Year: 1893

page_text: Date of Application, 5th June, 1893
Complete Specification Left, 2nd Mar., 1894-Accepted, 21st Apr., 1894
I WALTER COUSENS ALEXANDER of Aucklands in the Borough of Barnstaple
in the County of Devon, Gentleman, do hereby declare the nature of this invention
to be as follows:-
-
In this vent tap the air passage or vent pipe is placed above the passage for the
liquid throughout the whole length of the tap, and not in the middle as in ordinary
vent taps. The air pipe or vent pipe is kept clear of liquid at the spout end by the
admission of air through a small hole in the vent pipe (or in the vent passage
through the cock) by which arrangement the air passage is freed from liquid
leaving the air a free passage into the cask or vessel.
Dated this 3rd day of June 1893.
WALTER C. ALEXANDER.

page_text: When the plug is turned so as to open the tap liquid from the closed vessel, into
which the tap is fixed for the purpose of drawing off its liquid contents, begins to
flow along the shank and out by the spout, until checked by the balancing pressure
of the external air at the lower end of the spout; if the vent peg is now removed
from the vent-hole, there being a partial vacuum in the closed vessel, the pressure
of the external air at the place of such removal (which is aided by the weight of
any liquid that may happen to be present in the vent-hole) drives back into the
closed vessel the liquid contained by the vent-tube; at the same time air under
atmospheric pressure passes along the vent hole and vent tube into the closed
vessel. Some air is thus admitted into the closed vessel, and therefore the
equilibrium at the lower end of the spout is thus destroyed, and the flow of liquid
proceeds from the spout. Further air is admitted as required and the flow of liquid
is continued.
The upward direction of the vent-hole is essential, because by this means the
capillary attraction between any liquid in the vent hole and the material of the tap
is overcome by the atmospheric pressure and the weight of such liquid acting
together.
The passage of liquid from the closed vessel through the strainer holes, being
confined to the lower part of the shank, produces an upward rather than a
downward circulation in the neighbourhood of the shank; this upward circulation
aids the escape of air through the air-holes upwards into the closed vessel.
The spout, being made of tube, has a smooth internal surface, and therefore
offers the least possible resistance to the flow of liquid through it, and thus its
filling is promoted.
The spout having a bore smaller than either the shank or the larger hole through
the plug, the supply of liquid to it is amply provided: then the spout is kept full
and acts as a siphon and draws off sufficient liquid from the closed vessel to produce
the vacuum necessary for the admission of external air through the vent tube, and
to maintain a continuous flow.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what
I claim is —
1. The downward communication of the vent hole with the vent tube.
2. The closing of the vent-hole with some means of opening it at pleasure by use
of a vent peg or otherwise.
3. The position of the air-holes being above that of the strainer holes.
4. The spout being made of tube and smooth inside.
5. The bore of the shank and of the lower hole through the plug being each
larger than that of the spout.
All substantially as and for the purposes hereinbefore set forth.
Doield this Wirst day of Mana 100
WALTER C. ALEXANDER.