5.1.1 This section outlines potential design faults regarding divers’ gas
supply and the consequences of a primary failure.
5.1.2 The gas supply system to a diver should be designed in such a way that,
in the event of the diver’s umbilical being cut or severed, it should not deprive
any other diver or standby diver of their gas supply.
5.1.3 The gas supply system in a diving bell should be designed in such a way
that, if the main surface to bell umbilical pressure is lost, the emergency bell on
board gas is brought on-line to the diver or divers. This can be done either
manually or automatically, with a safeguard against exhausting back into the main
umbilical.
5.1.4 The gas supply system to the bell standby diver should give the option of
using either unlimited surface gas supply or the independent limited on board gas
supply.
5.1.5 When designing new diving bells or modifying existing bells, consider the
provision of an independent gas supply to each diver and the standby diver.
5.1.6 The breathing gas supply to divers’ masks must be designed in such a way
that if the diver’s umbilical supply fails the gas from the reserve or bailout
cylinder does not exhaust into the sea.
5.1.7 Oxygen systems over 8.0 bar and compressed air systems over 33 bar shall
have slow-opening shut-off valves.
5.1.8 Pressure regulators for breathing gas are to be of proven design and
manufactured to cope with the pressures and volumes that are required to meet the
operational requirement for the diving systems designed requirement.
5.1.9 Wherever possible, the pressure in oxygen lines is to be reduced at the
gas storage facility to a pressure which is still compatible with an adequate gas
supply to the diving system, see also
Pt 5, Ch 3, 4.1 General Safety Requirements 4.1.3(a).