the Use of Odorants in Flammable Refrigerants,” provides a detailed literature survey to identify odorants in different industries to help the HVAC&R industry identify suitable odorants to use with flammable refrigerants. 

Eric Forssell, a senior engineer with Jensen Hughes and principal investigator of this research project, discusses the project.

1. What is the significance of this research?

With the use of a flammable refrigerant, there is a possibility of the formation of a flammable vapor cloud resulting from a leak. If this cloud were to be ignited, the consequences could be severe. As the refrigerants are odorless, colorless and refrigeration equipment generally does not include refrigerant loss monitoring, there currently is no provision for a warning of a refrigerant leak. Adding an odorant to the refrigerant is a means of providing a warning.

2. Why is it important to explore this topic now?

With the need to reduce global warming, the switch to using refrigerants that have a lower global warming potential will be increasing. The options for refrigerants with reduced global warming potentials have narrowed to refrigerants that are flammable, ASHRAE Standard 34 classes A2L and A3.

3. What lessons, facts, and/or guidance can an engineer working in the field take away from this research?

There are few easy answers in mitigating the risks involved with flammable refrigerants. With increased use due to their low global warming potentials, all options for mitigating this risk need to be evaluated, including the use of odorants as a means of providing a warning of the development of flammable conditions.

4. How can this research further the industry's knowledge on this topic?

The research conducted identified a large number of odorants that are used in a variety of industries and applications. However, the number of potential candidates narrowed significantly with the requirements for the odorant to remain with the refrigerant throughout the refrigerant loop and not accumulate in the compressor lubricant reservoir. The identified candidates need further evaluation to determine if they can be successfully applied. This further evaluation would concentrate on material compatibility, the amount of odorant required to be added and the reliability of the warning provided.

5. Were there any surprises or unforeseen challenges for you when preparing this research?

The primary challenge or surprise with the research was how quickly the list of candidate odorants narrowed with the need to have a similar boiling point to the candidate refrigerants and to be non-toxic at concentrations above their detection threshold.