IMPROVEMENTS IN SAFETY AND RELIEF VALVES
Year: 1873

page_text: LETTERS PATENT to Walter Payton, of No. 21, Great George Street,
Westminster, in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN SAFETY AND RELIEF VALVES."
Scaled the 8th July 1873, and dated the 19th February 1873.
PROVISIONAL SPECIFICATION left by the said Walter Payton at the
Office of the Commissioners of Patents, with his Petition, on the
19th February 1873.
I, WALTER PAYTON, of No. 21, Great George Street, Westminster, in
the County of Middlesex, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN SAFETY AND RELIEF VALVES," to be as
follows:-
This Invention relates to the construction and working of safety and
relief valves in such a manner that only a small weight or light spring is
necessary to keep a valve of large area closed; that when the load is
exceeded by the pressure a large area of escape is immediately provided;

page_text: and that the load is pressed by fluid at rest, instead of being acted on
with uncertainty by fluid issuing rapidly, as with ordinary safety and
relief valves. For this purpose I make the main safety or relief valve of
such diameter as is required for free escape, and extend it upwards so
that it can work like a plunger within a cylindrical casing closed at top, 5
the area of this plunger being somewhat greater than that of the valve
opening. Through this valve I provide a small passage, whereby fluid
can flow from the vessel to which the valve is applied into the upper
part of the valve casing. Immediately above the valve seating there are
lateral passages of escape communicating with the atmosphere.
1
At the side of the main valve I provide a small valve, which is loaded
by a weight or spring. A stem projecting down from this valve is
attached to a piston or plunger, the end of which is exposed to the fluid
pressure within the vessel; or the stem of the valve rests on a flexible
diaphragm exposed to the fluid pressure in like manner. Below the 1
small loaded valve, and above the piston or plunger attached to it, or the
diaphragm on which its stem rests, is a passage communicating with the
upper part of the casing of the main valve above described.
The action of this apparatus is as follows:-When the pressure within
the vessel acting on the piston, plunger, or diaphragm of the small valve 2
is not sufficient to overcome the load thereon this small valve remains
closed. The upper part of the main valve casing is thereby kept closed,
and is supplied with fluid by the passage through the main valve, so that
the pressure on the main valve is equalized above and below it, but that
pressure acting on the larger plunger area above keeps the main valve 2
closed. But when the pressure within the vessel is sufficient, by acting
on the piston, plunger, or diaphragm of the small valve to raise that
valve against its load this valve opening allows fluid to escape from the
upper part of the main valve casing which communicates with it faster
than fluid can be supplied to the cavity above the valve by the passage a
through it, and the pressure upwards on the main valve then exceeding
that on the valve plunger downwards the valve is raised from its
seat, and fluid escapes by the lateral openings in the casing. When
sufficient relief has thus been given by the issue of fluid the pressure
on the piston, plunger, or diaphragm of the small valve becoming insuffi- a
cient to resist the load thercon the small valve closes. The upper part
of the casing of the main valve being thus again closed is supplied with

page_text: fluid by the passage through the valve until the pressure above the main
valve, together with the weight of the valve, becomes sufficient to close
the valve in opposition to the pressure on the smaller area below. It
will thus be seen that the opening and closing of the main valve is con-
trolled entirely by the working of the small valve, which being of small
area requires only a light weight or spring to keep it down. Also, as
this valve is raised by excess of pressure on its piston, plunger, or diaph-
ragm at a point where there is no issue of fluid, and consequently no
interchange of velocity and pressure, the load on the valve becomes an
accurate measure of the pressure within the vessel, and thus the action
of the safety or relief apparatus is rendered highly sensitive and capable
of accurate adjustment.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Walter Payton in the Great Seal Patent Office
on the 19th August 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WALTER
PAYTON, of No. 21, Great George Street, Westminster, in the County of
Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Nineteenth day of February, in the
year of our Lord One thousand eight hundred and seventy-three, in
the thirty-sixth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Walter Payton, Her special
license that I, the said Walter Payton, my executors, administrators, and
assigns, or such others as I, the said Walter Payton, my executors,
administrators, and assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN SAFETY AND
RELIEF VALVES," upon the condition (amongst others) that I, the said
Walter Payton, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should par-

page_text: ticularly describe and ascertain the nature of the said Invention, and in
what manner the same was to be performed, and cause the same to be
filed in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Walter Payton, do hereby declare
the nature of the said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement thereof, reference being had to the accompanying
Drawings, and to the figures and letters marked thereon, that is to say :—
This Invention relates to the construction and working of safety and
relief valves in such a manner that only a small weight or light spring is
necessary to keep a valve of large area closed; that when the load is
exceeded by the pressure a large area of escape is immediately provided;
and that the load is pressed by fluid at rest, instead of being acted on
with uncertainty by fluid issuing rapidly, as with ordinary safety and
relief valves. For this purpose I make the main safety or relief valve of
such diameter as is required for free escape, and extend it upwards, so
that it can work like a plunger within a cylindrical casing closed at top,
the area of this plunger being somewhat greater than that of the valve
opening. Through this valve I provide a small passage, whereby fluid
can flow from the vessel to which the valve is applied into the upper
part of the valve casing. Immediately above the valve seating there are
lateral passages of escape communicating with the atmosphere.
At the side of the main valve I provide a small valve, which is loaded
by a weight or spring. A stem projecting down from this valve is
attached to a piston or plunger, the end of which is exposed to the fluid
pressure within the vessel; or the stem of the valve rests on a flexible
diaphragm exposed to the fluid pressure in like manner. Below the
small loaded valve and above the piston or plunger attached to it, or the
diaphragm on which its stem rests, is a passage communicating with the
upper part of the casing of the main valve above described.
The action of this apparatus is as follows:-When the pressure within
the vessel acting on the piston, plunger, or diaphragm of the small valve
is not sufficient to overcome the load thereon, this small valve remains
closed. The upper part of the main valve casing is thereby kept closed,
and is supplied with fluid by the passage through the main valve, so that

page_text: the pressure on the main valve is equalized above and below it, but that
pressure acting on the larger plunger area above keeps the main valve
closed. But when the pressure within the vessel is sufficient by acting
on the piston, plunger, or diaphragm of the small valve to raise that
valve against this load this valve opening allows fluid to escape from the
upper part of the main valve casing which communicates with it faster
than fluid can be supplied to the cavity above the valve by the passago
through it, and the pressure upwards on the main valve then exceeding
that on the valve plunger downwards the valve is raised from its seat
and fluid escapes by the lateral openings in the casing. When sufficient
relief has thus been given by the issue of fluid the pressure on the
piston, plunger, or diaphragm of the small valve becoming insufficient
to resist the load thereon, the small valve closes. The upper part of the
casing of the main valve being thus again closed is supplied with fluid
by the passage through the valve until the pressure above the main
valve, together with the weight of the valve, becomes sufficient to close
the valve in opposition to the pressure on the smaller area below. It
will thus be seen that the opening and closing of the main valve is
controlled entirely by the working of the small valve, which, being of
small area, requires only a light weight or spring to keep it down. Also,
as this valve is raised by excess of pressure on its piston, plunger, or
diaphragm at a point where there is no issue of fluid, and consequently
no interchange of velocity and pressure, the load on the valve becomes
an accurate measure of the pressure within the vessel, and thus the
action of the safety or relief apparatus is rendered highly sensitive and

page_text: means of a lever, as shewn, with an adjustable weight or spring. This
small valve has a stem extending downwards and swelled out at one or
two places, as shewn, so as to work like a piston or plunger in the cylin-
drical hole in the casing to which it is fitted. E, E, are side passages
for the escape of steam when the main valve A lifts. It will be seen
that while the small valve D remains closed the cavity above the valve A
is filled with steam passing into it through the opening C, which steam
presses the piston part of the valve A downwards, while the steam in the
boiler presses it upwards, but as the pressure downwards acts on a greater
area the valve A remains closed. When however the small valve D is
raised by the pressure of steam on the piston end of its stem exceeding
the load upon it, the steam from the cavity above A escapes faster than
that cavity can be supplied by the small passage C, and thus the pressure
upon A downwards is relieved. The pressure upwards then raises the
valve A, and steam escapes past it to the lateral passages E, E, whence
it escapes. When the pressure in the boiler has been thus sufficiently
relieved the small valve D is closed again, the pressure in the cavity
above A becomes again equal or nearly so to that in the boiler, and the
valve A closes.
Fig. 2, Sheet II., represents a vertical section of the improved safety
valve in a somewhat modified form. In this case the upper portion of
the main valve A is formed to take on to an upper valve seat a, so that
the packing of the upper portion may be dispensed with.
Fig. 3, Sheet II., represents a vertical section of another modification,
in which the small valve D, instead of being placed at the side of the
valve case, is seated on the cover, and the enlarged or plunger part of its
stem passes freely through a hole in the large valve A, and is carried
some distance below the valve, so that it may be pressed on by steam
not affected by the velocity of the current escaping by the valve when it
opens.
It is obvious that a like construction is applicable not only to safety
valves for steam boilers, but also generally to safety and relief valves for
vessels containing fluids or liquids under pressure.
Having thus described the nature of my Invention, and in what
manner the same is to be performed, I claim, in the construction of
safety and relief valves the combination of a large valve kept closed by

page_text: the fluid pressure with a small loaded valve so arranged that when the
small valve is opened the pressure which keeps the large valve closed is
relieved, and the large valve is thereupon opened so as to give full
discharge to the fluid, substantially as herein described.
In witness whereof, I, the said Walter Payton, have hereunto set my
hand and seal, this Eighteenth day of August, in the year of our
Lord One thousand eight hundred and seventy-three.
WALTER PAYTON. (L.S.)