Currently, only three HC refrigerants have been approved by the Environmental Protection Agency (EPA) for use in the U.S. Their usage is currently restricted to only new systems and in limited quantities. The approved refrigerants are R-290 (propane), R-600a (isobutene), and R-441A (a blend). New household refrigerators, freezers, and combination refrigerator/freezers may use R-600a and R-441A with a charge restriction of 57 grams or 2.0 ounces. New retail food refrigerators and freezers (self-contained) may use R-290 with a charge restriction of 150 grams or 5.3 ounces.

This group of refrigerants is considered highly flammable. They are classified as A3 by ASHRAE Standard 34 for their toxicity and flammability potential. When working on equipment using this type of refrigerant, technicians need to work safely and will need to make changes as to how they handle and service this equipment.

Safe and Steady

The first step in working safely is to identify the refrigerants being used. Look at the equipment and compressor’s data plate and identify the type of refrigerant being used. The data plates from the cabinet and compressor refrigerant numbers should match. Beware of unauthorized flammable refrigerants and unauthorized system retrofits. Retrofitting is not allowed. If an unauthorized refrigerant is being used, or if a system has been retrofitted to use an HC, a technician should stop all work and notify the equipment owner of this violation.

Before entering any service area, a tech should always turn on a combustible gas monitor to alert him of the potential presence of flammable refrigerants. Do not turn off the monitor until you leave the service area.

Other Concerns

Transportation is also a concern. Flammable refrigerants are classified as Division 2.1 by the DOT (Department of Transportation) and require signage and placarding when transporting. There may also be additional regulations imposed by the local jurisdiction which a technician must identify and follow.

The mechanical components used within an operating system may also be a concern. Compressors used with flammable refrigerants generally use an enclosed PTC start relay and a sealed thermal protector. The PTC start relay does not spark like some other start-assist devices. Some compressors may be equipped with current relays but they have been approved for use with HC refrigerants. It is generally best to replace a failed component with an OEM part. This applies not only to the compressor but also to all of the operational components.

Propane and isobutene, when used as refrigerants, have different purity levels than when they are used for other purposes. Use only refrigerant-grade HCs. HC refrigerants do not contain stenching agents, therefore you cannot rely on smell to detect a leak. The stenching agent used in the fuel-grade propane is methyl mercaptan, which has a rotten cabbage odor. Do not attempt to add or use a product that has this agent in a refrigerant system — it will form corrosive by-products and lead to a failed system.

Working safely with HC refrigerants is not tremendously difficult but it does require a slightly different approach than most technicians are accustomed to. Being educated about these products is the key to working smartly and safely around these refrigerants.

Publication date: 3/4/2013