Normally this stress is 0.25 inches of water column, but is often lifted or lowered as the method calls for. Isolators have to be periodically leak tested to be sure their integrity and prevent escape of the decontamination agent. Leak testing can be done by numerous procedures including force https://tailinscitech.wixsite.com/tailinscitech/post/applications-and-benefits-of-tailin-containment-isolator-for-handling-high-potency-materials