ASHRAE Journal - February 2020 - 38

FEATURE

Identifying Odorants
Using flammable refrigerants with low GWP in household
refrigerating appliances or air-conditioning equipment
means there must be a way to detect them in case of leaks.
Because R-290/propane (A3) or R-32/difluoromethane (A2L)
are odorless and colorless, they are difficult to detect.
Adding odorants to refrigerants isn't common in the
HVAC&R industry. ASHRAE Research Project RP-1794 (Eric
Fossell, principal investigator; Jensen Hughes, contractor)
focused on identifying odorants from other industries that
can be potential candidates for flammable refrigerants based
on their physical properties, odor and toxicity thresholds and
HVAC&R appliance material compatibility. A literature survey

Technician experience level generally has the most
significant effect on fitting assembly time and success,
although to a lesser extent for the press fittings. Smaller
flare fittings were prone to failure during repeated
freezing and thawing of water on the tube.
Neal Lawrence and Sharat Raj authored the ASHRAE
Research Project Report that was published in December
2019. ASHRAE members can access the report for free at
https://technologyportal.ashrae.org/. More details are

identified 200 possibilities and ultimately winnowed those
down to four: hydrogen sulfide, carbonyl sulfide, trimethylamine and methyl mercaptan. More analysis and testing is
necessary to fully evaluate these candidates for suitability in
refrigerating and air-conditioning systems.
This is the first research project in what will likely be a
series of projects that explore the possibility of introducing odorants into refrigerant systems with compromising
the systems, said Michael Vaughn, P.E., Member ASHRAE,
ASHRAE's manager of research and technical services.
The ASHRAE Research Project Report was published in
March 2019. ASHRAE members can access the report for free
at https://technologyportal.ashrae.org/.

available in the final report.

Conclusion
Future research projects are in various stages of development. For example, the contract has been awarded for
RP-1855, Determination of the Impact of Combustion
Byproducts on the Safe Use of Flammable Fluorinated
Refrigerants, with the project kickoff meeting held in
January 2019.

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ASHRAE JOURNAL

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FEBRUARY 2020

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ASHRAE Journal - February 2020

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