7-1 Sample Scuba Cylinder Data 7-5
8-0 MK 21 MOD 1 Overbottom Pressure Requirements 8-2 |
8-1 Primary Air System Requirements 8-14
8-2 Line-Pull Signals 8-23
9-1 Pneumofathometer Correction Factors 9-2
9-2 Air Decompression Tables Selection Criteria 9-7
9-3 Sea Level Equivalent Depth (fsw) 9-41
9-4 Repetitive Groups Associated with Initial Ascent to Altitude 9-43
9-5 Required Surface Interval Before Ascent to Altitude After Diving 9-53
9-6 Unlimited/No-Decompression Limits and Repetitive Group Designation
Table for Unlimited/No-Decompression Air Dives 9-54
9-7 Residual Nitrogen Timetable for Repetitive Air Dives 9-55
9-8 U.S. Navy Standard Air Decompression Table 9-56
9-8 U.S. Navy Standard Air Decompression Table (Continued) 9-62
9-9 Surface Decompression Table Using Oxygen 9-64
9-10 Surface Decompression Table Using Air 9-67
10-1 Equivalent Air Depth Table 10-4
10-2 Oil-Free Air 10-11
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1. Open-circuit scuba
2. MK 20 MOD 0 surface-supplied gear
3. MK 21 MOD 1 surface-supplied gear
SURFACE-SUPPLIED GEAR (MK 20 MOD 0)
Normal working limit with EGS: 60 fsw
SURFACE-SUPPLIED DEEP-SEA GEAR (MK 21 MOD 1)
Normal working limit with EGS: 190 fsw
Figure 6-13. Air Diving Techniques. A choice of three air diving techniques are available: open circuit scuba, surface-supplied gear (MK 20 MOD 0), and surface-supplied deep-sea gear (MK 21 MOD 1).
6-7.1 Factors to Consider when Selecting the Diving Technique. When selecting the technique to be used for a dive, the following factors must be considered:
Duration and depth of the dive ■ Type of work to be performed Environmental conditions Time constraints
A dive of extended length, even in shallow water, may require an air supply exceeding that which could be provided by scuba. Specific depth limits have been established for each type of diving gear and shall not be exceeded without specific approval of the Chief of Naval Operations in accordance with the OPNAVINST 3150.27 series (see Figure 6-14).
First Stage. High pressure air flows through the orifice of the first stage into the intermediate chamber. When the pressure in the intermediate chamber reaches ambient plus diaphragm balance spring set pressure, the first stage assembly closes.
Second Stage Valve Assembly
Second Stage. Upon inhalation the second stage diaphragm moves inward and the horseshoe lever opens the second stage valve assembly. Intermediate pressure air from the hoses is throttled across the orifice and fills the low pressure chamber to ambient pressure and flow is provided to the diver. Upon exhalation the diaphragm is pushed outward and the second stage in closed. Expired air is dumped from the low pressure chamber to the surrounding water through the exhaust valve.
octopus hose is an alternative and preferred method to accomplish buddy breathing. An octupus is mandatory for standby diver and recommended for all SCUBA divers. The principal disadvantages of the single-hose unit are an increased tendency to freeze up in very cold water and the exhaust of air in front of the diver's mask. While the Navy PMS system provides guidance for repairing and maintaining scuba regulators, the manufacturer's service manual should be followed for specific procedures.
7-18.104.22.168 Full Face Mask. The AGA/Divator full face mask may be used with an approved single-hose first-stage regulator with an octopus, to the maximum approved depth of the regulator, as indicated in the NAVSEA/00C ANU list (Figure 7-2).
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