Section 12 Diver Lock-Out Compartment

12.1.2 The 24 hour life support duration is to be available down to a maximum depth of 185 metres (600 feet). The Class will wish to review the life support periods at intervals in order that account may be taken of improvements in life support equipment.

12.1.3 The lock-out compartment during final stages of depressurisation may contain high oxygen partial pressures under certain conditions if mask breathing is not used and consequently there is a considerable fire hazard. Consideration should be given to the suitability and safety of electrical equipment provided in the lockout compartment.

12.2.1 Means must be provided both inside the lock-out compartment and in the submersible craft command module or dive control compartment to control and monitor the pressures and the composition of the atmosphere inside the lock-out compartment.

12.3.1 Controlled depressurisation of the diver requires precise control. Systems should be so designed that the lock-out compartment decompression rate can be controlled in accordance with the decompression tables to be used.

12.3.2 Depressurisation from saturated conditions must be controlled from outside the lock-out compartment.

12.3.3 Controls for depressurisation from short dives should be controllable from inside and outside the lock-out compartment, and an override capability should be provided outside to limit internal control.

12.3.4 In autonomous submersibles some form of recompression and storage or dumping must be provided. If stored, care should be taken to avoid gas contamination.

12.4.1 Oxygen storage must be provided for decompression breathing and metabolic make-up.

12.4.2  Pressurisation Gas: Appropriate gas mixtures should be provided in sufficient quantity to pressurise the lock-out compartment as defined by the mission requirements. Gas banks should be divided into at least two separate groups (normal and reserve) for reliability and shall be piped separately to the supply panel in the command module. When lock out submersibles is to be used for protracted diving, it is recommended that consideration should be given to fitting a plug-in facility on the outside of the submersible craft to enable gas to be supplied through an umbilical from the surface.

12.4.3 Emergency Gas: The necessary piping should be provided to enable an emergency supply of breathing gas to be provided at a mask manifold in the lock-out compartment. At least one breathing mask should be provided for each diver. Masks should be readily accessible under emergency conditions.

12.5.1 The lock-out compartment should be equipped with carbon dioxide removal equipment which will maintain the carbon dioxide partial pressure in the compartment at or below 10 mbar.

12.5.2 The CO2 scrubber blower or fan motor should be carefully selected so that spark hazards are minimised.

12.6.1 Adequate chamber heating should be provided to maintain the diver in safe thermal balance at least for the duration of the planned dive time.

12.6.2 Diver heating is to be available for diving work below 50 metres for air diving system and at a depth for saturation diving system and respiratory gas heating is to be available for all diving work below 150 metres.

12.6.3 Insulation of the lock-out compartment to minimise heat loss is recommended. Heat retention is dependent on the type and thickness of the insulation material used and will directly affect the power from the submersible power plant necessary to maintain the required temperature in the lock-out compartment.

12.6.4 It is recommended that thermal suits are carried in the lock-out compartments for use in emergency.

12.7.1 Where practicable provisions should be made to permit control of humidity within acceptable limits where it is planned to decompress the diver within the lock out compartment.

12.8.2 The system shall be fitted with an auxiliary power source so that it can be used in an emergency for the duration of the life support period.

12.8.3 Persons performing advanced first aid shall be offered priority and unimpeded access to telecommunication services with the duty diving doctor or any other competent personnel as may be required.

12.8.4 The layout and design of instrumentation and communication equipment pertaining to control stands shall be guided by ergonomics. Equally, the minimisation of factors such as noise, vibration or any other disturbance should be considered wherever possible

12.9.1 An oxygen analyser is to be fitted. Analysers which are intended to read in per cent volume should have a range 0-100 per cent. Analysers reading in partial pressure should have a range 0-2 Bar absolute. At least one alternative analysis technique or instrument should be provided.

12.9.2 Means of measuring carbon dioxide content should be provided.

12.9.3 A depth indicator must be fitted both in the lock-out compartment and in the command module to provide an accurate reading of the depth in the lock-out compartment.

12.9.4 A depth indicator with double hull shut off valves should be provided in the lock-out compartment to indicate the external water pressure on the compartment.

12.10.1 For short duration diving, water and food should be stored within the lock-out compartment in pressure balanced containers. Sufficient provisions should be included to maintain each diver for a minimum of 24 hours.

12.11.1 The medical lock required by the Regulations is to be provided and be equipped with approved interlock mechanism and be sized to allow introduction to standard CO2 canister.