IMPROVEMENTS IN THE CONSTRUCTION OF VALVES
Year: 1881

page_text: LETTERS PATENT to William Askew and Alexander Aird, both of Manchester,
in the County of Lancaster, for an Invention of "IMPROVEMENTS IN THE
CONSTRUCTION OF VALVES."
PROVISIONAL SPECIFICATION left by the said William Askew and Alexander
Aird at the Office of the Commissioners of Patents on the 18th May 1881.
WILLIAM ASKEW and ALEXANDER AIRD, both of Manchester, in the County of
Lancaster. "IMPROVEMENTS IN THE CONSTRUCTION OF VALVES."
Our improved valve is designed principally to be employed as a vacuum valve
to steam cylinders and pipes, to prevent the collapse of the same from atmospheric
pressure when a partial vacuum is created therein cither by the sudden condensation
of the steam therein or otherwise, but it will also act as an ordinary external
valve, and will remain open till all the cold air which is in the cylinder or pipes
has been expelled.
The vacuum valve at present in use for steam cylinders and pipes is so
constructed that it will not open until the internal pressure has been reduced below
the atmospheric pressure (fifteen pounds to the square inch) plus the power of the
spring, because the valve is kept closed by the pressure of the spring; and on the
other hand the valve closes outwards as soon as ever the internal pressure reaches
fifteen pounds minus the power of the spring, and hence the valve closes before all
the cold air has escaped.
These valves also frequently become corroded and much time and trouble are
required in moving them for repairs.
In our improved valve we have a socket or short pipe permanently screwed into
the cylinder of the valve, having a projecting screwed rim and a cross bar
supporting a central boss through which the lower end of the valve spindle works.
The upper end of the valve spindle works through a hole in the centre of a
screwed cap which forms the valve seating and fits onto the screwed rim above
mentioned. There are holes in the side of the cap and a spiral spring is fitted
between the valve and the top of the cap; the tendency of the said spring being
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page_text: always to keep the valve open. Supposing now that the power of the spring is
equal to two pounds, the valve will always open inwards as soon as the pressure is
reduced to two pounds above the atmospheric pressure, so that no vacuum can
ever be formed.
On the other hand the valve being open, on admitting steam to the cylinder or
pipe, the valve will not close till all the cold air has passed out and the internal
pressure has risen to seventeen pounds, or two pounds above the atmospheric
pressure, and consequently the cylinder or pipe will become heated much sooner
than it would do if the valve closed as usual at 13 lbs., or 2 lbs. less than the
atmospheric pressure.
The valve can also readily be removed at any time by merely unscrewing the
сар.
"We are aware that it is not new to have a perforated cap or shield with radial
perforations or apertures screwed on the outside of a vacuum valve by attaching it
to a prolongation above the flange, and therefore we make no claim to the same.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, and of
an Order of the Lord Chancellor, filed by the said William Askew and
Alexander Aird in the Great Seal Patent Office on the 28th February 1882.
WILLIAM ASKEW and ALEXANDER AIRD, both of Manchester, in the County of
Lancaster. "IMPROVEMENTS IN THE CONSTRUCTION OF VALVES."
Our improved valve is designed principally to be employed as a vacuum valve
to steam drying cylinders and pipes, to prevent the collapse of the same from
atmospheric pressure when a partial vacuum is created therein either by the
sudden condensation of the steam therein or otherwise, but it will also act as an
ordinary external valve, and will remain open till the cold air which is in the
cylinders pipes has been expelled.
The vacuum valve at present ordinarily in use for steam cylinders and pipes is
so constructed that it will not open until the internal pressure has been reduced
below the atmospheric pressure (about fifteen pounds to the square inch), plus the
pressure exerted by the spring, because the valve is kept closed by the pressure of
the spring, and on the other hand the valve closes outwards as soon as ever the
internal pressure reaches fifteen pounds, minus the power of the spring, and hence the
valve closes before the cold air has escaped. These valves also frequently become
corroded, and much time and trouble are required in removing them for repairs.
Our improved valve is designed to remedy the above mentioned defects, and is
so constructed that the whole of the valve and its seating can be at any time
removed by simply unscrewing one piece forming the body of the vacuum valve
without interfering with the permanent joint where the socket or short pipe is
screwed into the steam drying cylinder or pipe to which it is to be applied.'
Such being the nature and object of our said Invention, we will now proceed to
describe more in detail the manner in which the same is to be or may be performed
or carried into practical effect, and in order that the same may be clearly
understood we have annexed hereunto a Sheet of Drawings illustrative thereof,
and have marked the same with figures and letters of reference corresponding with
those in the following explanation thereof.
Fig. 1 in the annexed Drawing is a vertical section, and Fig. 2 a plan view of
our improved valve complete; Fig. 3 is a section of the valve seating and bridge
piece; Fig 4 a side elevation of the valve and spring detached, and Fig. 5 a plan
view of the screwed socket.
In our improved valve we have a flanged socket or short pipe a, a, permanently
screwed into the cylinder or pipe as usual, having a projecting screwed rim and at
or near the bottom of the rim a cross bar supporting a central boss or collar b, b,
through which the lower end of the valve spindle c, c, works.
The upper end of the valve spindle c, c, works through a hole in a similar
boss b¹, b, attached to a cross-bar to an outer screwed socket box or ring d, d,
which forms the valve seating and fits onto the screwed rim above mentioned.
There are holes e, c, at the side of the cross bar, and a spiral spring f, f, is fitted
between the valve g, g, and the said boss b', 6', the tendency of the said spring f, f.
being always to keep the valve g, g, open.
Supposing now that the pressure exerted by the spring f, f, is equal to 2 lbs.,
the valve g, g, will always open inwards as soon as the pressure is reduced to 2 lbs.,
above the atmospheric pressure, so that no vacuum can ever be formed.
On the other hand the valve g, g, being open, on admitting steam to the
cylinder or pipe, the valve g, g, will not close till the cold air has passed out, and
the internal pressure has risen to 17 lbs., or 2 lbs. above the atmospheric pressure,
and consequently the cylinder or pipe will become heated much sooner than it would

page_text: do if the valve g, g, closed as usual at 13 lbs., or 2 lbs., less than the atmospheric
pressure.
The valve can also readily be removed at any time by merely unscrewing the
outer socket or ring d, d, which forms the valve seating.
Having now described the nature and object of our said Invention, together
with the manner in which the same is to be or may be performed or carried into
practical effect, we wish it to be understood that we are aware that it is not new
so to apply the spring to a vacuum valve of the ordinary construction, that its
tendency is always to keep the valve open except when closed by pressure from
the inside.
We are also aware that it is not new to have a cap or shield with radial
perforations or apertures screwed onto the outside of a vacuum valve by attaching
it to a prolongation above the flange, and therefore we make no claim to the same,
but what we do claim as new and original is to form or construct the valve
seating in a ring or box, screwed onto or into the projecting rim of the flanged
socket above the flange, so that the whole of the valve and seating can at any time
be removed without disturbing the joint between the flanged socket or short pipe
and the steam drying cylinder or pipe into which it is screwed, substantially in
the manner herein before described and illustrated by the Drawings annexed.
In witness whereof, I, the said Alexander Aird (on behalf of myself and the
said William Askew), have hereunto set my hand and seal, this Twenty
third day of February, in the year of our Lord One thousand eight
hundred and eighty two.
ALEXANDER AIRD. (L.S.)