IMPROVEMENTS IN SAFETY OR RELIEF VALVES AND APPARATUS CONNECTED THEREWITH, CHIEFLY DESIGNED FOR STEAM BOILERS, FIRE ENGINES, AND FORCE PUMPS, OR OTHER APPARATUS CONTAINING FLUID UNDER PRESSURE
Year: 1877

page_text: LETTERS PATENT to James Cadoux Hudson, of Brixton, in the County of
Surrey, for the Invention of "IMPROVEMENTS IN SAFETY OR RELIEF VALVES
AND APPARATUS CONNECTED THEREWITH, CHIEFLY DESIGNED FOR STEAM
BOILERS, FIRE ENGINES, AND FORCE PUMPS, OR OTHER APPARATUS CONTAINING
FLUID UNDER PRESSURE."
Sealed the 16th April 1878, and dated the 19th October 1877.
PROVISIONAL SPECIFICATION left by the said James Cadoux Hudson at the
Office of the Commissioners of Patents on the 19th October 1877.
"IMPROVEMENTS
JAMES CADOUX HUDSON, of Brixton, in the County of Surrey.
IN SAFETY OR RELIEF VALVES AND APPARATUS CONNECTED THEREWITH, CHIEFLY
DESIGNED FOR STEAM BOILERS, FIRE ENGINES, AND FORCE PUMPS, OR OTHER
APPARATUS CONTAINING FLUID UNDER PRESSURE.'
"
The Invention consists in arranging a safety valve having double seats 80
contrived as to allow a large passage of fluid with a low lift, and arranged so that,
although the valve may be of a large diameter, only a part of its area will be
exposed to the pressure of the fluid which it retains; thus admitting the use of a
lighter balance spring or weight than would be required for the usual mushroom
safety valve; also when the fluid it retains reaches a pressure above that to which
the safety valve is loaded, the valve will open and the escaping fluid will act on
the valve in a way to assist the further opening of the valve without an increased
pressure of the fluid; also the degree of this assistance may be regulated. The
valve will return to its seat when the pressure of the fluid is reduced below the
opening pressure.
The safety or relief valve of a steam boiler consists of a valve having double
mitre seats, which are connected by a tube. One seat, which I call the upper
seat, is larger in diameter than the other, which I call the lower seat. The
valve is surrounded by a casing, having double seats to correspond with those
of the valve; there is a free passage between this casing and boiler. When
[Price Gd.1

page_text: the valve is closed the retained steam under pressure surrounds the tube, and acts
on the difference of area of the upper and lower valve seats, and tends to open valve
against resistance of balance weight; when the valve opens the escape from the
upper seat is direct to the atmosphere or escape pipe; the escape from the lower
seat to the atmosphere or escape pipe is into a chamber below valve, and through
the tube connecting the upper and lower valve seats; this passage thro' tube
can be contracted to any desired extent, either by a perforated grating across tube,
or by inserting a ferrule. This will retard the escape of fluid through tube
from lower seat to atmosphere or escape pipe, and a pressure will be exerted on the
area of lower seat of valve, less the opening for escape through grating or ferule in
tube, and will assist the tube in opening. This pressure will increase as the valve
rises, and be governed by the area of escape through grating or ferule.
I can also arrange that the area of escape through tube shall enlarge as the valve
rises, in order to prevent the valve rising past a certain point, by arranging a fixed
cone or other suitably shaped piece projecting up from casing below lower seat into
tube; the area of escape through tube being between inside of tube and outside of
cone. The valve rising will lift the tube from cone, and give a greater area of
escape, as required.
For a fire engine or force pump the valve is arranged in a way similar to that
for a steam boiler; the valve chamber is in connection with the pump head or
delivery chamber.
The escape pipe I prefer to connect to suction chamber of pump; the upper scat
of valve discharges direct into escape pipe; the lower seat discharges through tube
connecting seats of valve; the area of escape through tube may be regulated same
as steam safety valve, and its action is similar. In this arrangement when the
pump is in operation, and water being delivered through hose or pipes, should the
outlets be closed and the pump continue to work, the water will be delivered
through safety valve to suction chamber. When the outlets are again opened the
valve will close, and pump work as before.
The pump may be loaded by a weight or spring balance, or a spiral spring, placed
directly above valve, or with the intervention of a lever or other device; or a
spindle from lower part of valve may pass through a stuffing box fron chamber
below lower seat, and then be connected to a weight, balance, or spiral spring.
Instead of discharging from lower seat to escape pipe through tube of valve I can
form a passage, connecting chamber below lower valve scat and escape pipe to
discharge thro'; this area of discharge may be regulated.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said James Cadoux Hudson in the Great Seal Patent Office on the 18th
April 1878.
JAMES CADOUX HUDSON, of Brixton, in the County of Surrey. "IMPROVEMENTS
IN SAFETY OR RELIEF VALVES AND APPARATUS CONNECTED THEREWITH, CHIEFLY
DESIGNED FOR STEAM BOILERS, FIRE ENGINES, AND FORCE PUMPS, OR OTHER
APPARATUS CONTAINING FLUID UNDER PRESSURE."
These improvements consist in arranging a safety or relief valve, having double
seats, so constructed as to allow a large passage of fluid with a low lift, and so
arranged, that altho the valve may be of large diameter, only a part of its area will
be exposed to the pressure of the fluid which it retains; also, when the fluid it
retains reaches a pressure above that at which the valve is loaded the valve will
open, and the escaping fluid will act on the valve in a way to assist the further
opening of the valve; also, the degree of the assistance may be regulated. The
valve will return to its seat when the pressure of the fluid is reduced below the
opening pressure.
2
In the annexed Drawing Figure 1 is a sectional elevation of the improved safety
valve suitable for steam boilers.
In the Figure (A) is the valve having double mitre faces (B, B',) connected by a
tube (C), and having feathers (D) to top face (B), and a guide (E) to bottom
face (B); orifices (F) are formed in guide (E) to allow escape of steam from
face (B) when valve (A) is open. (G) the valve casing, having double sents to
suit faces on valve (A). The seat to (B) is formed as shown in the body of
valve casing (G); the seat to face (B¹) is formed in a chamber (H) within the
casing (G), and supported by arms (J, J,) from inner side of casing (G); a cone (K)
projects from bottom of chamber (H), and tube (C) of valve (A) is formed in a
conical shape at (L), as shown. The valve is shown loaded by a spring, but a
weight or spring direct or with the intervention of levers, may be used.
The action of the valve is as follows:-When shut the steam from boiler, having
free access within the casing (G), acts on the difference of area of the valve at (M)
and (N), tending to open the valve (A) against the pressure exerted by the load on
valve. When the pressure is overcome the valve opens, and steam escapes from
face (B) direct to atmosphere or escape pipe; steam escapes also from face (B¹) into
chamber (H) below valve, and then passing between external cone (K) and internal
cone (L) ascends tube (C) to atmosphere. The cone (K) or (L) may be made of
any desired shape, so as to throttle the escape of steam from chamber (H) when
valve is opening, and to allow a freer escape when the valve has opened the
desired extent. The throttling of steam in chamber (H) will cause it to exert a
pressure on the area of valve at (N), less the area of opening from internal cone (L)
to tube (C), thus assisting the valve to rise with an additional influence above that
due to the opening area proper of the valve on which the steam acts when shut.
When the valve has risen the desired extent the cone (K) can be so forined as to
allow an increased escape of steam from chamber (H), and a correspondingly
diminished pressure in chamber (H) tending to open valve, and there to form an
equilibrium between the opening and closing tendencies of valve (A), which will
stand there until pressure in boiler is relieved, when valve (A) will return to its
seat.
The arrangement of cone (K) is not essential as a ferrule or grating can be
inserted in tube (C), or other convenient means used to throttle steam in
chamber (H) to desired extent; also the orifices (F, F,) can be varied in form,
so as to increase or diminish the escape of steam from face (B¹) proportionately to
rise of valve. The form of valve casing (G) can be varied to suit circumstances,
In the Drawing Figure 2 is a sectional elevation of the relief valve suitable for
fire engines or force pumps. This valve acts in a way similar to steam safety valve.
Similar parts in this valve are lettered same as corresponding parts in steam safety

page_text: valve. The valve casing (G) is in communication with delivery chamber or head
of pump.
The escape pipe I prefer to connect to suction chamber of pump, altho' it may
discharge into atmosphere; the face (B) of valve (A) discharges direct into escape
pipe the face (B¹) discharges into chamber (H), and then thro tube (C) to escape
pipe. The area of escape thro tube (C) may be regulated same as steam safety
valve; it is shown in Drawing to be throttled by a washer (O), but a grating or
other convenient means may be used.
In some cases the retardation of water in passing down tube (C) is sufficient to
create a pressure in chamber (H) to give an easy opening to valve (A).
The valve is shown to be loaded by carrying a spindle attached to valve (A)
thro' a stuffing box in chamber (H) to an external lever loaded by a spring balance,
altho weights or springs direct or with the intervention of levers may be used to
load the valve.
Instead of discharging thro tube (C) from face (B¹) to escape pipe I can form a
passage in casing (G) connecting chamber (H), and and escape pipe to discharge thro;
this area of discharge may be regulated. In this plan tube (C) would be closed or
used in combination with the said passage.
Having thus described the nature of my Invention, and the manner of performing
the same, I wish it to be understood that I claim,-
The arrangement and construction of safety valves having double faces, so con-
trived that when shut a part only of the valve has to be balanced by springs or
weights, and on the valve opening the escaping fluid will so act on the valve
as to assist the further opening of the same until the desired opening is reached.
Also the means for regulating the opening and closing of the valve, all constructed
in the manner and for the purpose illustrated and specified.
In witness whereof, I, the said James Cadoux Hudson, have hereunto set my
hand and seal, this Eighteenth day of April, One thousand eight hundred
and seventy-eight.
Witness,
HENRY WRIGHT.
JAMES CADOUX HUDSON. (L.S.)