Toxicity
The refrigerant toxicity classification has 400 ppm Occupational Exposure Limit (OEL) as the divide between higher and lower toxicity refrigerants. Most widely used individual substance HFCs (except HFC-245fa), HFOs and HCFOs are classed as low toxicity (Group A), with OELs in the range 400 to 1000 ppm. Category B refrigerants include trans-1,2-dichloroethene and R514A (which contains trans-1,2-dichloroethene) and HFO-1132E (trans-1,2-difluoroethene).
The hydrocarbon refrigerants are classified as low toxicity. ASHRAE 34 and ISO 817 also provide the ATEL (acute-toxicity exposure limit) for refrigerants. This is the maximum recommended refrigerant concentration determined in accordance with the established systems and intended to reduce the risks of acute toxicity hazards to humans in the event of a refrigerant release.
The toxicity charge limit and the flammability charge limit are used, where required according to ISO 5149, to determine the charge limit (Ref: AREA ISO 5149 guide – maximum refrigerant charge limit calculation (AREA Guide)). The maximum acute toxicity exposure level is set by the limit of oxygen deprivation (ODL), which is 140,000ppm (14% v/v).