“21% [of HVAC&R industry experts surveyed] said that issues to do with refrigerants, including …. toxicity were [their] main area of safety concern.”

– AIRAH, Safety in the HVAC&R Industry

Understanding the toxicity profile of all refrigerant options is vital to safety.

Refrigerants are divided into two toxicity groups (ASHRAE Standard 34):

  • Class A: These refrigerants are not toxic at higher concentrations.
  • Class B: These refrigerants are toxic at higher concentrations.

Toxicity levels are determined by two main components: the concentration level that can cause harm and the duration of exposure that can cause harm. Class B refrigerants pose a higher risk at higher concentrations and shorter exposures, and must be handled carefully.

Ammonia is an example of a refrigerant that is considered higher toxicity (Class B). In the instance of an ammonia leak or discharge, vapors are highly toxic and harmful to humans.

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 toxicity considerations and safe use and handling here.