CHAPTER 14 Surface Supplied Mixed Gas Diving Procedures
Change A 14-15
For Nonsaturation Systems. For nonsaturation systems, the diver shall be rapidly
compressed on air to the depth of the dive or to 225 feet, whichever is shallower.
For compressions deeper than 165 feet, remain at depth for 30 minutes. For
compressions to 165 feet and shallower, remain at depth for a minimum of two
hours. Decompress on USN Treatment Table 8 for Deep Blowup (Figure 21-12).
While deeper than 165 feet, a helium oxygen mixture with 16 percent to 21
percent oxygen, if available, may be breathed by mask to reduce narcosis.
For Saturation Systems. For saturation systems, initial rapid compression on air
to 60 fsw, followed by compression on pure helium to the full depth of the dive or
deeper if symptom onset warrants. The diver shall breathe 84% helium/16%
oxygen by mask during the compression (if possible) to avoid the possibility of
hypoxia as a result of gas pocketing in the chamber. Once at the saturation depth,
the length of time spent can be dictated by the circumstances of the diver, but
should not be less than 2 hours. During this 2 hours, treatment gas should be
administered to the diver as outlined in Chapter 15, paragraph 15-23.8.2. The
chamber oxygen partial pressure should be allowed to fall passively to 0.44-0.48
ata. Begin saturation decompression without an upward excursion.
Symptomatic Omitted Decompression. If the diver develops symptoms of
decompression sickness or gas embolism before recompression for omitted
decompression can be accomplished, immediate treatment using the appropriate
oxygen or air recompression table is essential. Guidance for table selection and
use is given in Chapter 21. If the depth of the deepest stop omitted was greater
than 50 fsw and more than 60 minutes of decompression have been missed, use of
Treatment Table 8 for Deep Blowup or saturation treatment is indicated. On Treat-
ment Tables 4 and 8, a 40-50% oxygen balance helium or nitrogen mixture may be
breathed as treatment gas at 165 fsw and shallower. At 60 fsw and shallower, pure
oxygen may be given to the diver as treatment gas. For all treatment gases (HeO2,
N2O2, and O2) a schedule of 25 minutes on gas and 5 minutes on chamber air
should be followed for four cycles. Additional oxygen may be given at 60 fsw and
Table 14-2. Management of Asymptomatic Omitted Decompression
No decompression stops
Within SUR D limits.
Observe on surface for one hour
.Follow SUR D procedure
50 fsw or Shallower
Not within SUR D limits.
Less than 60 minutes
Compress to 60 fsw as fast as pos-
sible, not to exceed 100 fsw/min.
Use Treatment Table 6.
Deeper than 50 fsw
Stops required. Greater
than 60 minutes missed
Compress to depth of dive not to ex-
ceed 225 fsw. Use Treatment Table
For saturation systems: Compress
to depth of dive. Saturate two hours.
Use saturation decompression with-
out an initial upward excursion