2014 AHR EXPO training sessions on hydrocarbon refrigerants organised in anticipation of greater US availability – Part 2

By Silvia Scaldaferri, Feb 12, 2014, 10:54 2 minute reading

An integral part of the 2014 AHR EXPO was a series of free educational programmes, including “Flammable refrigerants - what you need to know”, presented by the Patrick Murphy, Director, Testing and Training at the RSES (Refrigeration Service Engineers Society). The session focused on the proper techniques for handling systems with refrigerants R290 (propane), R600a (isobutene) and R441A (flammable blend).

Worldwide concern about global warming is driving a shift towards low GWP refrigerants, natural refrigerants, such as hydrocarbons. For example, worldwide there are over 80 million domestic refrigerators using hydrocarbons, in addition to several million bottle coolers, chest freezers and commercial refrigerators. With their introduction technician servicing procedures need to change, a key issue being addressed US by RSES through their US training programmes.

Approved flammable refrigerants in the US

Patrick Murphy began his presentation by providing an overview of the hydrocarbon refrigerants approved for use in the US under the EPA SNAP (Environmental Protection Agency’s Significant New Alternatives Policy Program):

  • R-600a and R-441A up to 57g (2.0 ounces) are allowed in new household refrigerators and refrigerator/freezers, and only in equipment constructed following UL250
  • R290 is allowed in new retail food refrigerators /freezers up to150 grams (5.3 ounces), and only in equipment constructed following UL471.
  • No retrofitting is allowed in the US

In general it is the responsibility of the technician working on flammable refrigerants to know the local regulations.

Labelling requirements

According to Murphy it is vital that those appliances refrigerated using hydrocarbons are correctly labelled with a cautionary notice advising of the risk of fire or explosion, and of the fact that a flammable refrigerant is used.

All markings have to be in letters no less than 6.4 mm (1/4”) high, and the refrigerator or freezer must have red Pantone Matching System (PMS) #185 marked pipes, hoses and other devices through which the refrigerant is serviced.

Upper and lower explosion limits

Murphy’s presentation also reviewed the upper explosion limit (UEL) and lower explosion limit (LEL) for the different hydrocarbon refrigerants. These refer to the concentrations of gas or vapour in air capable of producing a flash of fire in the presence of an ignition source. At concentrations above the UEL or below the LEL there will be insufficient fuel to ignite.

The values are as follows:

  • R290: LEL 2.1% and UEL 9.5%
  • R600a: LEL 1.8% and UEL 8.5%
According to Murphy there is currently no field equipment for determining the ignition concentration percentages, and therefore any ignition source must be avoided at all times.

Murphy also emphasised that when servicing any equipment that uses flammable refrigerants it is essential that this be done in a well-ventilated area. What is more, purging must only be done with an inert gas such as nitrogen and only trained and qualified personnel shall braze or solder.


RSES is the leading education, training and certification preparation organisation for HVAC&R professionals. RSES publishes various comprehensive industry training and reference materials in addition to delivering educational programs designed to benefit HVACR professionals at every stage of their careers. The RSES Hydrocarbon Refrigerants training material and certificate includes a Hydrocarbon Refrigerants study guide designed to assist service technicians in understanding the requirements to safely maintain and service systems that utilise flammable refrigerants, including R-290, R-600a and R-441A.


By Silvia Scaldaferri

Feb 12, 2014, 10:54

Related stories

Sign up to our Newsletter

Fill in the details below