IMPROVEMENTS IN SAFETY VALVES
Year: 1879

page_text: LETTERS PATENT to Hamilton Weldon Pendred, Civil Engineer, of Ford Point,
Lower Broughton, Salford, Lancashire, for the Invention of "IMPROVEMENTS
IN SAFETY VALVES."
Sealed the 4th June 1880, and dated the 5th December 1879.
PROVISIONAL SPECIFICATION left by the said Hamilton Weldon Pendred
at the Office of the Commissioners of Patents on the 5th December 1879.
HAMILTON WELDON PENDRED, Civil Engineer, of Ford Point, Lower Broughton,
Salford, Lancashire. "IMPROVEMENTS IN SAFETY VALVES."
In carrying out this Invention I make the safety valve in several parts, that is
to say, each complete valve consists of two or more seats and valves, each seat
having a valve appertaining to it, but the seat of one valve is also the valve
appertaining to the seat next below. Between the seperate movable parts I
interpose springs, which may be coiled springs of hard brass or steel, but other
materials or other forms may be employed, which springs operate to separate the
several parts of the valve, that is to say, to lift the valves from their respective seats
when the pressure, which the safety valve is intended to keep within certain limits,
shall be sufficient to overcome a load or weight holding the several parts of the
valve in contact. A spring or springs of the well known helical type may be used
instead of separate valves and seats, such a spring when compressed so that the coils
are in contact, constituting a tube of which the top is stopped by a plate, while the
bottom is open to the boiler or other vessel containing a fluid or liquid under
pressure. The coiled spring may be loaded in any suitable way, as by a lever and
weight. When the pressure exceeds the proper limit the tube becomes lengthened,
and the steam, air, water, &c., escapes between the coils which are no longer in
contact. In certain cases the valve may be made of two or more elastic rings, each
ring cut through diagonaly in one place, said rings being so made that the upper or
under surface of each shall lie in one plane until the load is overcome by the
pressure, when each ring will, by virtue of its elasticity, rise at soine part of its
circumference from the ring next below, and permit the escape of the fluid whose
pressure is to be prevented from augmenting.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Hamilton Weldon Pendred in the Great Seal Patent Office on the
5th June 1880.
HAMILTON WELDON PENDRED, Civil Engineer, of Ford Point, Lower Broughton,
Salford, Lancashire. "IMPROVEMENTS IN SAFETY VALVES."
In carrying out this Invention I make the safety valve in several parts, as shown
in Figure 1 of the annexed Sheet of Drawings, that is to say, each complete valve
consists of two or more seats and valves a, a, a, a, each seat having a valve
appertaining to it, but the seat of one valve is also the valve appertaining to the
seat next below, as clearly shown.
Between the separate movable parts a, a, a, a, I interpose springs b, b, b, (which
may be coiled springs of hard brass or steel, but other materials or other forms may
be employed) which springs operate to separate the several parts of the valve, that
is to say, to lift the valves from their respective seats when the pressure which the
safety valve is intended to keep within certain limits shall be sufficient to overcomo
a load or weight holding the several parts of the valve in contact.
As shown in Figure Ĭ the several parts of the valvo are held in proper position
one over the other by means of the casing c, which is provided in its interior with
vertical ribs d for that purpose.
The lond on the valve is obtained by the springs c, c, and lever fin the manner
well known, or it may be by a weight suspended from the top portion of the valve,.
or the usual lever and weight may be employed.
The casing is provided with openings g, g, for the escaping steam, which can
also find an outlet at the top of the casing.
As a modification a spring or springs of the well known helical type may be used
instead of separate valves and seats, such a spring, when compressed so that the
coils are in contact, constituting a tube of which the top is stopped by a plate,
while the bottom is open to the boiler or other vessel containing a fluid or liquid
under pressure.
In Figure 2 I have shown such a modification; the tube forming the valve is
composed of two helical springs a, a', folded on each other, the joints between the
folds or layers of the coils being properly ground and made steam or liquid
tight.
The tube rests upon a seating h, and the interior of it is in communication with
the boiler or other vessel to which it may be fitted.
The top of the tube is closed by the cap piece i, and the load on it is carried by
the rod the latter being provided with a spherical top end k resting in a seating
in the bottom of the socket formed on the cap piece i.
The whole is enclosed in a casing c so that it cannot be tampered with, and the
casing is provided with openings g, g, to allow free escape for the issuing steam or
fluid as the case may be.
The coiled spring, though loaded as shown in Figure 2, may be loaded in any
suitable way, as by a lever and weight, or as in Figure 1.
When the pressure exceeds the proper limit the tube becomes lengthened and the
steam, air, or water escapes between the coils which are no longer in contact.
In certain cases the valve may be made of two or more elastic rings a, a, as
shown in Figure 3, each ring cut through diagonally in one place, said rings being
so made that the upper or under surface of each shall lie in one plane until the
load is overcome by the pressure, when each ring will, by virtue of its elasticity,
rise at some part of its circumference from the ring next below, as shown in
Figure 4, and permit the escape of the fluid whose pressure is to be prevented from
augmenting.

page_text: And having now described the nature of my said Invention, and in what
manner the same is to be performed, I declare that I claim,-
The improvements in safety valves as hereinbefore described, and substantially as
shown in the annexed Drawings.
In witness whereof, I, the said Hamilton Weldon Pendred, have hereunto set
my hand and seal, this Second day of June, One thousand eight hundred
and eighty.
HAMILTON WELDON PENDRED. (L.S.)