Frequently this stress is 0.25 inches of water column, but may be lifted or lowered as the method needs. Isolators should be periodically leak tested to be sure their integrity and forestall escape from the decontamination agent. Leak testing can be done by various solutions together with tension decay https://medium.com/@tailinscitech/applications-and-benefits-of-tailin-containment-isolator-for-handling-high-potency-materials-8c66a55dbcf7