2.5.1 Pipe systems should be so designed as to
minimize the noise inside the diving bell and surface compression
chamber during normal operation.
2.5.2 A surface compression chamber should be
equipped with such valves, gauges and other fittings as are necessary
to control and indicate the internal pressure and safe environment
of each compartment from outside the chamber at a centralized position.
2.5.3 Valves, gauges and other fittings should
be provided outside the bell as necessary to control and indicate
the pressure and safe environment within the diving bell. The external
pressure on the diving bell should also be indicated inside the bell.
2.5.4 All pipe penetrations on chambers should
be fitted with two shutoff devices as close to the penetration as
practicable. Where appropriate, one device should be a nonreturn valve.
2.5.5 All surface compression chambers and diving
bells which may be pressurized separately should be fitted with overpressure
alarms or pressure relief valves. If pressure relief valves are fitted,
a quick-operating manual shutoff valve should be installed between
the chamber and the pressure relief valve and should be wired opened
with a frangible wire. This valve should be readily accessible to
the attendant monitoring the operation of the chamber. All other pressure
vessels and bottles should be fitted with a pressure relief device.
2.5.6 Piping systems which may be subjected to
a higher pressure than designed for should be fitted with a pressure
relief device.
2.5.7 All materials used in oxygen systems should
be compatible with oxygen at the working pressure and flow rate.
2.5.8 The use of high-pressure oxygen piping should
be minimized by the fitting of pressure reducing devices, as close
as practicable to the storage bottles.
2.5.9 Flexible hoses, except for umbilicals, should
be reduced to a minimum.
2.5.10 Hoses for oxygen should, as far as practicable,
be of fire-retardant construction.
2.5.11 Piping systems carrying mixed gas or oxygen
under high pressure should not be arranged inside accommodation spaces,
engine rooms or similar compartments.
2.5.12 Exhaust lines should be fitted with an
anti-suction device on the inlet side.
2.5.13 Gases vented from the diving system should
be vented to the open air away from sources of ignition, personnel
or any area where the presence of those gases could be hazardous.
2.5.14 All high-pressure piping should be well
protected against mechanical damage.
2.5.15 Piping systems containing gases with more
than 25 per cent oxygen should be treated as systems containing pure
oxygen.
2.5.16 Oxygen systems with pressure greater than
1.72 bar must have slow opening shutoff valves except pressure boundary
shutoff valves.