“The potential for refrigerant release and for sources of ignition to be present is typically 100 to 1000 times greater during service and repair activities than at any other time.”

-AIRAH, Operating Flammable Refrigerant-Based Systems

Knowing which refrigerants are considered highly flammable, approved end-uses, and how to handle them appropriately is vital to safety.

Refrigerants are divided into four flammability groups:

• Class 1: These refrigerants are not flammable.
• Class 2: These refrigerants have a lower flammability.
• Class 2L: These refrigerants have a “lower burning velocity.” This is a new safety classification to describe advanced climate technologies specifically. Refrigerants in this class are often referred to as “mildly flammable.”
• Class 3: These refrigerants are highly flammable.

Acceptable levels of flammability risk depends on the specific end-use. For example, even though new generation automotive refrigerants are classified as “mildly flammable,” significant time and effort has been spent on studies concluding that the use of mildly flammable refrigeration in auto air conditioning is safe. Such refrigerants are quickly becoming standard in new vehicles.

Low- and reduced-GWP mildly flammable refrigerants can also be a good choice, with appropriate mitigation, in large equipment installed and maintained by qualified professional technicians and where codes and standards permit.

Highly flammable refrigerants, such as hydrocarbons, on the other hand, require careful handling and highly trained technicians for servicing, especially when equipment is located in areas with close proximity to people.

According to the Refrigeration Service Engineers Society (RSES), the following guidelines should be followed when working with or around refrigerants:

• Always read the product label and the product Material Safety Data Sheet (MSDS);
• Always use with adequate ventilation. Most fatal accidents involving refrigerant are due to oxygen deprivation;
• Never expose refrigerants to flames, sparks or hot surfaces;
• Never trap liquid refrigerants between valves where there is no pressure relief device. A dirty pressure relief device must be replaced;
• Use an alcohol spray to clean refrigerant sight glasses that have become coated with ice;
• When leak testing a system, use nitrogen for increasing the pressure after the refrigerant is recovered. Use a pressure regulator on the nitrogen cylinder to ensure a safe pressure in the system. The low-side test pressure value listed on the data plate should be used as the maximum pressure applied to the system for leak testing;
• Never use oxygen or compressed air for pressurization—some refrigerants may explode when under pressure and mixed with air; and
• Physicians: Do not use epinephrine to treat overexposure.

Learn more about product safety considerations and safe handling here. Learn more about the risks associated with flammability here.