IMPROVEMENTS IN SAFETY VALVES
Year: 1877

page_text: LETTERS PATENT to Thomas Messenger, of River, near Dover, in the County
of Kent, Civil Engineer, for the Invention of "IMPROVEMENTS IN SAFETY
VALVES."
Sealed the 23rd November 1877, and dated the 4th June 1877.
PROVISIONAL SPECIFICATION left by the said Thomas Messenger at the
Office of the Commissioners of Patents on the 4th June 1877.
THOMAS MESSENGER, of River, near Dover, in the County of Kent, Civil
Engineer. "IMPROVEMENTS IN SAFETY VALVES."
My Invention relates to improvements in spring safety valves, with the object of
preventing undue accumulation of pressure in the boiler, when the valve lifts above
tbut pressure at which it has been set to blow off, and in the event of the spring
breaking to enable the valve to be weighted in the ordinary manner while a
new spring is being fixed, during which time the means used to overcome the
accumulative resistance of the spring when the valve lifts will be neutralized.
My improvements also comprise a method of more conveniently attaching the
spring to operate on ordinary safety valves, and I provide a steam chest to which
the valves and any other boiler mountings may be fixed, and having a single pipe
leading from the boiler.
The accompanying Sheet of Drawing illustrates a safety valve of my Invention,
Figure 1 being a sectional elevation, and Figure 2 a sectional plan of same through
the line q, T.
The valve box is divided into two compartments a and b; the valve, which may
be called an equilibrium valve, is made as usual at its lower part c, and is continued
upward, its upper part d forming a piston working loosely in the circular opening e,
this opening forming a communication between the two compartments a and b of
the valve box. The compartment o has a nozzle f opening outward, and the com-
partment b has a tapered exit g which leads to the waste steam pipe; h is a hollow
screwed spindle made of a larger diameter where it passes through the valve box
cover i; jis the valve spindle, having a collar k at its upper end, passing loosely
through the hollow spindle and bearing on the valve; is a spiral spring attached
Price GIT

page_text: at its extremities to two washers m, m²; these washers have a circular groove in
which the spring beds truly for rather more than half a turn, and is held in these
grooves by means of eye bolts as shown. The upper washer m is loose on the valve
spindle and bears on the collar k, the lower washer m¹ is attached to the hollow
screwed spindle has a nut; n is a forked weighted lever, which when attached to
the fulcrum o bears on the upper face p at the lower part of the hollow spindle h.
Manner of Operating. The spiral spring is attached to the two washers m
and m³, and placed over the spindle j, the washer m resting loosely on the collar k,
and the washer m¹ being screwed downward on the hollow spindle h, which it lifts
upward, pressing it against the steam-tight face inside the valve box cover; this
washer m³ is then further screwed downward until the spring attains a sufficient
tension to give the required downward pressure on the valve spindle collar k. Thus
-when-the-steam-blows_off_from_the_boiler_past_the_lower part of the valve at c,
and passes out of the compartment a of the valve box through the nozzle f, a
partial vacuum is caused in the outer compartment b by means of the tapered exit g
which leads to the waste steam pipe on the principle of the ordinary injector,
and this partial vacuum, operating on the upper part of the valve d, assists the
valve to rise, and so counterbalances the undue accumulative resistance of the spring
as the valve lifts.
In the event of the spring breaking it would immediately separate at the broken
part, and the spring pressure being thereby released from the valve spindle, the
valve would immediately fly upward its full lift, and come in contact with the
bottom part of the hollow spindle at p¹; then the forked weighted lever n being
fixed in its place and pressing on the face 2 would by means of this hollow spindle
pressing downward on the top of the valve, take charge of the valve until a new
spring could be fixed, and at this time the weighted lever not causing any accumu-
lation of pressure as it rises, the means adopted to overcome this accumulation when
the spring is at work is neutralized by means of the larger part of the hollow spindle h,
where it passes through the valve box cover, its sectional area here providing a
surface on which the vacuum acts downward, which area, being properly pro-
portioned, places. the valve at this time in equilibrium so far as the vacuum is
concerned.
For ordinary safety valves, such as are used in locomotives and other boilers, the
same method of attaching the spring may be used, two valves arranged side by side
with a lever overhead pressing on them, the spring being between the valves.
The lever is formed with a groove in it corresponding with the top washer and
the lower washer screwed on to a central spindle, which spindle being revolved
will screw this washer downward, and so put the desired tension on the spring to
operate on the valves; this arrangement may be used with or without the vacuum
chamber, as required.
A single steam pipe may lead out of the boiler in this arrangement, communicating
with a steam chest on which the valves are fixed; this steam chest will be very
convenient for attaching the usual boiler mountings to.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Messenger in the Great Seal Patent Office on the 30th
November 1877.
THOMAS MESSENGER, of River, near Dover, in the County of Kent, Civil
Engineer. "IMPROVEMENTS IN SAFETY VALVES."
The object of these improvements in safety valves is to prevent undue accumu-
ation of pressure when the valve begins to lift above that pressure at which
the valve may be set to commence to blow off, and in other parts connected
therewith.
The annexed Drawings will describe the manner in which I intend practically to
carry out these improvements.
Figure 1 is a sectional elevation, and Figure 2 is a sectional plan through q, r, of
one method to prevent undue accumulation of pressure.
Figure 3 is a sectional elevation through g', ; Figure 4 is a sectional elevation
through g², and Figure 5 is a plan shewing a method of attaching springs to a
lever between two valves.
Figures 1 and 2 refer to one method in which I propose to prevent undue accumu-
lation of pressure.
The valve box is divided into two compartments a and b; the valve proper is
shown at c, and is continued upwards and enlarged as shewn at d, or otherwise
enlarged at the point of communication e between the compartments a and b of the
valve box. The compartment a has a nozzle opening outwards, and the compart
ment b has a tapered exit g which leads to the waste.steam pipe.
When a weighted lever is used to take charge of the valve in the event of the
'spring breaking, and the spring used is in tension, h is a hollow screwed 'spindle
passing through the valve box cover i; j is the valve spindle having a collar k at its
upper end, and passing loosely through the hollow screwed spindle h, and bearing
on the valve; is a spiral spring attached at its two extremities to two washers m
and m'; these washers have a circular groove in which the spring beds truly for
rather moro then half a turn, the spring being held in these grooves by means of
the eye bolts shown; the upper washer m is loose on the valve spindle and bears on
the collar k; the lower washer m¹ is attached to the hollow screwed spindle has a
nut; n is a forked weighted lever (shown in dotted lines,. Figure 1), which when
attached to the fulcrum o bears on the face p at the lower part of the hollow
spindle h.
Modus Operandi.-The spiral spring being attached to the two washers m
and m is placed over the spindle j, the washer m resting loosely on the collar k,
and the washer m² being screwed downwards on the hollow spindle lifts it upwards,
pressing it against the steam-tight face inside the valve box cover, this washer mi
then being further screwed downwards until the spring attains a sufficient tension
to give the desired downward pressure on the valve spindle collar k. Then when
the steam blows off from the boiler past the lower part of the valve at c, and passes
out of the compartment a of the valve box through the nozzle f, a difference of
pressure is caused in the outer compartment b by means of the tapered exit g which
leads to the waste steam pipe, on the principle of the ordinary injector, and this
difference of pressure operating on the upper part of the valve at d assists it to rise,
and so prevents undue accumulation of pressure.
In the event of the spring breaking it would immediately separate at the broken
part, and the spring pressure being thereby released from the valve spindle, the
valve would immediately fly upwards its full lift, and como in contact with the
bottom part of the hollow screwed spindle at p, then the forked weighted lever n
(shown in dotted lines, Fig. 1) being fixed in its place, and pressing on the face P
would by means of this hollow spindle prossing downwards on the top of the valve
take charge of it until a new spring could be fixed, and the lifting power of
the valve, which comes into operation against the accumulative power of the

page_text: spring may be counterbalanced by bending the lever n, so that it increases in leverage
as it rises.
When the precaution of the weighted lever is not required, the separate hollow
moveable screwed spindle will not be wanted, but may be made in one with the
valve box cover. Of course I may also apply springs in compression to act on
this valve in the usual manner without the weighted lever, or with this lever
suitably adapted.
For ordinary safety valves such as are used on locomotives and other boilers, I
intend to use the same manner of attaching the spring when in tension; one way-of
carrying this out is shewn in Figures 3, 4, and 5.
Two valves c', c, are arranged side by side, having a lever n² overhead, pressing
on them (this lever may be continued as shewn in dotted lines to ease the valves
according to Mr. Ramsbottom's plan), the upper washer being attached to this lover,
or the lever may be made larger here, as shown, and the groove formed in it, the
lower washer being adjusted downwards on the spindle ¹ by means of the long
ferrule and the nut m³, so as to give the desirod pressure on the valves. The
chamber a¹ may be made of any suitable form, and will be found useful for some of
the usual boiler fittings to be attached to.
It will be distinctly understood that I do not intend to confine myself to the
precise details herein given and shewn in the Drawings, as such may be varied to
suit the circumstances of particular cases without departing from the main charac-
teristics of my Invention.
Having now described and ascertained the nature of my said Invention, and in
what manner the same is or may be performed, what I claim as secured to me by
the herein-before in part recited Letters Patent, is,―
Firstly. The manner by which I prevent an undue accumulation of pressure
when a safety valve lifts above the pressure at which it is set to commence to
lift, substantially as described and shown, Figures 1 and 2 of the accompanying Sheet
of Drawing,
Secondly. The use of the bent lever n for the purpose specified.
Thirdly. The method of attaching a spring to a lever operating upon two or
more valves, substantially as described and shown, Figures 3, 4, and 5 of the
accompanying Sheet of Drawing.
•
In witness whereof, I, the said Thomas Messenger, have hereunto set my
hand and seal, this Twenty-ninth day of November, in the year of our