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The United States Department of Transportation Pipeline and Hazardous Materials Safety Administration (“PHMSA”) issued an April 13th letter addressing a request for clarification of the Hazardous Materials Regulations (“HMR”) applicable to exceptions for compressed gases in refrigerating machines and their components.
PHMSA was responding to February 4th correspondence from Helen Walter-Terrinoni of the Air-Conditioning, Heating and Refrigeration Institute (“AHRI”).
AHRI posed certain questions addressed in §§ 173.307(a)(4)(iii) and (v) of the HMR.
AHRI first asked whether the exception provided in § 173.307(a)(4)(iii) would apply to refrigerating machines containing 12 kg or less of a flammable, non-toxic liquefied gas. Examples cited included:
- UN3252, Difluoromethane, 2.1
- UN3161, Liquefied gas, flammable, n.o.s., 2.1
The question was qualified by the note that the units would not be offered or transported by air.
PHMSA responded in the affirmative, stating:
Refrigerating machines and components thereof, containing 12 kg or less of a flammable, non-toxic gas, including a liquefied gas, are not subject to the requirements of the HMR provided they are not offered or transported by aircraft.
AHRI also asked whether the exception provided in § 173.307(a)(4)(v) would apply to refrigerating machines containing 100 g or less of a flammable, non-toxic liquefied gas. The example cited included:
- UN3252, Difluoromethane, 2.1
- UN3161, Liquefied gas, flammable, n.o.s., 2.1
In regard to this question, it was asked whether this would apply regardless of the mode of transportation.
PHMSA replied in the affirmative, stating:
Refrigerating machines and components thereof, containing 100 g or less of a flammable, non-toxic liquefied gas, are not subject to the requirements of the HMR, regardless of the mode of transportation.
A copy of the letter can be downloaded here.
