A method of introducing a leak detection additive into a closed refrigeration system by a substrate containing the additive. A predetermined amount of the additive is implanted on and absorbed into a host swatch of substrate material which is capable of absorbing and releasing the leak detection additive,...http://www.google.com.hk/patents/US5440919?utm_source=gb-gplus-share專利 US5440919 - Method of introducing leak detection dye into an air conditioning or refrigeration system
