 This is used to transfer medical material, food and specimens into and out of the main chamber while it is under pressure.Most deck decompression chambers are fitted with built in breathing systems (BIBS), which supply an alternative breathing gas to the occupants (usually oxygen), and discharge the exhaled gas outside the chamber, so the chamber gas is not excessively enriched by oxygen, which would cause an unacceptable fire hazard, and require frequent flushing with chamber gas (usually air).A deck decompression chamber is intended for surface decompression and emergency hyperbaric treatment of divers, but can be used for other hyperbaric treatment under the appropriate supervision of hyperbaric medical personnel.