Fire Safety of 1, 2 and 2l Refrigerants: Myths and Reality

Abstract For many years fire safety measures for refrigerants were based on experimental data on their burning velocity and flammability limits in air. The analysis conducted in the paper and obtained experimental results show that knowledge of the flammability limits and the burning velocities is not enough to ensure the fire safety of the refrigerant. “Low flammable” substances may form explosive mixtures with air in wide range of conditions (initial concentration, pressure, temperature, ignition source (open hydrocarbon flame, hot surface)), even being a part of non-combustible mixture. One of the most underestimated things is an influence of open hydrocarbon flame as ignition source for halogenated substances not just from Class 2L (low flammable), but also from Class 1 (non-flammable). Mixtures of Class 1, 2L and 2 (lower flammable) refrigerants with lubricant oil should be also tested more carefully for their fire and explosion safety. In some cases the danger of “low flammable” substances may be underestimated due to the mismatch between test conditions and real conditions of use. It is also important that due to peculiarities of the process of mixing “low flammable” partially halogenated substances may form explosive mixtures with air at any mass of partially halogenated substance – the influence of mass factor must be also estimated more carefully.