IMPROVEMENTS IN SAFETY VALVES
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Charles William Collins at the Office
of the Commissioners of Patents on the 30th December 1881.
CHARLES WILLIAM COLLINS of Moss Side Manchester in the County of
Lancaster, Engineer. "IMPROVEMENTS IN SAFETY VALVES."
This Invention relates first to ordinary single beat valves, in which the pressure
is applied by means of springs, and consists in various improved modes of counter-
acting or counterpoising the gradually increasing power of the springs, when acted
upon by the rising of the valves. For each valve, I use a lever working in or on a
bearing fixed to the valve box, the lever in one arrangement being.in contact with
a segment cast or fixed to a swing rod jointed to a standard cast or fixed to the
valve, there being a radius rod for regulating the movement of the swing rod, and
on the lever there is an arm connected by a bolt to the spring, which is coiled like
a volute, or the mainspring of a timepiece.
When the valve is shut, the segment is at its shortest distance from the bearing
or fulcrum of the lever, but when the valve rises for the escape of steam, the
radius rod moves the segment further from the fulcrum, thereby enabling the
valve to act upon increased leverage, and counteract the increasing power of the
spring.
In other arrangements, I use for each valve a spindle communicating with the
lever and valve, there being on the lever an upright, either directly over the valve
spindle or nearer the fulcrum as may be required, and the top of the upright is
jointed or pivotted to the top of a swing frame jointed or pivotted at the bottom
to brackets on the frame which carries the spring.
When the valve is shut, the tops of the upright and swing frame are at their
greatest distance from the fulcrum of the lever, but when the valve rises, they
gradually move inwards and lessen the leverage between the spring and the valve,
thereby counteracting the increasing power of the spring. In a modification of
these arrangements, I connect the top of the upright on the lever to one end of a
volute spring, held at its other end to an arm or standard jointed or fixed to a
bracket cast or fixed to the valve box, and in this case, when the valve rises, the

page_text: top of the upright moves towards the fulcrum of the lever, and so lessens the
leverage between the spring and the valve as to effectually counteract the
increasing power of the spring, and when desired, two springs may be used instead
of one, and also one spring for two valves.
The second part of my Invention relates to double beat valves of the differential
and equilibrium class, each valve having two rims, or sealing surfaces one above
the other, corresponding with two seatings, also one above the other, and cast to
the valve box, the valves being made with the object of employing much lighter
weights or spring pressures than are required for the ordinary single beat valves.
Hitherto, valves of this description have invariably failed, in consequence of the
inability of keeping them tight on account of the unequal expansion and
contraction of the parts, and also in not providing for dead weight valves a simple
and safe counterpoise to counteract the additional pressure of the steam on the two
rims or edges of the valves when they have been lifted from their seatings.
Instead of making the valve with its two rims or edges of one piece of metal, I
make it of two pieces, one piece having a plate which is rivetted or brazed to the
other piece; or I make each piece with a flange, and rivet to them a plate of
metal, the plates in both cases being thin to enable them to yield to any
inequalities arising from unequal expansion and contraction, thereby keeping the
rims or edges of the valve tight upon their seatings; and it is the small area
between the two pieces upon which the steam acts. In another arrangement I
cause the tops of the two pieces of the valve to be fitted loosely to each other, but
leave a space below for the entry of the steam, and over the joint I place one or
more thin flat rings or washers of metal, carbonized card-board, silicated cloth,
asbestos paper, or any other material suitable for sealing the parts; and on these
washers and the before-mentioned thin plates I place two loosely fitting rings or
_ cylinders-for-carrying-the-frames-in-connection with the springs or weights used
for exerting the required pressure on the valves. In many cases, when these valves
are acted upon by springs, it will be found that no counterpoise is required, as the
extra surface of the second rim of the valve enables the steam to act with double
force upon the spring and thereby allow the valve to have sufficient lift; but in
other cases where the valve is required to have a comparatively high-lift and the
pressure is reduced by expansion one or other of the counteracting motions before
described for the single beat valve may be used. In ordinary single beat valves
the area of the edge or scaling surface of the valve is so small in comparison to
the area of its lifting surface that no counterpoise is required, but in each of these
equilibrium or differential valves, where there are two edges or sealing surfaces
and the lifting area comparatively small, the ratio between the lifting area
and the sealing area being as two to one, or three to two, it is evident that when
the valve is lifted and there is no extra pressure or counterpoise exerted upon it
that the valve would remain open until the pressure of the steam in the boiler is
so reduced as to render the valve useless. In one arrangement for weighting one
of these differential valves, I place in the frame at the top of the valve a spindle
having its top in contact with a lever or beam working on a fulcrum in a stationary
pillar, and joint the other end of the lever to a rod carrying a segmental block in
contact with an under-surface of a weighted lever working on a fulcrum in a
standard fixed to the valve box or boiler, it being understood that the weight of
this lever weight is constant, and that it is only by altering the leverage on the
segmental block that the pressure on the valve is regulated, the block being shifted
as required by a radius rod, or by an arm formed on, or connected to the lever.
When the valve is shut, the contact parts of the lever and segmental block are
at their greatest distance from the fulcrum of the lever weight, but when the valve
rises, and the steam is acting with all its force upon the surfaces of the double
rims, the segmental block moves towards the fulcrum to give increased leverage to
the lever weight to balance or counteract the increased pressure, and after the
valve has risen to a certain height, and the steam has lost power by expansion the

page_text: segmental block moves back to give less leverage, and when the steam arrives at
its normal pressure in the boiler, the valve closes, and the segmental block returns
to its first position, and I may here state, that this arrangement of levers may be
used for single beat valves, but in this case, no increased leverage is required, but
a slight diminution when the valve has risen to a certain height. In another
arrangement, I employ for each valve three levers and segmental blocks, and place
the weights on the ends of the levers, the pressure on the valves being regulated
by moving the segmental blocks as before described, and in all the arrangements,
any well-known casing apparatus may be applied worked by hand or power.