Section 5 Oxygen Distribution and Supply

5.1.1 In addition to the requirements of Pt 5, Ch 4, 3 Gas Storage the following shall be complied with.

5.1.2 Materials used in oxygen and oxygen enriched systems are to be compatible with oxygen and due consideration taken of the pressure and velocity of supply. Although nota preferred material the use of stainless steel for piping will be the subject of special consideration.

5.1.3 Before filling oxygen and oxygen enriched systems, all traces of oil and grease are to be removed.

5.1.4 Oxygen supply should be based on a minimum consumption of 30 litres per hour for each man (measured at 20 ^oC).

5.1.5 The oxygen supply is to be free from hydrocarbons or flammables.

5.2.1 The system should be designed to maintain the partial pressure of oxygen within the following physiologically accepted limit: Recommended minimum 150 mm Hg (0.2 bar) and maximum of 0.5 barg for long term exposure.

5.2.2 The oxygen content of any compartment should not normally exceed 23 per cent by volume of the breathing mixture on account of the fire hazard. Suitable control and safety arrangements are to be provided.

5.2.3 If a manual delivery control system is provided for compressed oxygen it should include a cylinder shut-off valve, and a flow controller. A flow indicator may be fitted. A manually operated by pass must be provided.

5.2.4 When an automatic control system is used to maintain the partial pressure of oxygen, manual operation of the system must also be possible. Automatic control systems should include a shut-off valve, a flow controller and a manually operated by pass.

5.2.5 Failure of the automatic control is to be indicated by alarm at control station and manual back up system is to be readily available.

5.3.1 Allowance should be made for any relative movement between an oxygen cylinder and the hull to prevent overstressing of pipes and unions.

5.3.2 Flexible hoses are not to be used unless approved for the purpose.

5.3.3 Flanged pipes should not be used.

5.3.4 Pipes should be secured clear of electrical cables as far as is practicable.

5.3.5 Valves and fittings designed to operate without lubrication should be used as far as practicable. In view of the explosive and contamination risks involved, parts requiring lubrication should be lubricated with approved lubricants only. Fluorocarbon grease is recommended. To lubricate threads, and to assist in obtaining high pressure seals at threads, PTFE tape may be used, but extreme care must be taken that ragged ends of tape do not penetrate the bore of pipes or valves.

5.3.6 All valves for oxygen service must have the manufacturer's warranty that they are suitable for this service at the desired operating pressure of the system.

5.3.7 Pressure regulating devices used in oxygen control systems must be of a design proven in performance and reliability.

5.3.8 Valves, couplings and fittings should be designed such that there is no leakage of water into the oxygen system at the collapse depth.