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Description: This
marker consists of a body with a steel nose at one end, having a central
hole closed by a stopper which forms part of a thin bakelite disc secured to
the nose by screws. The disc is protected during transit and storage by a
nose transit cover held in position by adhesive tape. The tail constitutes a
buoyancy chamber, and a main outlet tube extends between the diaphragm and a
tail cap at the outer end of the tail. The tail cap has a neck closed by a
thin rupture disc, to which is secured a smaller pillar having a ring
attached to it. Two locating pieces, secured to the outside of the body, are
provided to locate a suspension band in position if the marker is to be
carried on a Light Series Bomb carrier. |
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Functioning: When it is
dropped into water, the bakelite disc is broken by impact with the water;
the stopper falls away and the marker rises to float on the surface. Wa-ter
enters the central hole in the nose, and after passing through the gauze
thimble, some of it soaks through the flannel washer, passes through the
small hole in the valve body, and enters the brass tube after soaking
thriugh the flannel washer in the tube. The remainder of the water passes
through the water-inlet tube, percolates through the open-mesh metallic
cylinder and its flannel sheath, and enters the body of the marker. The
brass cap prevents water from passing through the sheath and coming into
direct contact with the calcium phosphide. The water which enters through
the nose reacts with the magnesium-aluminum phosphide and gives off pure
phosphine, which is not spontaneously inflammable. Some water, however, pass
down the main outlet tube while the marker is submerged, and this water
reacts with the calcium phosphide to produce a phosphine which, in contact
with the air, is spontaneously inflammable. The supply of spontaneously
inflammable gas lasts only about three minutes, and the flame is thereaf-ter
maintained by the phosphine envolved from the magnesium-aluminum phosphide
mix-ing with the gaseous oxides of nitrogen given off by the interaction of
the potassium bi-sulphate and the sodium nitrite, which are dissolved by
some of the water which enters through the nose. |
