Fine leak detection

Fine Leak Detection—using krypton radioactive gas—a beta and gamma emitter (See Ch. 6, Radiation Safety )... 

Also, materials that come in contact with Kr-85 (e.g., exposed ICs, used pump oil, valves, and 0-rings) are surveyed to ensure they do not emit excessive levels of radiation (e.g., >2 mR/hr) because of residual gas in them. Detailed information on exposures and controls from Kr-85 fine leak detection systems are available in Ref 31. 

Helium-leak detectors, radioactive decay detectors, and interferometer (optical) leak detectors are all capable of fine leak detection. The most commonly used in the biomedical device industry is the helium-leak detector. 

Beilstein Handbook Reference) BRN 0505947 EINECS 200-890-2 HSDB 1611 t-Butyl mercaptan tert-Butanethiol tert-Butyl mercaptan tert-Butylthiol tertiary-Butyl mercaptan. Has skunk-like odor. Used as additive to natural gas for leak detection. Liquid mp = -0.5° bp = 64.3° d = 0.7943 soluble in organic solvents, insoluble in H2O. Lancaster Synthesis Co. Mallinckrodt Inc. Sigma-Aldrich Fine Chem. 

Cumulative Helium Leak Detection (CHLD) is a variation on conventional leak detection that allows for gross and fine leak testing in the same pass and the potential for helium-leak detection at leak rates several orders of magnitude lower than with conventional leak-detection methods. 

Occasionally leaks can also be located or detected by means of chemical reactions which result in a discoloration or by penetration of a dye solution into fine openings. The discoloration of a flame due to halogen gas escaping through leaks was used earlier to locate leaks in solder joints for refrigeration units. 

Fine and gross helium leak testing will detect any marginal or bad seals through which moisture and other contaminants can enter the package. 

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