Section 3 Gas Storage

3.1.1 Every diving system is to be provided with a permanently installed gas storage plant or suitable space for portable gas containers.

3.1.2 The capacity of the gas storage shall be such that, for all the planned diving operations, a sufficient number and quantity of gas mixtures are available to supply all the compression chambers, diving bells and divers with an adequate quantity of the correct gases at all operating depths and under normal and emergency conditions.

3.1.3 Emergency gas is to be stored separate from the normal supply and must not be opened during normal operation.

3.1.4 Where it is intended to use hydrogen or hydrogen mix gases during diving operations full details of the proposed arrangements for storing, distributing and utilizing these gases should be submitted for consideration taking into account the high flammability of the hydrogen and the special precautions necessary for the safety of personnel involved in the diving operations.

3.1.5 It is to be ensured that gas storage cylinders, and associated valve and piping, are adequately designed against fatigue, as applicable for the proposed dive cycles.

3.2.1 Oxygen bottles are to be stored preferably on the open deck or in separate well ventilated non-hazardous locations a suitable distance from any flammable substances.

3.2.2 Spaces in which oxygen is stored must be separated from the adjoining spaces by bulkheads and decks of Type "A"-60 and must be arranged to facilitate speedy exit in case of danger.

3.2.3 Piping systems containing gases with more than 23 per cent oxygen should be treated as systems containing pure oxygen, and the oxygen should be stored in bottles or pressure vessels exclusively intended for such gases. Where pure oxygen is supplied to a chamber, a separate piping system should be provided.

3.2.4 Gaseous oxygen may be stored at any pressure up to 345 bar.

3.2.5 The oxygen gas cylinder must comply with the specification for the pressure at which it will be used and be suitable for oxygen storage. In addition, the cylinder must be capable of withstanding external pressure up to the collapse depth with zero internal cylinder pressure.

3.2.6 Gas cylinders are to be manufactured in accordance with recognised codes and standards for TPV Regulations.

3.2.7 Oxygen should be stored in at least two independent cylinder sub systems. Each sub-system must be arranged so that a failure, by leakage, of any system will not bleed into any other system.

3.2.8 Each group of cylinders should be piped separately to the submersible craft.

3.2.9 Each oxygen line into a compartment, if connected to a common manifold, should be fitted with a non-return valve.

3.2.10 If a low pressure oxygen system can be pressurised to the maximum cylinder pressure then the low pressure system should be designed and tested to the same cylinder pressure.

3.3.1 Gas cylinders are to be painted in colours in accordance with National Codes of Practice or as per latest IMCA guidance. It is essential that the code in use on any particular submersible be clearly marked on that submersible or in the control cabin of diving chambers. Particular care should be taken with oxygen and air as some codes use black for air and light grey for nitrogen. See Table 4.3.1.

With the addition of the symbol stencilled on the neck.