Gasmizer Manual - Submarine Manufacturing and Products Ltd

March 2009
accordingly. This is accomplished automatically by means of the diver tracking system. The
system is shown schematically in the diagram below.
4.5.2 A 1/8 th inch bore pneumo line is added to the diver umbilical. A slow gas bleed is
drawn from the bell gas supply to this pneumo. Thus, gas bubbles will be seen to emerge
continually from this line at a slow rate. The set-up procedure for this system is described in
Section 4.5.
4.5.3 The loader is, in effect, a modified inward relieving relief valve which controls the set
pressure for the BPR. As suction is first applied to the system, gas will be drawn from the BPR
loader line, reducing the pressure until is reaches the set pressure of the loader when it will lift,
allowing gas to flow to prevent further depressurisation. In this way, a fixed reference pressure
is available for the BPR.
4.5.4 The pressure in the diver pneumo line is applied to a piston (having the same area as
the valve opening) on the bottom of the BPR loader. As the diver changes depth, the change in
pressure in the pneumo line will produce a force on this piston which will in effect change the set
pressure of the loader e.g. as the diver goes deeper, an increased force will be produced,
causing the loader to relieve maintaining a lower pressure in the BPR loader line.
4.5.5 In fact, because of the design of the loader assembly, it maintains a constant
difference in pressure between diver ambient and the BPR reference pressure. In this way once
the BPR loader has been set to give minimum breathing resistance in the Reclaim Valve, it will
adjust the exhaust pressure automatically to compensate for changes in diver depth.
Chap 4 Page 27 of 168 OM002 Rev 5