Normally this tension is 0.25 inches of drinking water column, but could be elevated or reduced as the process calls for. Isolators have to be periodically leak tested to ensure their integrity and prevent escape of the decontamination agent. Leak testing can be carried out by many procedures like https://gunnerdvoah.yourkwikimage.com/2190602/the_definitive_guide_to_compounding_aseptic_isolator