A Room Integrity test predicts how long fire suppressant agents take to descend to a given level within a protected room without having to discharge the actual suppression system – this is usually 10 minutes for the most popular gases. The room is then sealed, and then a series of tests is undertaken. The blower fan unit is temporarily fixed into the test doorway to pressurise and depressurise the enclosure. NFPA 2001, Standard on Clean Agent Fire Extinguishing Systems, requires that a minimum concentration of 85% of the adjusted minimum design concentration be held at the highest level of combustibles for a minimum period of 10 minutes. This is usually long enough to prevent re-ignition for most deep-seated fires and should provide adequate time for the emergency services to attend and prevent the fire taking hold.