Davis Submerged Escape Apparatus
Encyclopedia
The Davis Submerged Escape Apparatus (also referred to as DSEA), was an early type of oxygen
rebreather
invented in 1910 by Sir Robert Davis
, head of Siebe Gorman and Co. Ltd.
, inspired by the earlier Fleuss system. While intended primarily as an emergency escape apparatus for Royal Navy
submarine
crews, it was sometimes used for diving
and as an industrial breathing set.
The DSEA rig 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 approx. 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. Opening the cylinder's valve admits oxygen to the bag and charges it to the pressure of the surrounding water.
The canister of CO2 absorbent inside the breathing bag is connected to a mouthpiece by a flexible corrugated tube; breathing is carried out by 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.
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 tank
s 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
. It was also worn by frogmen piloting the Sleeping Beauty
.
The Davis Submerged Escape Apparatus was the first or nearly the first rebreather to be made in quantity.
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
rebreather
Rebreather
A rebreather is a type of breathing set that provides a breathing gas containing oxygen and recycled exhaled gas. This recycling reduces the volume of breathing gas used, making a rebreather lighter and more compact than an open-circuit breathing set for the same duration in environments where...
invented in 1910 by Sir Robert Davis
Robert Davis (inventor)
Sir Robert Henry Davis 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, inspired by the rebreathers that Henry Fleuss patented as of 1876...
, head of Siebe Gorman and Co. Ltd.
Siebe Gorman
Siebe Gorman & Company Ltd was a British company which developed diving equipment and breathing equipment and worked on commercial diving and marine salvage projects...
, inspired by the earlier Fleuss system. While intended primarily as an emergency escape apparatus for Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...
crews, it was sometimes used for diving
Diving
Diving is the sport of jumping or falling into water from a platform or springboard, sometimes while performing acrobatics. Diving is an internationally-recognized sport that is part of the Olympic Games. In addition, unstructured and non-competitive diving is a recreational pastime.Diving is one...
and as an industrial breathing set.
The DSEA rig comprises a rubber breathing/buoyancy bag, which contains a canister of barium hydroxide
Barium hydroxide
Barium hydroxide is the chemical compound with the formula Ba2. Also known as baryta, it is one of the principal compounds of barium. The white granular monohydrate is the usual commercial form.-Preparation:...
to scrub exhaled CO2
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
and, in a pocket at the lower end of the bag, a steel pressure cylinder holding approx. 56 litres of oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
at a pressure of 120 bar. The cylinder is equipped with a control valve and is connected to the breathing bag. Opening the cylinder's valve admits oxygen to the bag and charges it to the pressure of the surrounding water.
The canister of CO2 absorbent inside the breathing bag is connected to a mouthpiece by a flexible corrugated tube; breathing is carried out by 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
Lifejacket
A lifejacket is a type of personal flotation device designed to keep your airway clear of the water whether the wearer is conscious or unconscious...
) by opening the non-return valve and blowing through the mouthpiece.
The usual Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
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
Drogue
A drogue is a device external to the boat, attached to the stern used to slow a boat down in a storm and to keep the hull perpendicular to the waves. The boat will not speed excessively down the slope of a wave and crash into the next one nor will it broach. By slowing the vessel in heavy...
, 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.
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
HMS Poseidon (1929)
HMS Poseidon was a Parthian-class submarine designed and built by Vickers Shipbuilding and Engineering in Barrow-in-Furness for the United Kingdom Royal Navy, launched on 22 August 1929....
in 1931, HMS Thetis
HMS Thetis (N25)
HMS Thetis was a Group 1 T-class submarine of the Royal Navy which served under two names. Under her first identity, HMS Thetis, she commenced sea trials on 4 March 1939. She sank during trials on 1 June 1939 with the loss of 99 lives...
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 tank
DD tank
DD tanks , were a type of amphibious swimming tank developed by the British during the Second World War...
s such as those used during the Normandy landings.
There were instances, mostly during WWII
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, of the DSEA being used for swimming down from the surface, i.e. for early scuba diving
Scuba diving
Scuba diving is a form of underwater diving in which a diver uses a scuba set to breathe underwater....
. It was also worn by frogmen piloting the Sleeping Beauty
Sleeping Beauty (canoe)
The Motorised Submersible Canoe , nicknamed Sleeping Beauty, was built by British Special Operations Executive during World War II as an underwater vehicle for a single frogman to perform clandestine reconnaissance or attacks against enemy vessels.-Design:The MSC was designed by Major Hugh Quentin...
.
The Davis Submerged Escape Apparatus was the first or nearly the first rebreather to be made in quantity.