21-24 Change A
U.S. Navy Diving ManualVolume 5
Carbon Dioxide Absorbent. CO2 absorbent may be used beyond the expiration
date, when used in a recompression chamber scrubber unit, when the recompres-
sion chamber is equipped with a CO2 monitor. When employed in a
recompression chamber that has no CO2 monitor, CO2 absorbent in an opened but
resealed bucket may be used until the expiration date on the bucket is reached.
Pre-packed, double-bagged canisters shall be labeled with the expiration date from
the absorbent bucket.
Temperature Control. If possible, internal chamber temperature should be main-
tained at a level comfortable to the occupants. Cooling can usually be
accomplished by chamber ventilation in accordance with paragraph 21-5.6.6. If
the chamber is equipped with a heater/chiller unit, temperature control can usually
be maintained for chamber occupant comfort under any external environmental
conditions. Usually, recompression chambers will become hot and must be cooled
continuously. Chambers should always be shaded from direct sunlight. The
maximum durations for chamber occupants will depend on the internal chamber
temperature as listed in Table 21-4. Never commit to a treatment table that will
expose the chamber occupants to greater temperature/time combinations than
listed in Table 21-4 unless qualified medical personnel who can evaluate the trade-
off between the projected heat stress and the anticipated treatment benefit are
consulted. A chamber temperature below 85°F (29.4°C) is always desirable, no
matter which treatment table is used.
Table 21-4. Maximum Permissible Recompression Chamber Exposure Times at
Maximum Tolerance Time
Table 5, 9
Tables 5, 6, 6A, 1A, 9
Internal chamber temperature can be kept considerably below ambient by venting or by using an
installed chiller unit. Internal chamber temperature can be measured using electronic, bimetallic,
alcohol, or liquid crystal thermometers. Never use a mercury thermometer in or around hyperbaric
chambers. Since chamber ventilation will produce temperature swings during ventilation, the above
limits should be used as averages when controlling temperature by ventilation. Always shade
chamber from direct sunlight.