Improvements in Stop Valves.
Year: 1894

page_text: Date of Application, 30th Nov., 1894
Complete Specification Left, 20th Aug., 1895-Accepted, 5th Oct., 1895
PROVISUAAL DE MULTICATION.
Improvements in Stop Valves.
I, CHARLES DAVY, of Whitworth Road, Ranmoor, Sheffield, in the County
of York, Engineer, do hereby declare the nature of this invention to be as
follows:-
:-
My invention relates, mainly, to bydraulic stop valves but is also applicable
to steam stop valves, the valve, in either case, being of the "floating or pilot-
valve type, that is to say comprising a main valve and a pilot-valve seated in the
main valve and through the medium of which the opening of the main valve is
effected.
The main valve is of cylindrical form of two diameters externally and works in
a closed cylinder of corresponding diameters, an annular chamber being provided
around the shouldered portion of the main valve to which pressure superior to
that which the valve is intended to control is admitted for operating the main valve
in the direction of raising it from its seat. The main valve is tubular and the stem
of the pilot valve passes up through a tight joint therein and may be operated by
a piston attached to its upper end. The main valve has lateral orifices connecting the
inlet with the internal cavity of the valve, said cavity in turn communicating through
a relief valve with the closed upper end of the main valve cylinder. This relief
valve closes in the downward direction and by the lifting of the pilot-valve is
opened for the purpose of allowing the fluid above the main valve to escape and so
permit the main valve to be raised by the pressure in the annulus, alone or assisted
by the piston by which the pilot-valve is operated.
The first effect of opening the pilot-valve is to admit the pressure to the under-
side of the valve face, thus partially counterbalancing the normal pressure on the
top of the main valve which pressure, however, continues to prevent the main
valve rising until the relief valve is opened to permit the displacement of the fluid
above the main valve, the rate of flow through the relief valve determining the
speed at which the main valve can be raised. As the rising of the main valve is
dependent on the relief valve being kept open by the pilot-valve, the rising motion
of the main valve cannot in any case exceed that of the pilot-valve since, were it
to do so, the relief valve would close and by preventing the escape of fluid from
above the main valve would arrest the motion of the latter so that it cannot in any
case open prematurely or with undue violence.
The closing of the main valve is effected by forcing the pilot-valve down on to
its seat carrying the inain valve with it, the relief valve opening automatically to
allow the fluid under pressure to return into the space above the main valve.
There may be more than one relief valve and one or more of these valves may
be adapted to remain closed during the lifting and open only during the closing of
the main valve for the purpose of ensuring a sufficiently large area of admission to
the upper end thereof.
Should the pressure in the annulus be deficient or absent, the main valve may be
raised directly by the spindle of the pilot-valve.
Dated this 30th day of November 1894.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.

page_text: Improvements in Stop Valves.
I, CHARLES DAVY, of Whitworth Road, Ranmoor, Sheffield, in the County
of York, 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 hydraulic stop valves in general, and in particular to
hydraulic stop valves used for controlling the high pressures required for operating
heavy machinery. The valve is provided with an auxiliary valve of the "floating
or pilot type, that is to say it comprises a main stop valve and a pilot-valve seated
in the main valve, the opening of the main valve being effected by power which is
permitted to act by the opening of the pilot-valve.
Reference is to be had to the accompanying drawings, forming part of this
Specification, wherein
Figure 1 represents a vertical sectional elevation of the complete valve and
Figure 2 is a detail view of the relief valve.
The body A of the main valve is a piston of two diameters, the part of larger
diameter being at the end opposite the valve face, and it works in a cylinder B
bored of two diameters corresponding to those of the piston, an annular chamber C
being provided around the portion of the main valve body of lesser diameter, to
which annular chamber hydraulic pressure superior to that which the valve is
intended to control is admitted through a pipe c for operating upon the shoulder a
of the main valve body and so moving it in the direction of raising the valve from
its seat D. The pilot-valve E is seated in an orifice in the lower end of the main
valve body which is hollow and is closed at the upper end. The stem e of the pilot-
valve passes up through a stuffing-box joint in the upper end of the main valve body
and may be operated by a hydraulic piston attached to its upper end, or by a hand
lever F, as shewn. The main valve has lateral orifices 7 connecting the inlet G of
the fluid to be controlled with the internal cavity of the valve body, said cavity in
turn communicating with the upper part of the main valve cylinder B, which is
closed, through a relief valve II seated in the upper end of the valve body. This
relief valve H closes in the downward direction and by the lifting of the pilot-
valve E the relief valve in opened for the purpose of allowing the fluid contained in
the upper end of the cylinder B above the main valve to escape and so permit the
main valve to be raised either by the pressure in the annulus C alone or by the
power by which the pilot-valve is operated, or by both means conjointly. The fir
offert al opening the pil-velvet uit the
of the fail to i controlled
through the orifices
and the body of the main valve to the underside of the latter,
thus partially count phalancing the oral pressure of the fluid on the top of the
main valve which fluid being incompressible, continues to prevent the main valve
rising until by the furthering of the plate the roof valve is opened to
permit the passage through it and through the main valve body of the fluid
displaced from above the main valve, the rate of flow through the relief valve
determining the speed at which the main valve can be raised. The lifting of the
relief valve is effected by a disc collar e fixed on the stem of the pilot-valve within
the main valve body coming in contact with the lower end of the stem of the relief
valve which projects inwards through the top of the main valve. As the continued
rising motion of the main valve is dependent on the relief valve being thus kept
open, the main valve cannot sensibly over-run the pilot-valve since, were it to do
so, the relief valve would be closed by the pressure of the fluid confined above the
main valve and by preventing the escape of that fluid the motion of the main valve
would be arrested so that it cannot in any case open prematurely or with undue
violence. Should the pressure in the annulus be deficient or absent, the main valve

page_text: may be raised directly by the spindle of the pilot-valve whether operated by powr
or by hand lever as shown. The closing of the main valve is effected by forcing
the pilot-valve down on to its seat, the pilot-valve then carrying the main valve
with it and the relief valve opening automatically to allow the fluid under pressure
within the main valve body to return into the space above the main valve.
There may be a supplementary relief valve or valves, as at h, adapted to remain
closed during the lifting of the main valve and to open only during the closing of
that valve for the purpose of ensuring a sufficient passage for the return of the
fluid to the upper end of the main valve cylinder and a sufficiently rapid closure of
the main valve.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I claim is :-
1. The combination, with a hydraulic stop valve working as a piston of two
diameters in a cylinder closed at the upper end and having a pilot-valve seated
within the hollow body, of an annular chamber between the piston and the cylinder
wherein fluid at higher pressure than that to be controlled acts to open the valve,
and of one or more relief valves permitting the flow of fluid to the closed upper end
of the cylinder and preventing its escape, but adapted to be opened by the motion
of the pilot-valve to permit such escape and allow the fluid pressure in the annulus
to open the main valve under the control of the relief valve, substantially as
specified.
2. The combination, with a hydraulic stop valve working as a piston in a
cylinder closed at the upper end and having a pilot-valve seated within it and
raised by power externally applied, of one or more relief valves seated in the upper
end of the main valve body permitting the flow of fluid to the closed upper end of
the cylinder and preventing its escape but adapted to be opened by the pilot-valve,
substantially as and for the purpose specified.
Dated this 30th day of August 1895.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.