Pressure Decay Leak Detection involves pressurizing the component or refrigeration circuit with dry air or nitrogen and monitoring for a pressure drop over a preset time period. It is an automatic test suitable for finding gross leaks (in the range of a few ounces of refrigerant per year). Pressure decay should be used as a preliminary test prior to Manual or Automatic Tracer Gas Leak Detection.
Manual and Semi-Automatic Tracer Gas Leak Detection involves the filling of the component or refrigeration circuit with a tracer gas such as helium or nitrogen/hydrogen mix, and then "sniffing" for the tracer gas escaping from a leak using a manually-held probe. The typical leak resolution obtainable is as low as 1 g/year of refrigerant depending on the sniffing time and the operator’s skill. In order not to contaminate the working environment with large quantities of tracer gas, this test is normally performed after a Pressure Decay Test that will detect gross leaks.
Automatic Tracer Gas Detection involves the same principle as the “manual” one except that the sniffing operation is replaced by a fully automatic “go-no go leak test. We must stress that the automatic cycle will detect the presence of a leak, but not its exact location.
