Improvements in Safety Valves.
Year: 1892

page_text: Date of Application, 20th June, 1892
Complete Specification Left; 24th Jan., 1893-Accepted, 11th Mar., 1893
PROVISIONAL
SPECIFICATION.
Improvements in Safety Valves.
I, ROBERT CHAPMAN ANDERSON, of Castle View House, West Hill, Hastings,
in the County of Sussex, Civil Engineer, do hereby declare the nature of this
invention to be as follows :-
My invention relates to safety valves of the kind described in the Specification
of former Letters Patent granted to me No. 4722 of 1876.
The object of my present invention is to render such a safety-valve more certain
in its action and at the same time to simplify the construction thereof.
According to my present invention, the valve proper consists of a steam-tight
piston working vertically in an upper cylinder closed at the top but open at the
bottom. This piston is connected rigidly, by means of a hollow spindle or a tube,
to the valve which it is intended to operate as a safety-valve for relieving the
over pressure of steam or other fluid in the boiler or vessel. This valve, which is
of less diameter than the piston, works in a cylindrical or tubular guide supporting
the cylinder in which the piston works, and this guide is provided with a series of
openings immediately over the bevelled seating of the valve, for the free escape
of the steam or other fluid discharged from the valve when open.
The tube to which both piston and valve are rigidly connected, is carried upwards
and passes through a stuffing-box in the cylinder-cover out into the air, small
openings being provided in the tube immediately over the piston. In a downward
direction this tube is continued for several inches below the valve. Through the
said tube is passed a rigid rod carrying two valves, one of which is normally seated
upon the upper end of the tube which is open to the atmosphere, whilst the other
is adapted to seat itself against the lower end of the tube which is open to the
boiler, but is normally away from its seat. The said rod also carries weights or is
arranged in conjunction with springs corresponding to the pressure at which the
steam or other fluid is fixed to escape.
With this arrangement, the steam or other fluid passes freely from the boiler up
the hollow spindle of the safety-valve and through the openings into the chamber
or space over the piston. The downward pressure thus exerted, by means of the
piston, on the valve, being greater than the upward pressure on the valve (the
piston being of greater diameter than the valve) the valve remains closed. So
soon, however, as the small loaded valve at the top of the spindle tube commences
to rise by reason of the pressure to which it is set being exceeded, the other similar
valve at the bottom of the spindle tube commences to close and shut off com-
munication with the boiler. As a result of this, the downward pressure of steam
over the piston is reduced below that pressing it upwards by reason of the steam
over the piston escaping through the openings in the spindle tube into the
open air.
The safety valve with its piston and hollow spindle (the upper end of which
works through a stuffing-box in the cylinder-cover) then rises just sufficiently to
allow of the escape of as much surplus steam as is then being generated, and at the
same rate of flow as generated.
Dated this 20th den of Lu1000
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in Safety Valves.
I, ROBERT CHAPMAN ANDERSON, of Castle View House, West Hill, Hastings,
in the County of Sussex, Civil Engineer, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
My invention relates to safety-valves of the kind described in the Specification
of former Letters Patent granted to me No. 4722 of 1876.
The object of my present invention is to render such a safety-valve more
certain in its action and at the same time to simplify the construction thereof.
According to my present invention I provide a steam-tight piston working
vertically in a cylinder closed at the top but open at the bottom, the said piston
being connected rigidly, by means of a hollow spindle or a tube, to the valve
proper which it is intended to operate as a safety-valve for relieving the over-
pressure of steam or other fluid in a boiler or other vessel. This valve, which is
of less diameter than the piston, works in a cylindrical or tubular guide supporting
the cylinder in which the piston works, the said guide being provided with a series
of openings immediately above the seating of the valve, for the free escape of the
steam or other fluid discharged through the valve when open.
The tube to which both the piston and valve are rigidly connected, is carried
upwards through the cylinder-cover out into the air, small openings being provided
in the tube immediately over the piston. In a downward direction this tube is
continued for several inches below the valve and is open to the boiler. Through
the said tube is passed a rigid rod carrying two valves, one of which is normally
seated upon the upper end of the tube whilst the other is adapted to seat itself
against the lower end of the tube but is normally away from its seat. The said
rod also carries weights or is arranged in conjunction with springs corresponding
to the pressure at which the steam or other fluid is fixed to escape.
To enable my invention to be fully understood I will describe the same by
reference to the accompanying drawings, in which :-
:-
Figure 1 is an elevation of my improved safety-valve; and,
Figure 2 is a central vertical section of the same:
Figure 3 is a sectional view similar to Figure 2 illustrating a modification of my
invention; and,
Figures 4 and 5 are sectional views illustrating other modifications.
Similar letters of reference indicate corresponding parts in the several figures.
a is the cylinder closed at the top by a cover b and open at the bottom, and
c is the cylindrical guide supporting and preferably formed integral with the
cylinder a and having at its lower part the flange d or being otherwise suitably
formed for attaching the valve to a boiler or the like. c, c' are the openings in the
guide e for the escape of the steam.
e is the piston working in the cylinder a, and fis the safety-valve proper which,
when inoperative, rests upon a seat f' in the lower part of the tubular guide c, the
said pistone and valve f being connected (as shewn in Figure 2) to a tube g,
the upper end of which projects through a stuffing-box h in the cover b whilst the
lower end extends downwards sufficiently far to project into the boiler to which
the valve is applied. I may, if desired, arrange that the piston e shall at the edges
of the lower surface rest upon a seating in order to prevent the escape of pressure
past the said piston. In such a case, however, it is necessary to make the piston
adjustable relatively with the valve f
i,j are the two valves in connection with the upper and lower ends respectively
of the said tube g, the said valves being connected by a rod j¹ in such a manner
that, when the upper valve i is upon its seat, the lower valve j is away from its
seat and vice versa.

page_text: k, k are the holes formed in the tube g above the piston e, and is a cap screwed
onto the upper end of the said tube g and containing a spring m, one end of which
bears upon the valve i, whilst the other end bears against a cross-bar n passed
through slots in the said tube, the said cross-bar being acted upon by a hand-nut o
screwed upon the cap I in such a manner that when the said nut o is turned in one
or the other direction the pressure of the spring m upon the valve i will be
increased or diminished to the required extent.
The operation of the valve hereinbefore described is as follows. Assume the
valve to be fixed upon a boiler and the parts to be in the position shewn in
Figure 2; the boiler pressure now acts against the underside of the valve f and
also passes up through the tube g and enters through the holes k, k into the space in
the cylinder a above the piston e wherein as the area of this piston is as herein-
before stated greater than the area of the valve f exposed to the steam pressure,
the downward pressure upon the said piston is greater than the upward pressure
upon the said valve so that the latter is retained upon its seat. The steam which
enters the tube y also presses upon the underside of the valve i but is prevented
from lifting the same until its pressure is greater than the pressure exerted by the
spring m, which pressure can be regulated by the nut o according to the pressure
at which the valve f is to open. When the pressure in the boiler reaches or
slightly exceeds the desired limit, the valve i is lifted, and at the same time the
valve is moved onto its seat whereby the pressure in the cylinder a above the
pistone is free to escape past the valve and through openings p, p formed in the
cap 1, into the atmosphere. Owing to the pressure being thus relieved above
the piston e the pressure upon the underside of the valve f causes the lifting of
the latter sufficiently to allow of the escape of the surplus pressure.
pressure within the boiler is reduced to the desired limit the valve i is again closed
upon its seat at the upper end of the tube g by means of the spring m and the
valve j consequently moved away from its seat, whereby the steam is again allowed
to pass up the tube g and enter through the openings k, k above the cylinder e
in order to overcome the pressure upon the underside of the valve f and close
the same.
When the
As in some cases the employment of a stuffing-box might be considered
objectionable, I have provided the arrangement shewn in Figure 3; in this case
the tube g is firmly connected to the cover b, it being shewn in the drawing as
externally screw-threaded and introduced into a corresponding screw-threaded
opening in the said cover. In this case the piston e and valve fare connected
together by a sleeve q which, with the piston and valve, slides upon the tube g, the
openings k, k in the said tube g being formed close beneath the cover b, as shewn,
in order that as the piston rises the said opening shall not be closed thereby and
furthermore I form upon the top of the said piston e lugs or projections r, r which
come in contact with the upper part of the cover and arrest the movement of the
said piston before the latter has moved sufficiently high to close the said
openings k, k.
I sometimes provide in the cover a supplementary valve acted upon by a
spring and so adjusted that it will only open at a pressure slightly greater than
that required to lift the valve i so that in case the said valve i should stick or
be otherwise rendered inoperative the proper operation of the valve ƒ should not
be interfered with.
In practice I find it advantageous when employing the arrangement of my
invention shewn in Figure 3 to arrange the said supplementary valve upon the
tube g, as shewn in Figure 4, where s indicates this supplementary valve. Normally
this valve is retained upon its seat by a spring t, bearing at its lower end upon a
collar u formed upon the cap and at its upper end against a cross-bar v held in
position by studs w, w and nuts w¹, w¹. Should the valve i properly operate no
movement is imparted to the valve s in case, however, that the said valve i
becomes fixed then the pressure on the underside of the valves would lift the
same in order to allow the escape of the pressure above the piston e.
The

page_text: nuts w¹, w¹ serve, through the medium of the cross-bar v, to adjust the pressure of
the spring upon the valve s.
t
In cases where owing to the quality of the water a deposit or incrustation might
be formed upon the lower valvej and so prevent the same from properly operating,
I advantageously employ the arrangement shewn in Figure 5, wherein the said
valve is represented as being seated at some distance within the tube g. In this
case the valves i and jare preferably seated upon the ends of a supplementary
tube within the tube y, as shewn in the said Figure 5.
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. In a safety-valve the combination with the safety-valve proper of a piston
rigidly connected with the said valve, a tube through the centre of the said valve
and piston, two valves seated in or upon the said tube and connected together in
such a manner that when one is open the other is closed, means for normally
retaining the upper valve of the said connected valves upon its seat and openings
formed in the said tube to allow the boiler pressure to enter into the cylinder or
casing of the valve above the piston, substantially as, and for the purposes,
described.
2. In a safety-valve the valve proper of which is connected to a piston working
in a cylinder and having a central tube, rigidly connecting the said piston and valve
proper to the said tube in such a manner that when the valve operates the tube
moves therewith through a stuffing-box in the cover of the said cylinder,
substantially as described.
3. A safety-valve, the valve proper of which is rigidly connected to a piston
sliding upon a tubular red fixed to the cover of the said cylinder, substantially as
described.
4. The combination with a safety-valve of the kind hereinbefore described of a
supplementary valve substantially as, and for the purpose, described.
5. In a safety-valve of the kind hereinbefore described provided with a
supplementary valve such as is referred to in the preceding claiming clause, the
arrangement of the said supplementary valve upon the rod upon which the safety-
valve proper slides, substantially as described.
6. In a safety-valve of the kind hereinbefore described provided with a piston
and valve upon a central tube, and having connected valves in conjunction with
the said tube, the arrangement whereby the lower of the said valves is seated some
distance within the said tube, substantially as described with reference to Figure 5
of the drawings.
7. The manufacture and use of the improved safety-valve hereinbefore described
and illustrated in the accompanying drawings.
Dated this 24th day of January 1893
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.