CHAPTER 8 — Surface Supplied Air Diving Operations
Change A 8-9
When diving enclosed spaces during ship husbandry operations, the use of an
approved second stage regulator with extended EGS whip 50 to 150 feet in length
is permissible. The manifold block is not used and the diver's umbilical is
connected directly to the low pressure high flow hose from the mask. The scuba
cylinder may be left on the surface or secured at the opening of the enclosed space.
The second stage regulator of the EGS is securely attached to the diver so diver
has immediate access to the EGS regulator in an emergency. If the diving scenario
dictates leaving the EGS topside, adjust the first stage regulator to 150 psig. When
diving in submarine ballast tanks, the mask and umbilical may be left up inside the
ballast tank adjacent to the opening with the extended EGS whip trailing the diver.
An adequately charged scuba cylinder is defined as the pressure that provides
sufficient air to bring the diver to his first decompression stop or the surface for
no-decompression dives. It is assumed that this will give topside personnel enough
time to perform required emergency procedures to restore umbilical air to the
diver. See paragraph 8-2.2.1 for calculating minimum cylinder pressure.
For UWSH or other unique open water dives 60 fsw and shallower, the diving
supervisor may use an ANU approved cylinder designated for EXO BR MS as an
emergency air source.
8-4.5
Flow and Pressure Requirements. The EXO BR MS requires a breathing gas
flow of 1.4 acfm. For dives shallower than 130 fsw, the overbottom pressure shall
be 135-165psi. For those systems which cannot maintain 135 psi overbottom pres-
sure when diving shallower than 60 fsw, 90 psi is permissible. For dives 130-190
fsw, the overbottom pressure shall be 165-225psi. Flow and pressure calculations
are identical to those for the MK21 MOD 1 (see paragraph 8-2.2.3)
8-5
PORTABLE SURFACE-SUPPLIED DIVING SYSTEMS
8-5.1
MK 3 MOD 0 Lightweight Dive System (LWDS). The MK 3 MOD 0 LWDS is a
portable, self-contained, surface-supplied diver life-support system (DLSS). The
MK 3 MOD 0 LWDS can be arranged in three different configurations and may be
deployed pierside or from a variety of support platforms. Each LWDS includes a
control console assembly, volume tank assembly, medium-pressure air compressor
(optional), and stackable compressed-air rack assemblies, each consisting of three
high-pressure composite flasks (0.935 cu ft floodable volume each). Each flask
holds 191 scf of compressed air at 3,000 psi. The MK 3 MOD 0 LWDS provides
sufficient air for two working divers and one standby diver operating at a moder-
ately heavy work rate to a maximum depth of 60 fsw in configuration 1, 130 fsw
in configuration 2, and 190 fsw in configuration 3. The MK 3 MOD 0 will support
diving operations with both UBA MK 20 MOD 0 and UBA MK 21 Mod 1. Set-up
and operating procedures for the LWDS are found in the Operating and Mainte-
nance Instructions for Lightweight Dive System (LWDS) MK 3 MOD 0, SS500-
HK-MMO-010.
8-5.1.1
MK 3 MOD 0 Configuration 1. Air is supplied by a medium-pressure diesel driven
compressor unit supplying primary air to the divers at 18 standard cubic feet per
