Typically this tension is 0.25 inches of drinking water column, but is usually lifted or lowered as the process calls for. Isolators have to be periodically leak tested to be sure their integrity and prevent escape from the decontamination agent. Leak testing can be carried out by numerous approaches https://www.tumblr.com/tailinscitech/805881091208724480/applications-and-benefits-of-tailin-containment?source=share