This recommended practice covers a self-contained detection system which is capable of pressurizing a closed system up to 70 psig with halogen (tracer) gas and up to 3500 psig with nitrogen.An external tracer gas supply may be used to increase the capacity of the system. The detector shall be capable of detecting leaks as small as.05 ounce of tracer gas per year, with a system pressure of 70 psig or less.The purpose of this document is to provide a recommended practice for the design of a universal leak detector which will pressurize a closed system with a mixture of inert and tracer gas and provide a probe and detector to indicate location and rate of system leakage with a high degree of accuracy.