46 CFR § 197.332 - PVHO - Decompression chambers.
Each decompression chamber must -
(a) Meet the requirements of § 197.328;
(b) Have internal dimensions sufficient to accommodate a diver lying in a horizontal position and another person tending the diver;
(c) Have a capability for ingress and egress of personnel and equipment while the occupants are under pressure;
(d) Have a means of operating all installed man-way locking devices, except disabled shipping dogs, from both sides of a closed hatch;
(e) Have interior illumination sufficient to allow visual observation, diagnosis, and medical treatment of an occupant.
(f) Have one bunk for each two occupants;
(g) Have a capability that allows bunks to be seen over their entire lengths from the exterior;
(h) Have a minimum pressure capability of -
(1) 6 ATA, when used for diving to 300 fsw; or
(2) The maximum depth of the dive, when used for diving operations deeper than 300 fsw, unless a closed bell meeting the requirements of § 197.330(a) (3), (4), and (5) is used;
(i) Have a minimum pressurization rate of 2 ATA per minute to 60 fsw and at least 1 ATA per minute thereafter;
(j) Have a decompression rate of 1 ATA per minute to 33 fsw;
(k) Have an external pressure gage for each pressurized compartment;
(l) Have a capability to supply breathing mixtures at the maximum rate required by each occupant doing heavy work; and
(m) Have a sound-powered headset or telephone as a backup to the communications system required by § 197.328(c) (5) and (6), except when that communications system is a sound-powered system.