Gasmizer Manual - Submarine Manufacturing and Products Ltd

March 2009
8.8 System Operation at Extreme Depths
8.8.1 Deep Diving Procedure – Depth Greater then 200 msw (650 fsw)
When system operation is proposed at 200 meters and beyond, a number of system
modifications are advised.
These arise principally from the increased pressure drops, which occur around the
system when pumping a gas of increased density.
The main modifications are listed below.
1. To achieve acceptable breathing resistance at depth, the use of the ULTRAFLOW
regulator demand (see Section 3.2.2) is required.
2. The performance of all demand regulators deteriorate if the supply pressure
fluctuates. For this reason, it is desirable to mount a volume tank on the bell connected
into the dive supply umbilical in order to minimise pressure fluctuations during a
breathing cycle.
3. Umbilical diameters should be chosen in accordance with table 8. and all
pipework, from topside to the diver should be inspected to ensure the use of full bore
fittings without any flow restrictions.
4. With these modifications, The Electric Gasmizer system is capable of supporting
two divers to depths of 500 msw and beyond.
The table on page no. 8.3 gives guidelines for sizing umbilical. For more detailed
information or for other applications, contact Divex.
8.8.2 Shallow Diving Procedure – Depth less than 40 msw (130 fsw)
In very shallow diving, users may experience insufficient suction in the exhaust system.
In this case, contact Divex for advice.
Chap 8 Page 93 of 168 OM002 Rev 5