Gasmizer Manual - Submarine Manufacturing and Products Ltd

March 2009
4.1.2 The overall layout of the bell equipment is shown in Fig 1. The main components are
as follows:
1. The back pressure regulator (BPR) loader valve – controls the setting of the back
pressure regulator.
2. Pressure gauge – displays the pressure in the water trap, which is the same as the
pressure in the exhaust umbilical if the isolating valve and SAECO valve are open.
3. Bell scrubbing valve – allows recovery and re-cycling of bell gas.
4. SAECO valve – (Supply Actuated Exhaust Cut-Off valve) - isolates the exhaust
umbilical from negative pressure in the event of a gas supply failure.
5. Exhaust umbilical isolating valve (Diver 1).
6. Water trap – collects any water present in the exhaust umbilical.
7. Water trap drain valve- allows the removal of water from the water trap.
8. Back Pressure regulator (BPR) – regulates the pressure in the exhaust umbilical.
9. Metering valve 1 – associated with the diver tracking system.
10.Metering valve 2 – BPR bleed valve associated with the diver tracking system.
11.Flow meter 1.
12.Flow Meter 2
13.Exhaust umbilical isolating valve (Diver 2).
4.1.3 Gas from the diver exhaust umbilical first enters the exhaust manifold. An inward
relieving relief valve set to lift at 3.5 bar (50 psi) is provided on the umbilical connection to avoid
damage to either the umbilical or the diver equipment if the bell is pressurised with an umbilical
and the diver head gear connected.
4.1.4 Gas then passes through a SAECO valve into the water trap. The function of the
SAECO valve is to isolate the diver umbilical from the negative pressure automatically in the
event of any interruption in the gas supply.
4.1.5 From the water trap, gas passes through a back pressure regulator, the purpose of
which is to control the negative pressure in the diver umbilical to the optimum value, giving
minimum breathing resistance. Note that this back pressure regulator may be automatically
adjusted by the diver tracking system if used to maintain the optimum exhaust pressure as the
diver changes depth. Thus, diver depth is sensed by a diver tracking pneumo, which is
continuously purged by a slow bleed of gas. In this way, the BPR loader valve can maintain the
Back Pressure Regulator at a fixed pressure below diver ambient rather than bell depth. Some
helmet exhaust valves do not require the use of the Diver Tracking System.
4.1.6 From the back pressure regulator, gas passes through the hull stops and check valve
to the external water trap. Each of these components is described in more detail in the
following.
4.1.7 The supply system is completely conventional. The only modification to the existing
supply manifold is the addition of a connection required for the diver tracking system and
SAECO valve which will be described later.
Chap 4 Page 21 of 168 OM002 Rev 5