Class B Refrigerants must have toxicity at concentrations below what level based on TLV-TWA data?

Class B refrigerants are defined by their toxicity levels, specifically in relation to the Threshold Limit Value – Time Weighted Average (TLV-TWA) data. For a refrigerant to be classified as Class B, it must exhibit a certain level of toxicity at concentrations that are typically considered safe for extended exposure.

In this case, Class B refrigerants are characterized by having toxicity levels that do not present a risk at concentrations below 400 parts per million (ppm). This threshold indicates that while exposure to these refrigerants can have harmful effects at higher concentrations, they are considered relatively less hazardous compared to Class A refrigerants, which have stricter limits. Therefore, the classification helps HVAC technicians understand and manage the risks associated with the handling and use of different refrigerants in various applications safely.