An Improved Safety-valve.
Year: 1892

page_text: The decision of the Comptroller-General, of the 28th day of June 1893, allowed,
under Section 18 of the Patents, &c. Act, 1883, an Amendment of this
Specification.
Date of Application, 9th Feb., 1892
Complete Specification Left, 18th June, 1892-Accepted, 24th Sept., 1892
PROVISIONAL SPECIFICATION.
An Improved Safety-valve.
I, JOHN ROBERT NIXON of Great Usworth, Washington Station, in the County
of Durham, Engineer, do hereby declare the nature of this invention to be as
follows
amount.
--
The invention consists of an improved apparatus for relieving the pressure in
vessels containing liquids or fluids when that pressure exceeds a pre-determined
It belongs to that class of apparatus called safety valves or relief valves,
and it is especially applicable to steam generators or boilers. When applied to a
boiler it not only permits the surplus steam to escape when the pressure rises
above a certain degree, but, independently of the pressure, it discharges the steam
from the boiler when the level of the water falls below a pre-determined point.
In its simplest form the apparatus consists of one regulating valve, and one
discharge valve, arranged in and upon a valve casing, or valve stem: The regu-
lating valve determines the pressure at which relief is given, and the discharge
valve determines the amount of opening through which the surplus contents of the
vessel escapes. These valves are so connected, that the regulating valve must act
before the discharge valve can act, but also, so that the discharge valve must act
immediately after, or almost simultaneously with, the regulating valve. For boilers
a low water apparatus may be added, consisting of the usual arrangement of float,
lever, and counterpoise, I may use two or more regulating valves, and two or more
discharge valves in combination, and the valves may be of any form which will
enable them to perform the functions required of them.
I will now more particularly describe the form in which I prefer to construct my
apparatus when used as a safety valve upon a boiler.
At, or near, the top of a valve casing, or valve stem, the interior of which is in
communication with the interior of the boiler to which it is applied, I construct a
circular valve seat, the, orifice of which is opened or closed by a spherical valve
which is free to rise and fall. This is the regulating valve.
Projecting upwards from, and constructed with, or rigidly connected to, the
regulating valve, is a spindle which is enclosed in a tube or cylinder in which it
is free to rise and fall. Openings are made in the side of the tube which are
uncovered by the spindle when the regulating valve is raised from its seat.
Projecting downwards from, and constructed with, or rigidly connected to, the
regulating valve, is another spindle which is terminated at its bottom end by a
collar.
The regulating valve is pressed downwards by a spring or weight acting either
directly upon it, or through the medium of a lever.
Within the valve casing, and immediately below the regulating valve, I construct
an annular face, in which ports or openings are formed, through which communi-
cation can be made between the interior of the valve casing and the atmosphere.
The ports are opened and closed by a disc which is free to rise and fall. This is
the discharge valve.

page_text: The bottom spindle of the regulating valve passes through a central hole in the
disc. The hole is larger than the spindle but smaller than the collar on the bottom
of the spindle.
All
When the pressure in the boiler is at, or under, the pressure to which the
regulating valve is weighted both valves rest upon their respective seats.
openings between the interior of the valve casing and the atmosphere are then
closed. The disc then divides the valve casing into an upper and a lower chamber.
In this position of the valves the collar upon the bottom of the regulating valve
spindle is clear of the under surface of the disc, and the steam is free to pass from
the boiler into the upper chamber of the valve casing, and exert its full pressure
upon the regulating valve.
When the pressure rises beyond the point to which the regulating valve is
weighted, the regulating valve is raised from its seat, and at the same time the
collar upon the bottom of its spindle is brought up against the under surface of
the disc. Then the channel of communication between the upper and lower
chambers is closed. The steam escapes, past the regulating, from the upper
chamber, and thus reduces the pressure upon the upper surface of the disc, while
the under surface is still subject to the full boiler pressure, which raises the disc
from the annular face, and the surplus steam escapes through the openings
therein.
When the pressure falls again the two valves resume their normal position.
Inside the valve casing and immediately below the disc I place a ring which is
free to move up or down. The ring is connected, by two rods which pass down-
wards from it, to the lever of the low water apparatus. When the water falls
below a pre-determined point, the ring is forced up against the disc which is thus..
raised from its face, and the steam continues to escape through the ports thus
uncovered as long as the water remains too low.
Dated this 9th day February 1805
4
An Improved Safety-valve.
I, JOHN ROBERT NIXON, of Great Usworth, Washington Station in the County
of Durham, 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 consists of an improved apparatus for relieving the pressure in
vessels containing liquids or fluids, when such pressure begins to rise above a pre-
determined working one. It belongs to that class of apparatus called safety-valves,
and is especially applicable to steam boilers. When applied to a steam boiler it
can be arranged to act in the combined capacities of an escape-valve when the
pressure begins to rise above the working pressure, and, independently of the
pressure, as an escape-valve for the steam when the water falls below a pre-determined
level.
In the following statement I shall only describe my invention as it is constructed
when used as a safety valve on a steam boiler, but it will be seen that it may be
used for any purpose to which a relief valve is applicable.
The object of my invention is to improve the construction of safety-valves in which
the loads upon the valves, while being dependent upon the working pressure, are
independent of the areas of the outlets through which the surplus steam is discharged.
so that safety-valves-constructed-according to my invention may be equally-loaded
for the same working pressure, while the areas of the outlets may be varied to any
extent within practicable limits.
The principle of the safety apparatus to which my invention applies consists in the

page_text: employment of a valve, or a set of valves, which may be termed outlet valves,
whose purpose is to open and close the outlets at the proper moments; and which
act in combination with another valve, or another set of valves, which may be
termed pressure valves and whose purpose is to determine the moments when the
cutlet valves shall act.
In some cases it may be necessary to add weights to the outlet valves to make
them close against a frictional resistance, but in most cases they will close by their
own weights, or by the pressure of steam upon them and in no case are they "loaded"
in the technical sense of that term, because the pressure of the steam has no
tendency to move them under the ordinary working conditions of the boiler, but on
the contrary, has a constant tendency to keep them closed against the outlets, I
will therefore describe them as "unloaded valves."
The pressure valves are acted upon by the pressure of the steam in the boiler,
and are loaded to resist that pressure up to a certain amount as in ordinary safety-
valves, consequently they will be described as "loaded valves."
My invention may be carried into effect in a number of different ways such as
hereinafter-shown and described; but I would-have-it-understood that I do not
confine-myself-to-the-particular arrangements, or to the special forms of valves
shown-and-described, but-reserve-to-myself-full-liberty-of-using-any-arrangement
that I may find convenient, so-long as it contains the principle-and accomplishes
the object of my invention, and any forms-of-valves-so-long as they serve the purpose
and perform the functions herein-specified.
My invention consists in improved pressure and outlet valves, and in the arrangement
of low water apparatus, all as hereinafter set forth.
In the drawings the pressure valves are all shown loaded by direct acting
weights, but the loads may consist either of weights or springs, and either may act
direct upon the valves or through the medium of levers.
DESCRIPTION OF DRAWINGS.
Fig. 1, is an elevation in section of my improved apparatus or safety valve.
Figs. 14, and 1B, are detail views (as hereinafter explained).
Fig. 2, is an elevation in section of a modification of my improved apparatus
or' safety-valve.
Fig. 3, is an elevation of another modification of my improved apparatus or
safety-valve.
Fig. 4, is a sectional view of modification of my improved apparatus.
Fig. 5, is a detail view, as hereinafter explained.
Fig. 1, and the detail views thereof :-A is the base of a valve casing, the interior
of which is in communication with the interior of the boiler, to which the apparatus
is applied, B is a cover securely bolted to the base and having snugs B' upon the
bottom of it, by means of which the cover B is kept central with the base A and
the rise of the outlet valve is limited.
Near the top of the base a face C is formed in which is cut or formed an
annular opening C, through which the surplus steam escapes. The outlet is closed
by the outlet valve D, which is a disc with a tubular centre. E is a bush fixed
in the cover B, and provided with holes F. The upper orifice of the bush is
shown closed by the pressure valve G. That portion of the pressure valve which
occupies the greater portion of the bush is made with wings G¹ which are shown
in section at Fig. 1. The lower portion of the pressure valve is tubular in form.
Immediately below the bush E the tubular part of the pressure valve G is
provided with holes H. The upper end of the tubular portion closes the lower
orifice of the bush while the lower end passes through the central hole of (and
acts as a guide for) the outlet valve D. A channel of cominunication is thus
formed between the boiler and the space X above the outlet valve D through
the tubular portion of the pressure valve and the holes H. I is the weight carrier.
J, J, are weights. K is a spindle resting upon the pressure valve, and upon which
the weight carrier is supported. L is a tube screwed into the cover B. M is a

page_text: -
guide for the spindle K, screwed into the top of the tube L. N are holes through
which the steam from the pressure valve escapes into the atmosphere. T is the
lever of the low water apparatus, U the fulcrum, O a rod which is free to rise and
fall with the lever, and which is kept central with the base by the arms Q, which
are shown in plan at Fig. 1B. The remainder of the low water apparatus is of the
usual construction and is therefore not illustrated. R is the boiler plate, S a ring
riveted to the boiler to which the base A is bolted.
The action is as follows:-
When the pressure of the steam in the boiler to which one of my improved safety
valves is applied under or about the working pressure, both the pressure and
outlet valves remain in the position shown in the drawing. All the openings
between the atmosphere and the interior of the valve casing are closed, but
the steam is free to pass from the boiler to the space X through the tubular
portion of the pressure valve and the holes H. All the exposed surfaces of the
outlet valve are then subject to the boiler pressure and the valve has no tendency
to move while these conditions are maintained.
When the pressure of the stean in the boiler begins to rise above the working
pressure, the pressure valve is forced upwards and the holes H go up inside the
bush E, which partially closes the channel of communication between the boiler and
the space X. But by the same movement the lip of the pressure valve is raised from
its seat, which opens a channel of communication between space X and the atmo-
sphere through holes F. Then the steam, except a small amount of leakage, ceases
to flow from the boiler into the space X, but the steam in that space is free to
escape into the atmosphere, which reduces the pressure upon the top of the outlet
valve to nearly atmospheric pressure, while the exposed under surface of the valve
is still subject to full boiler pressure; the excess of upward pressure then raises..
-the outlet valve and the surplus steam escapes through the outlets.
When the pressure of the steam begins to again fall below the working pressure,
the pressure valve descends, and closes the channel between the atmosphere and
space X and at the same time opens the channel between space X and the boiler.
The steam from the boiler then rushes up the tube of the pressure valve, through
the holes H and fills the space X. The outlet valve is then in equilibrium and
falls by its own weight, and thus closes the outlets.
Fig. 2. In this modification the outlets are a number of holes (arranged in a circle
and shown closed by the cylindrical outlet valves D, which are free to rise and fall
in the bushes D', fixed in the upper part of the base A. This figure shows another
form of pressure valve G. The bush E is carried down through the top part B
of the base A and the part of the pressure valve which occupies the bush is a spindle
with guide wings G' formed on it near the top and bottom. A collar of the same
diameter as the bore of the bush forms the bottom of the pressure valve, and is
shown a little below the bottom of the bush leaving an opening H for the passage
of the steam from the boiler to space X through holes F. The action of this
modification is as follows: When the pressure of the steam in the boiler is under
or about the working pressure both the pressure valve G and outlet valves D
remain in the position shown in the drawing. All the openings between the atmo-
sphere and the interior of the valve casing are closed, but the steam is free to pass
from the boiler to the space X through the opening H and holes F. All the
exposed surfaces of the outlet valves are then subject to the boiler pressure and
while these conditions are maintained the valves have no tendency to move.
When the pressure of the steam in the boiler begins to rise above the working
pressure the pressure valve G is forced upward inside the bush E, and the
opening H is closed, which closes the communication between the boiler and the
space X. But by the same movement the top of the pressure valve G is raised
from its seating which opens a channel of communication between space X and
the atmosphere through holes N, so allowing the steam in the space X to escape
into the atmosphere which reduces the pressure upon the top of the outlet valves D
to about atmospheric pressure while the exposed under surfaces of the valves are

page_text: still subject to full boiler pressure; the excess of upward pressure then raises the
outlet valves, and the surplus steam escapes through the outlets C.
When the pressure of the steam begins to again fall below the working pressure
the pressure valve G descends and closes the channel of communication between
the atmosphere and space X and at the same time opens the channel between
space X and the boiler. The steam from the boiler then rushes up through the
opening H and holes F, and fills the space X. The outlet valves D then descend
and again close the outlets C.
Fig. 3. In this modification the outlets are holes or ports C formed in the side of the
valve stem or base A, and the outlet valve is in the form of a piston D. A packing
ring is placed in a recess formed in the piston and is pressed against the outlets
by the steam which gets to its inner surface through the channels D. A weight R
is fixed to the bottom of the spindle O, to overcome the friction which would other-
wise prevent the valve from closing. S is a perforated disc which prevents the
outlet valve coming down too far, and is shown in plan at Fig. 5.
Fig. 4. The outlet valve D is shown with the upper surface enlarged so that the
pressure of the steam upon the top of the valve may close it at the proper moment
without the assistance of added weight. The pressure valve G is a spindle enlarged
at the top and bottom, and is without guide wings inside the bush, but the spindle K
is guided at the bottom by the collar K', as well as at the top.
The action of these modification is as follows: The channel of communication
between the boiler and the space X is closed when the pressure valve is raised
by the collar on the bottom of the valve going up inside the bush, and communi-
cation is made between the boiler and the space X through the holes H¹ and H.
The action of these modifications will be easily understood without further explana-
tion, after the description given with reference to Figs. 1, and 2.
The action of the low water apparatus may be shortly described.
First as to Fig. 1 When the water falls below the low water mark, the lever T
turns upon the fulcrum U and raises the rod O, which lifts the pressure valve G,
and so allows the steam to escape from space X, and closes the holes H, so that
the pressure of the steam beneath the outlet valve D raises that valve and allows
the steam to escape so long as the water remains too low.
The arrangement shown in Fig. 3, acts in a similar manner. The projection (¹
upon the lever T comes up against the collar T' and as the water falls the outlet
valve D is raised until the outlets are open.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I could have it understood
that I lay no general claim to the employment of unloaded outlet valves acting in con-
junction with loaded pressure valves in the construction of safety apparatus for steam
boilers, but I declare that what I do claim is :-
1. In safety apparatus for steam boilers and other analogous purposes the
combination of one or more unloaded valves acting in conjunction with one.
or more loaded valves (the latter of which open inwardly, and move, when closing in
the same direction as the escaping steam), as and for the purposes substantially as
described and illustrated.
2. In connection with safety-valves for steam boilers having one or more
unloaded valves acting in conjunction with one or more loaded valves the employ-
ment of the low water apparatus operating substantially as herein-before shown
and described.
JOHN E. WALSH,
Royal Exchange Chambers, Boar Lane, Leeds,
Patent Agent for the Applicant.