NFPA enclosure integrity testing is a specialized type of enclosure testing that typically measures the airtightness of rooms within buildings that are protected by clean agent fire suppression systems. This test is normally done during the installation and commissioning of the system and is mandatory under NFPA, ISO, EN and FIA Standards that also require the test is repeated annually if any doubt exists about the airtightness from the previous test. These types of enclosures are typically server rooms containing large amounts of computer and electronic hardware that would be damaged by the more typical water based sprinkler system. The word "clean" refers to the fact that after the suppression system discharges, there is nothing to be cleaned up. The agent merely disperses into the atmosphere.