Abstract
Albeit the utilization of halogenated hydrocarbons in new devices is suppressed gradually, due to the protection of environment, large amounts of them still remain in existing equipment. It is important for metrology to carry out proper leak measurements of these devices during their service life with traceability to high quality primary standards.
Efficient methods have been developed for vacuum leaks (gas outflow into vacuum) but halogenated hydrocarbons leak out into the atmosphere under real conditions. The design of primary standards that meet this condition is considerably more difficult and they are still rather rare.
This paper gives an insight into the principles used for these standards, which can be classified into two groups: methods sensitive to the gas species and methods insensitive to the gas species.