Leaks are detected by a leak-detecting halide torch (see Fig. 5-6). Some torches use alcohol for fuel and produce a colorless flange. When a methyl chloride leak is detected, the flame turns green. A brilliant blue flame is produced when large or stronger concentrations are present. In every instance, the room should be well ventilated when the torch test is made. The combustion of the refrigerant and the flame produces harmful chemicals. If a safe atmosphere is not present, the soap bubble test or oil test should be used to check for leaks.
As mentioned, methyl chloride is hard to detect with the nose or eyes. It does not produce irritating effects. Therefore, some manufacturers add a 1 percent amount of acrolein as a warning agent. Acrolein is a colorless liquid (C3H4O) with a pungent odor.