The Davis Submerged Escape Apparatus (also referred to as DSEA), was an early type of
oxygen rebreather invented in 1910 by
Sir Robert Davis
Sir Robert Henry Davis (1870 – 1965) was an English inventor and director of the Siebe Gorman company. His main invention was the Davis Submerged Escape Apparatus, an oxygen rebreather that Davis patented for the first time in 1910, inspire ...
, head of
Siebe Gorman and Co. Ltd., inspired by the earlier
Fleuss
Henry Albert Fleuss (13 June 1851 – 6 January 1933) was a pioneering diving engineer, and Master Diver for Siebe, Gorman & Co. of London.
Fleuss was born in Marlborough, Wiltshire in 1851.
In 1878 he was granted a patent which improved rebr ...
system,
and adopted by the
Royal Navy after further development by Davis in 1927. While intended primarily as an emergency escape apparatus for
submarine
A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...
crews, it was soon also used for
diving, being a handy shallow water diving apparatus with a thirty-minute endurance,
and as an
industrial breathing set.
Design
The DSEA rig chiefly addressed the problem of
anoxia threatening a person ascending through water, by providing oxygen; and the associated risk of
lung over-pressure injury as underwater pressure reduces with reducing depth, which it addressed by managing oxygen pressures. It also provided assistance with buoyancy, both in the ascent and after reaching the surface. The risk of
decompression illness due to ascending too fast could be addressed by associated equipment; any other escape requirements, such as means of summoning help once the surface was reached, were not considered.
The apparatus itself comprises a rubber breathing/buoyancy bag, which contains a canister of
barium hydroxide to scrub exhaled
CO2 and, in a pocket at the lower end of the bag, a steel pressure cylinder holding approximately 56 litres of
oxygen at a pressure of 120 bar. The cylinder is equipped with a control valve and is connected to the
breathing bag
A rebreather is a breathing apparatus that absorbs the carbon dioxide of a user's exhaled breath to permit the rebreathing (recycling) of the substantially unused oxygen content, and unused inert content when present, of each breath. Oxygen is ...
. Opening the cylinder's valve admits oxygen to the bag and charges it to the pressure of the surrounding water.
The canister of CO
2 absorbent inside the breathing bag is connected to a mouthpiece by a flexible corrugated tube; breathing is through the mouth only, the nose being closed by a clip. Goggles are also provided as a standard part of the apparatus.
The breathing/buoyancy bag is fitted with a non-return release valve which allows air to escape from the bag as the user ascends towards the surface and the water pressure decreases. The wearer can close this valve on reaching the surface, the air in the breathing/buoyancy bag then serving as a life preserver. If the bag becomes deflated while the wearer is on the surface awaiting rescue, it can be refilled (for use as a
lifejacket) by opening the non-return valve and blowing through the mouthpiece.
The usual
Royal Navy DSEA rig also included an emergency buoyancy bag on the front of the main breathing/buoyancy bag to help keep the wearer afloat after reaching the surface even if he had exhausted the air in the breathing/buoyancy bag. This emergency bag was inflated by an "Oxylet" canister inside it - a small steel oxygen cylinder which was opened by breaking its weakened neck and wrenching sharply.
It also had a speed-retarding
drogue, which was a rubber apron unrolled and held out horizontally by the wearer as he ascended, dramatically reducing his speed of ascent through water resistance to avoid
decompression illness.
Operational service
The Davis Submerged Escape Apparatus was the first or nearly the first rebreather to be made in quantity.
Adopted by the Royal Navy in 1929, DSEA was used with limited success to assist crew members to escape from several sunken submarines, for example
HMS ''Poseidon'' in 1931,
HMS ''Thetis'' in 1939 and
HMS ''Perseus'' in 1941.
A small version of the DSEA, the
Amphibious Tank Escape Apparatus (ATEA) was produced for use by the crews of amphibious
DD tanks such as those used during the
Normandy landings.
There were instances, mostly during
WWII, of the DSEA being used for swimming down from the surface, i.e. for early
scuba diving. In WWII it was also notably used by the Underwater Working Party at Gibraltar led by Lt.
Lionel "Buster" Crabb, and worn at times by frogmen piloting 'Sleeping Beauty'
Motorised Submersible Canoe
The Motorised Submersible Canoe (MSC), nicknamed Sleeping Beauty, was built by the British Special Operations Executive (SOE) during World War II as an underwater vehicle for a single frogman to perform clandestine reconnaissance or attacks ag ...
s.
See also
*
External links
DSEA page at The Rebreather Site
References
{{Authority control
Rebreathers
Submarine rescue equipment
Underwater diving in the United Kingdom