Risk Assessment of Chiller Using Mildly Flammable Refrigerants

－Safety Measures for Acceptable Probability of Fire Accident －

Abstract

The use of Low-GWP refrigerants, R1234ze(E), R1234yf, and R32 are very important measures to reduce the impact of the global warming problem. But the refrigerants have mild flammability characteristics. Since the refrigerants are adopted for water chillers installed in machine rooms and heat pumps on tops, a risk assessment has been executed at the view of mild flammability. As the result, probability of occurrence of fire accident is 3.89x10^-12 cases/unit/year by using reasonable mechanical ventilation systems as safety measure. The value is calculated by using actual accident record of refrigerant leakage and probability of occurrence of ignition sources.