CHAPTER 14 Surface Supplied Mixed Gas Diving Procedures
Change A 14-9
SURFACE SUPPLIED HELIUM OXYGEN EMERGENCY PROCEDURES
In surface supplied mixed gas diving, specific procedures are used in emergency
situations. The following paragraphs detail these procedures. Other medical/phys-
iological factors that surface supplied mixed gas divers need to consider are
covered in detail in Volume 5. The U.S. Navy Treatment Tables are also presented
in Volume 5.
Bottom Time in Excess of the Table.
In the rare instance of diver entrapment or umbilical fouling, bottom times may
exceed 120 minutes, the longest value shown in the table. When it is foreseen that
bottom time will exceed 120 minutes, immediately contact the Navy Experimental
Diving Unit for advice on which decompression procedure to follow. If advice
cannot be obtained in time:
Decompress the diver using the 120 minute schedule for the deepest depth
Shift to 100 percent oxygen at 40 fsw.
Surface the diver after completing 30 minutes on oxygen at 40 fsw. Oxygen
time at 40 fsw starts when divers are confirmed on oxygen.
Compress the diver to 60 fsw in the chamber as fast as possible not to exceed
Treat the diver on an extended Treatment Table 6 (Table 21-8). Extend Treat-
ment Table 6 for two oxygen breathing periods at 60 fsw (20 minutes on
oxygen, then 5 minutes on air, then 20 minutes on oxygen) and two oxygen
breathing periods at 30 fsw (60 minutes on oxygen, then 15 minutes on air,
then 60 minutes on oxygen).
Loss of Helium Oxygen Supply on the Bottom. Follow this procedure if the
umbilical helium oxygen supply is lost on the bottom:
Shift the diver to the emergency gas system (EGS).
Abort the dive.
Remain on the EGS until arrival at 90 fsw.
At 90 fsw, shift the diver to 50% helium 50% oxygen and complete the decom-
pression as planned.
If the EGS becomes exhausted before 90 fsw is reached, shift the diver to air,
complete decompression to 90 fsw, shift the diver to 50% helium 50% oxygen,
and continue the decompression as planned.