Effect of high humidity on flammability property of a few non-flammable refrigerants

The effect of high humidity on the flammability property was examined in air for non-flammable refrigerant materials of R-410A, R-410B, R-134a, and R-125. The high humidity here means the relative humidity of up to 50% at 60 °C. The measurements were done in a 12 L spherical glass flask following the ASHRAE method. Under the present humidity condition, R-410A, R-410B, and R-134a became flammable, whereas R-125 did not. For the first three samples, the limiting humidity condition to make the gas flammable was determined. In addition, the effect of temperature up to 100 °C on the flammability property was examined for these materials at the relative humidity of 50% corrected for 23 °C. All four samples remained non-flammable under this condition. For comparison, flammability limits of several flammable compounds were also measured under similar conditions.