Helinaut 350 Gas Reclaim Helmet

Suitable to 350 MSW (1148 FSW)

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Helinaut 350 Gas Reclaim BandMask

Suitable to 350 MSW (1148 FSW)

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Gas Reclaim System

The purpose of the Reprocessing Gaspure diver gas recovery system is to recover gas mixtures breathed by divers, reprocess it and deliver it into the supply system. The gas is removed from the helmet or mask as it is exhaled by means of a recovery valve (the Helinaut valve). From there it is passed via the bell to the surface where the gas is scrubbed to remove CO2, filtered to remove moisture and any particulate or biological contaminant, and oxygen is added to give the desired breathing mix. The gas is then compressed and delivered to storage until required for use when it will be delivered to the bell gas supply console.

The system requires a minimum amount of equipment on the bell, so adding negligible weight and taking up little space. No electrical connections are required in the umbilical so there is no possibility of communication interference or electrical hazard underwater. Because the major components are topside, it has been possible to design the system such that it may be serviced while a dive continues.

In addition to recovering divers’ gas, the system may be used to recycle bell gas, thus reducing gas loss due to bell flushing. The system has several levels of safety back-up which will be described later. A conventional demand system is used and, by means of a single action, open or closed circuit operation may be selected. Similarly, the conventional emergency bale-out demand system is available.

Exhaled gas is recovered from the diver by means of a Helinaut valve which may be mounted on a helmet or band-mask. The exhaust umbilical is connected via a Saeco valve (supply actuated exhaust cut-off valve) situated in the bell. Gas then passes via a water trap into a back pressure regulator which controls the pressure in the exhaust umbilical. The bellman can monitor this pressure by means of the gauge shown in the diagram. Gas is then passed to the surface via a non return valve and a second water trap. On surface, the gas enters the reprocessing unit.

Within the reprocessing unit, oxygen is injected into the gas to make up to the correct mix before passing to a gasbag. From the gasbag pressure is increased by means of an electric driven gas booster before returning to the reprocessing unit where CO2 and other impurities are removed. Two scrubber canisters are provided either of which can be replenished while a dive continues. Gas discharged from the reprocessing unit passes first to a volume tank then joins a conventional diver’s demand regulator.

During normal operation, the oxygen used by the diver is replaced by a metered oxygen flow into the system. This oxygen flow together with all other aspects of system operation, may be monitored by the diver supervisor at the control console. In the event of interruption of the gas supply from the topside unit, the supervisor is immediately informed by means of an alarm but the diver’s gas supply is maintained from the Heliox gas bank via regulators first on the make up panel and subsequently on the bell gas supply console.

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