Improvements in Safety Valves.
Year: 1892

page_text: Date of Application, 29th Oct., 1892
Complete Specification Left, 19th July, 1893-Accepted, 19th Aug., 1893
PROVISIONAL SPECIFICATION.
Improvements in Safety Valves.
We, THOMAS BUDWORTH SHARP, of French Walls, Smethwick, in the County
of Stafford Mechanical Engineer, and JAMES ASHTON FLETCHER and SAMUEL
FLETCHER, both of Borough Brass Works, Ashton-under-Lyne, in the County of
Lancaster, Brassfounders do hereby declare the nature of this invention to be as
follows:-
Our invention consists of the construction and combinations of parts hereinafter
described of safety valves, particularly applicable to steam boilers, whereby the
Baid valves are made very efficient in action and a large clearance is provided for
the blowing off of steam."
Our invention consists principally in the combination of an unloaded valve of
large diameter with a small subsidiary loaded valve the said large unloaded valve
being pressed to its seat, when not blowing off steam, by the boiler pressure so
that a perfect joint of the valve on its seat is obtained.
We will describe our improved safety valves as used with steam boilers.
We make the valve box or case with an expanded head or flat chamber, the
internal diameter of which is about the same as that of the large principal valve
which we use. This expanded head or chamber is closed by a disc or cover having
a small axial tubular passage the top of which forms a seat for the small subsidiary
loaded valve. The bottom of the flat chamber of the valve box or case constitutes
the seat of the large principal valve and the said flat chamber is filled slowly with
steam of the boiler pressure by means of a small hole or holes near the middle of
the large principal valve. In the bottom or valve seat of the steam chamber
described an annular recess is made thereby leaving two concentric annular pro-
jections for the large valve to seat itself upon. By means of holes or perforations
in the bottom of the steam chamber opening into the said annular recess the latter
is put into communication with the external air. Through these holes and per-
forations and annular recess the steam blows off or escapes when the large principal
valve is raised from its seat, the lifting of the said large valve in its chamber
being limited by stops on the underside of the disc or cover closing the said
chamber.
By the arrangement described steam of boiler pressure presses on portion of
the underside of the large valve and passing by the small holes in the said valve
fills the chamber above it and presses upon the whole of the upper side of the said
valve. In consequence of the effective area of the upperside of the said valve being
considerably in excess of that of its underside it is pressed down to its seat by the
boiler pressure and a perfect joint obtained. Thus no dead weight need be used on
the larger valve which may be pressed to and maintained on its seat by boiler
pressure only although in some cases the said larger valve may be partially
weighted. The underside of the small subsidiary loaded valve at the top of the
valve case is pressed upon by steam of the boiler pressure in the small steam
chamber above the large valve and the said small subsidiary valve is so loaded as
only to be lifted from its seat when the boiler pressure exceeds that at which the
boiler is arranged to work.
On the small loaded valve being lifted from its seat the steam pressure in the
chamber under it being immediately reduced below that of the boiler pressure
the large valve is lifted from its seat and opening the annular recess and holes or
perforations in the bottom of the steam chamber the steam rapidly blows off by
the said recess and holes.

page_text: The parts of the safety valve may be modified in the following manner. Fixed
at the bottom of the small steam chamber in the valve case is a plate or disc
perforated near its margin. This plate carries on its upperside à collar or sleeve
projecting into the steam chamber. In this collar or sleeve a large inverted cup
shaped valve works loosely so as to form a clearance or passage between the said
valve and the collar or sleeve. Steam of the boiler pressure passes by the per-
forations near the margin of the fixed plate into the chamber above it and thence
by the clearance or passage between the collar or sleeve and inverted valve into
the interior of the said valve. By the steam pressure within the inverted cup
shaped valve it is lifted to and maintained against its seat at the top of the steam
chamber and adjoining a large blow off pipe. Above and carried by the cup
shaped steam supported valve and situated in the blow off pipe is a small loaded
valve which seats itself on a seat in the top of the cup shaped valve. The small
loaded valve last described has the same function as the loaded valve in the first
described arrangement; namely to relieve the pressure on the large cup shaped
valve when the pressure within the boiler exceeds that at which the boiler is
arranged to work.
On the small loaded valve being lifted from its seat the pressure within the cup
shaped valve is reduced and it descends from its seat sliding in its collar or sleeve
on the fixed bottom plate of the steam chamber. The chamber containing the cup
shaped valve being thus open to the external air steam rapidly blows off at the
open top of the said chamber into the large blow off pipe at the top of the valve
case.
In safety valves made according to our invention the large valve may be made
of much less area than an ordinary safety valve as the lift is greater.
Dated this 29th day of October 1892.
W. T. WHITEMAN,
Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Safety Valves.
We THOMAS BUDWORTH SHARP of French Walls Smethwick in the County
of Stafford Mechanical Engineer. and JAMES ASHTON FLETCHER and SAMUEL
FLETCHER both of Borough Brass Works, Ashton-under-Lyne in the County of
Lancaster, Brass founders do hereby declare the nature of the said invention and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement:-
Our invention consists of the construction and combinations of parts hereinafter
described of safety valves particularly applicable to steain boilers, whereby the said
valves are made very efficient in action and a large clearance is provided for the
blowing off of steam.
Our invention consists principally in the combination of an unloaded valve of
large diameter with a small subsidiary loaded valve, the said large unloaded valve.
being pressed to its seat when not blowing off steam by the boiler pressure so that
a perfect joint of the valve on its seat is obtained.
We will describe our improved safety valves as used with steam boilers.
We make the valve box or case with an expanded head or flat chamber, the
internal diameter of which is about the same as that of the large principal valve
which we use. This expanded head or chamber is closed by a disc or cover having
a small axial tubular passage in which the small subsidiary loaded valve is seated.
The bottom of the flat chamber of the valve box or case constitutes the seat of the
large principal valve and the said flat chamber is filled with steam of the boiler.
pressure by means of an axial hole in the stalk of the large principal valve. In the
bottom or valve seat of the steam chamber described an annular recess is made
thereby leaving two concentric annular projections for the large valve to seat itself

page_text: upon. By means of holes or perforations in the sides of the steam chamber
opening into an annular recess, the latter is put into communication with the external
air. Through these holes or perforations and annular recess the steam blows off or
escapes when the large principal valve is raised from its seats the lifting of the said
large valve in its chamber being limited by an annular projection which constitutes
the seat of the lifted valve.
By the arrangement described steam of boiler pressure presses on a portion of
the underside of the large valve and passing by the axial hole in the stalk of the
valve fills the chamber above it and presses upon the whole of the upperside of the
said valve. In consequence of the effective area of the upperside of the said valve
being in excess of that of its underside it is pressed down to its seat by the boiler
pressure and a perfect joint obtained. Thus no dead weight need be used on the
larger valve which may be pressed to and maintained on its seat by boiler pressure
only, although in some cases the said larger valve may be sufficiently weighted to
ensure precision of action.
The underside of the small subsidiary loaded valve at the top of the valve case is
pressed upon by steam of the boiler pressure in the steam chamber above the large
valve and the said small subsidiary valve is so loaded as only to be lifted from
its seat when the boiler pressure exceeds that at which the boiler is arranged
to work.
On the small loaded valve being lifted from its seat the steam pressure in the
chamber under it being immediately reduced below that of the boiler pressure the
large valve is lifted from its seat and opening the annular recess and holes or
perforations in the sides of the steam chamber, the steam rapidly blows off by the
said recess and holes.
In safety valves made according to our invention the large valve may be made of
much less area than an ordinary safety valve as the lift is greater.
We will now proceed to describe with reference to the accompanying drawing the
manner in which our invention is to be performed.
Figure 1 represents in vertical section a safety valve for a steam boiler the parts
of the said safety valve being constructed according to our invention;
Figure 2 represents in elevation the valve box or case and Figure 3 represents a
half plan of the same.
.
The same letters of reference indicate the same parts in Figures 1, 2 and 3.
a. is the valve box or case provided at top with a flat chamber b. in which the
large principal valve c. works the said valve c. seating itself on the annular seats d.
and at the bottom of the chamber b. The top of the chamber b. is closed by the
disc or cover e. having in it an axial passage 62 opening into the said chamber b.
In the passage the small loaded subsidiary valve f. is seated as represented.
The stalk of the large principal valve c. has an axial hole and through the
hollow stalk c steam of the boiler pressure passes into and fills the chamber b. and
presses on the top of the valve; steam of the boiler pressure also presses on the
underside of the valve c. In the seat of the large valve c. a deep annular recess h.
is made thereby leaving the two concentric projections d. and di for the said large
valve c. to seat itself upon. In the sides of the valve box or case a. is a series of
holes or perforations g. (see Figure 2) opening into the annular recess h. By
means of the said holes g. and annular recess h. the chamber b. is put into communi-
cation with the external air and through the said holes and recess the steam blows
off or escapes when the principal valve c. is raised from its seat. The lifting of the
principal valve c. in the chamber b. is limited by the annular projection i. on the
top of the said valve seating itself against the underside of the valve box cover e.
The position of the limiting annular projection or seat i. of the lifted valve with
respect to the annular projection d. on the valve sent is seen in Figure 1.
Steam of boiler pressure presses on a portion of the large valve c. and passing by
the axial hole in the stalk of the said valve fills the chamber b. and presses upon
the whole of the upper side of the said valve c. As the effective area of the upper
side of the principal valve c. is in excess of that of its underside the said valve is
.

page_text: pressed to its seat by the boiler pressure. To ensure however the fall of the
valve or its precision of action it may be made of sufficient weight to effect that
object.
The underside of the small subsidiary loaded valve f. at the top of the valve case
is pressed upon by the steam of boiler pressure in the chamber b. and the said small
subsidiary valve f. is so loaded as only to be lifted from its seat when the boiler
pressure exceeds that at which the boiler is arranged to work. In the drawing we
have shown the loaded valve f. pressed to its seat with the required pressure by a
coiled spring, but it may be pressed to its seat by weights.
From the foregoing description and by an examination of the drawing it will be
understood that on the small loaded valve f. being lifted from its seat the steam
pressure in the chamber b. is immediately reduced below that of the boiler
pressure and the large principal 'valve c. is lifted from its seat, and the steam
pressure immediately cut off from the upper side of the valve by the seating of its
annular projection i. on the underside of the cover e. By the lifting of the valve c.,
the annular recess h. and holes or perforations g.. in the sides of the valve box a. are
opened to the external air and the steam rapidly blows off by the said recess h. and
holes g.
.
Having now particularly described and ascertained the nature of our invention
and the manner in which the same is to be performed we declare that we claim
as our invention of." Improvements in safety valves ";
-
The combination with a large principal valve of the kind described and repre-
sented working in a steam chamber in the valve box and open to the boiler pressure,
of a small subsidiary loaded valve pressed upon by the boiler pressure in the said
small chamber, both sides of the said large principal valve being pressed upon by
steam of the boiler pressure, the effective area of the upper side of the said large
valve being in excess of that of its underside so that the said valve is pressed to and
maintained on its seat by the boiler pressure, the lifting of the loaded valve reducing
the pressure on the upper side of the large valve and causing the said large valve
to be lifted from its seat for the blowing off of the steam, the several parts of the
safety valve being arranged or combined and acting substantially as herein before
described and illustrated in the accompanying drawing.
Dad the teal JC T... 100
THOMAS BUDWORTH SHARP.
JAMES ASHTON FLETCHER.
SAMUEL FLETCHER.