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DAVIS SUBMERGED ESCAPE APPARATUS
Description of the Apparatus
The apparatus consists of an insertion
rubber breathing and buoyancy bag, inside which is arranged a canister
containing a chemical for the absorption of the wearer's exhaled
carbonic acid gas (CO2). In a pocket at the lower extremity
of the bag is carried a steel cylinder containing about 56 litres of
oxygen compressed to 120 atmospheres, the cylinder being provided with a
control valve and connected by a tube to the breathing bag. The opening
of the cylinder valve admits oxygen to the breathing bag and charges it
to a pressure equal to that of the surrounding water at whatever depth
the apparatus is being used.
The
wearer is thus able to breathe in a normal manner.
The
canister of chemical absorbent inside the breathing bag is connected by
means of a flexible corrugated tube to a mouthpiece; breathing is
carried out by the mouth only, the nose being closed by a clip . Goggles
with splinterless glasses are also provided.
In order to conserve as much as possible the supply
of oxygen in the cylinder , means are provided whereby oxygen can be
admitted to the bag from an external source of supply-for example, a
charging manifold connected to a large storage cylinder of oxygen
installed in the compartments of the submarine. These consist of a tube
(H) connected to the bag and provided at its outer end with a non-return
inlet valve . This tube is connected to the external source of oxygen
and the latter is turned on until the bag is filled sufficiently to
enable the wearer to breathe comfortably.
A third and last source of supply is provided in the
shape of two small steel capsules of oxygen called "Oxylets", mounted
inside the breathing bag. These capsules are provided with break-off
necks and the oxygen is released from them by gripping (one at a time)
in the hands (through the breathing bag) and wrenching sharply, so
breaking the neck.
The breathing bag is provided with an automatic
non-return air release valve (K) which allows air to escape from the bag
as the user ascends to the surface and decreasing pressures. A "gag"
device is provided so that the wearer can close this valve on reaching
the surface, thus retaining the air in the breathing bag, the latter
then serving as a lifebelt.
A two-way tap (M) is provided in the mouthpiece. This
is kept closed when the apparatus is not in use, in order to prevent
access of air to the chemicals in the canister. It should be closed when
the wearer reaches the surface, the mouthpiece and noseclip being
removed.
Should the main breathing bag become deflated while
the wearer is floating on the surface, it may be refilled by taking the
mouthpiece into the mouth, opening the cock and blowing into the bag.
The cock should be shut again before the mouthpiece is removed from the
mouth.
The apparatus is provided with an adjustable
neck-strap and with adjustable waist-straps. These straps should be
adjusted by the wearer beforehand to suit himself, so that the apparatus
is always ready for use in emergency without further adjustment.
. The Emergency Buoyancy Bag
. This is a small additional bag formed on the front
of the main breathing bag. lts object is to ensure that the wearer of
the apparatus shall remain afloat on reaching the surface-even if he has
lost all the air from the breathing bag.
The emergency bag is inflated by means of an “Oxylet”
situated inside it, and broken by grasping the metal holder (situated at
the bottom right hand side) and bending this until the copper seal is
broken. The emergency bag should be inflated before leaving the
submarine.
.The Speed-Retarding Vane. This is a rubber
extension, similar to an apron, which should be unrolled and held out by
the wearer in the horizontal position when he is ascending through the
water. The vane set up a considerable resistance tot the wearer’s
passage through the water and greatly retards the speed of his ascent.
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