When talking about active leak detection systems, one can distinguish a pressurized system, in which an inert carrier gas stream flows through the leak detection circuits and a vacuum based system, where one pulls vacuum pressure behind the liner. All liner compartments are connected in a logical and economical manner via tubing to the ammonia analyzer.
In a pressurized system a flow indicator should be installed to detect clogging.
In a vacuum system vacuum pressure exists in the complete leak detection system; the achieved vacuum pressure is a result of the capacity of the vacuum pump and the amount of ambient air leaking in via the tubing connections. It is unavoidable that some ambient air will enter into the system.
Once a clogging does occur somewhere in a section, the part between the clogging and the vacuum pump / ammonia analyzer will remain under vacuum pressure and under detection. However, the part between the atmospheric ball valve and the clogging will rise in pressure until atmospheric pressures has been reached. This allows for a detection of clogging also in a vacuum system as described below …

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