IMPROVEMENTS TO REFRIGERANT FLAMMABILITY TESTING THROUGH USE OF A POLYCARBONATE APPARATUS

Abstract

There is a new generation of mildly flammable refrigerants that pose unique challenges to flammability limit testing with ASTM E681. This test standard relies on visual observation of flame propagation inside of a spherical glass vessel. The combustion of these refrigerants etches the glass test vessel, making it difficult to properly observe the flame. The current standard specifies the electrodes to be placed vertically in the flame path, hindering the propagation of the flame. The rubber stopper that seals the vessel is prone to leak and also vent before the flame fully propagates, skewing the results of the test. These problems have been addressed through the creation of a polycarbonate testing apparatus that utilizes a weighted rubber stopper and electrodes that penetrate through the side of the vessel. This prototype was tested extensively with R-32, and yield a lower flammability limit of 14.8% when testing with a starting pressure of 91.2 kPa. The polycarbonate prototype proved to be an adequate alternative to the glass flask, and provided solutions to the etching, quenching, and venting issues.