CHAPTER 10 Nitrogen-Oxygen Diving Operations
Change A 10-5
Special Procedures. In the event there is a switch to air during the NITROX
dive, using the divers maximum depth and bottom time follow the U.S. Navy Air
Decompression Table for the actual depth of the dive.
Omitted Decompression. In the event that the loss of gas required a direct ascent
to the surface, any decompression requirements must be addressed using the stan-
dard protocols for omitted decompression. For omitted decompression dives
that exceed the maximum depth listed on Table 10-1, the diving supervisor must
rapidly calculate the divers EAD and follow the omitted decompression proce-
dures based on the divers EAD, not his or her actual depth. If time will not permit
this, the diving supervisor can elect to use the divers actual depth and follow the
omitted decompression procedures.
Dives Exceeding the Normal Working Limit. The EAD Table has been developed
to restrict dives with a ppO2 greater than 1.4 ata and limits dive duration based on
CNS oxygen toxicity. Dives exceeding the normal working limits of Table 10-1
require the Commanding Officers authorization and are restricted to surface-
supplied diving equipment only. All Equivalent Air Depths provided below the
normal working limit line have the maximum allowable exposure time listed
alongside. This is the maximum time a diver can safely spend at that depth and
avoid CNS oxygen toxicity. Repetitive dives are not authorized when exceeding
the normal working limits of Table 10-1.
NITROX REPETITIVE DIVING
Repetitive diving is possible when using NITROX or combinations of air and
NITROX. Once the EAD is determined for a specific dive, the Standard Navy Air
Tables are used throughout the dive using the EAD from Table 10-1.
The Residual Nitrogen Timetable for Repetitive Air Dives will be used when
applying the EAD for NITROX dives. Determine the Repetitive Group Designator
for the dive just completed using either Table 9-7, Unlimited/No-Decompression
Limits and Repetitive Group Designation Table for Unlimited/No-Decompression
Air Dives or Table 9-8, U.S. Navy Standard Air Decompression Table.
Enter Table 9-7, Residual Nitrogen Timetable for Repetitive Air Dives, using the
repetitive group designator. If the repetitive dive is an air dive, use Table 9-7 as is.
If the repetitive dive is a NITROX dive, determine the EAD of the repetitive dive
from Table 10-1 and use that depth as the repetitive dive depth.
NITROX DIVE CHARTING
The NITROX Diving Chart (Figure 10-1) should be used for NITROX diving and
filled out as described in Chapter 9. The NITROX chart has additional blocks for
the EAD and the percentage of gas in the NITROX mix.