The invention relates tocompleteheating systemsparticularly, but not exclusively, for deep sea divers.

There aremany situations indivingwhere a diver requires different forms of body heating. He may need a heated suit to keep his bodywarm and heated gloves for his hands. He may also need some forrn of heating towarm thebreathing gas as thismay reach temperatureswhich arepainfullycoldfor him to breath in.

Thereareanumber ofdifferentwaysofproviding thevarious ormsof heating required. The diver ¹ sbody can beheatedbymeans ofhotwater orby an electrical suit, as described in copending UK patent application no. (Priorityapplicationno.8626768.) Gloves can alsobeheated electrically or by hot water. Gas for breathing is usually warmed by means of a heat exchanger transferring heat from the exhaled gas to the gas to be inhaled. Many of these systems require differentpower inputs toprovide the required heat. Thus providing a diver with all his heating needs involves a great deal of bulky, complex equipment.

The object of the invention is to provide an efficient, compact, substantially self-contained complete heating system for a diver.

The invention provides a complete heating system for a diver comprising: a) a high frequency power supply; b) a water heater; c) an electrically heated suit connected to the hf power supply; d) water heated gloves supplied front the water heater; and e) ahotwaterbreathinggasheatexchanger supplied f omthewater heater; wherein the hf power supply and the water heater are included in a diver- carried unit.

Preferably the hf power supply is powered by a dc electrical source either at the surface or at a diving bell.

Preferably the water heater in the diver-carried unit comprises an enclosure having a sea water inlet and containing a heating element. Preferably the heating is providedbymeans of electrical current suppliedby

the hf supply passing through the heating element.

Preferably hot water is provided toheat thediver*s glovesbymeans of pipes from the water heater to the gloves. Circulation of thehotwater is preferably effected by movement of thediver'shand in that the action of closing thehand causeswater to egress from thegloveviaexitmeans and the action of relaxing thehand allowstheglovetobereplenishedwithwaterf om the hot water supply. Advantageously water exits from the gloves and is replenished f om the hot water supply repeatedly, to provide continuous heatingforthedive 'shands. .advantageouslytheglovesarefree-flooding and water exits to the surrounding environment. Conveniently non- eturn valves are included in the pipes to prevent cooled water flowing back up the pipes and thus affecting the replenishment cycle. The exit means may be locatedon thewristcuff of theglove. Convenientlywater-tight seals are not essential: a limiteddegree of leakage can be.tolerated and this leakage path from the glove through the cuff into the surroundingwaterprovides the necessary exit means. The cuff should be tight enough to ensure that the least resistance to flow ofwater intotheglove isviathesupplytubesothat coldwater isnotdrawnintotheglove. Inoneformthecuffcanactasatype of non-return valve so that if the supply of hot water is halted, preventing hot water from being replenished in the glove, then the "sucking in" of the glovecausedbyrelaxation ofthehandcausesthecuff itselftobe "sucked in" such that the cuff tightens around the wrist and cold water cannot be drawn into the glove from the surroundings.

Alternativelywater can egress fromthe gloveviaone ormore outlet tubes. Conveniently only one needt»e used. The tubepreferably includes a non-return valve to prevent v/ater returning into the glove. The outlet tube may either lead out into the surrounding water or back to the hotwater supply for reheating. If the second version is used the system can be a closed loop system with the water being recycled around the gloves and the water heater.

Preferably the breathing gas heat exchanger comprises a shroud around the breathing gas inlet to the mask such that hot water is pumped throughthe shroudtoprovideheatingto inhaledgas. Convenientlythiscan be a closed loop system. Alternatively the water used for heating can be allowed to escape and can be replenished from the heater.

The invention will now be described with reference to the accompanying drawing, which is a schematic diagram of a complete heating system according to the invention.

A diver-carried unit 1 includes an hf power supply 2. This is poweredby a dc electrical source (notshown) viaalightweight inputcable3. Thehf supply 2 provides electricitytoheattheelectrical circuitsofa suit 4via anoutputcable5. Thehfpower supply2 alsoprovideselectricitytoa heater which comprises a heating element 6 in a free-flooding enclosure 7. Seawater can enter theenclosure7 viaan inlet opening8. It isthenheated by the element 6 and hot water is passed via tubes 9,10 to heat the diver's gloves 11,12. The tubes 9,10 contain non-return valves 13,14 to prevent cooled water flowing back through the tubes 9,10. The hot water is also passed through a shroud15 around thediving mask (not shown) to provideheat to thebreathing gas. Water ispumped out from the heater bymeans of apu p 16 along a tube 17 to the shroud 15 and then returnedvia a tube18 tothewater heater enclosure 7 and recycled.

Thehigh f equencyelectricallyheated suit described in Applicant ¹ s copending Patent Application is particularly suitable for use in a heating system according to the invention. For clarity, it and a suitable type of glove will now be briefly described.

The heated suit is worn by a diver inside his diving suit and it is heated by means of high frequency electrical current passing through independent wiring circuits distributed over the suit. The power is provided by means of the high frequency power supply. Tne hf power supply must have a high inherent degreeof safety toavoiddanger of electrical shock to thediver. Inductance in the suit is reducedbywiring thecircuitswith pairedwiresandthearrangementofthewiring circuits eliminatesthe risk of a cross-chest electrical current should a wire break or some other fault occur. The hf power supply conveniently operates at about 30 kHz and, with an output of 500W, it can provide sufficient heating even at depths below 450m. It only needs dc inputs of about 24V to 36V, which can easily be providedbybatteries carried onboardadivingbell orsubmersibleaswell as on ships or surface structures. This eliminates any need for large generators and transformers. The suit can be made with a very high safety factor and a lowweight of equipment. Its use reduces thebulk of required

cablesandlowerpowerlevelscanbeusedthanforother typesofheatedsuits.

Gloves that are particularly suitable for use with the system are heated by circulation of the water around the glove by the pumping action caused by movement of the hand. Hot water is fed via tubes f omthe water heater tothegloves. Itenterseachgloveonthebackandcirculatesaround the diver's hand within the glove. Any movement of the diver's hand, and hence of the gloves, causes water to be forced out around the cuffs in the wrist areas ofthegloves. Water is forcedoutwhen for example thehand is clenched, or a tool is gripped and soon. Whenthehand is relaxedthewater thathas been forced out is replaced fromthesourcewithlowestresistanceto flow ie from the tubes from the hot water supply. This occurs naturally while the diver is working. When he is not occupied with his hands, clenchingand unclenching his fistactsasapumping systemtoforcewater out and draw water in. The non-returnvalves present in the feed tubes prevent water being forced back up the tubes. As thegloves are free-flooding they do not requireanysealsbetween theglove interior and thesurroundingwater and any leaks orminor dansge to theglovesdonotaffectthe operation ofthe heating roeans..

Itwill, however, beobvious thatanysuitableheatedsuitandgloves can be used with the invention described.

The system can be made small and compact and, with only one power cable feeding into thediver-carried unit, theequipment is light-weightand does notundulyencumber thediver, whilst it is still abletoprovideallhis heating requirements.