IMPROVEMENTS IN APPARATUS FOR THE PREVENTION OF INJURIES, ACCIDENTS OR THE DESTRUCTION OF STEAM BOILERS, ARISING FROM EXCESSIVE PRESSURE OB DEFICIENCY OF WATER THEREIN."
Year: 1882

page_text: LETTERS PATENT to Arthur John Smith of Palace Chambers, Westminster,
in the County of Middlesex, Engineer, for an Invention of "IMPROVEMENTS
IN APPARATUS FOR THE PREVENTION OF INJURIES, ACCIDENTS OR THE
DESTRUCTION OF STEAM BOILERS, ARISING FROM EXCESSIVE PRESSURE OB
DEFICIENCY OF WATER THEREIN."
PROVISIONAL SPECIFICATION left by the said Arthur John Smith at the
.
Office of the Commissioners of Patents on the 27th November 1882.
ARTHUR JOHN SMITH of Palace Chambers, Westminster in the County of
Middlesex, Engineer "IMPROVEMENTS IN APPARATUS FOR THE PREVENTION OF
INJURIES ACCIDENTS OR THE DESTRUCTION OF STEAM BOILERS ARISING
EXCESSIVE PRESSURE OR DEFICIENCY OF WATER THEREIN.
"
"
FROM
The principal object of my said Invention, is to provide an efficient arrangement
of an high pressure sentinel with a low water alarm valve for steam boilers
constructed in a most simple compact & reliable form & in such a manner as
to be placed under lock & key or equivalent control so as to prevent any tampering
with the same..
For hitherto operating mechanical low water alarm valves of steam boilers, it
has been usual to employ floating bodies which follow or are caused to follow the
varying level of the water with-in the boiler but which commonly possess the
great disadvantages, that if hollow metallic casings or bodies are used as floats
there is a great liability that under continual & varying pressures that they will
ultimately collapse & or become filled with water, Whilst on the other hand if
solid bodies are desired to serve the operative functions of floats, large counter
weights & levers are usually employed, which are only suitable to some sizes &
classes of boilers, besides causing much inconvenience in fitting.

page_text: According to one part of my Invention I provide a cylindrical or orther con-
veniently shaped casing having a transverse diaphragm on which the high
pressure alarm valve is seated, the said valve being suitably loaded by a screw
plug or or similar device acting upon a spring preferably enclosed within a casing
so as to protect it from deterioration by the constant impinging of escaping steam.
In the centre of the under face of the said pressure valve I conveniently provide
the seating of the low water alarm valve, the former acting by opening upwards
by excessive pressure of steam within the boiler, whilst the latter, is effected in
the opposite direction by the action of a weight brought into play when the water
in the boiler sinks below the desired level. In this manner a very compact
valvular arrangement is obtained.
For the purpose of guiding & insuring the accurate movements of both valves, I
provide suitable guides which may be formed by a prolongation of the low water
alarm valve-spindle passing through a tubular spindle, formed on the High pressure
Alarm valve.
In constructing the casing, an intermediate diaphragm may be formed to serve
as an auxiliary bearing & for conducting the Steam clear of the afore-suiḍ
loading spring.
In the manner above-stated, the pressure valve is kept, under normal circum-
stances, seated upon the first mentioned diaphragm, by means of the spring which
may be subjected to a varying compression; whilst the low-water alarm-valve is
kept similarly seated upon the under face of the former valve, by virtue of the
back-pressure existing in the Boiler when under Steam, with the subsidiary
assistance of a small spring, weight or counterpoise, fitted within the said casing or
the Boiler, as may be desired. To the said low-water alarm-valve is connected a
suitable body, as near the specific Gravity of water as possible, so that when
immersed in the water within the Boiler, it shall exert little or no force or weight
upon the said valve; but when the level of the same sinks below the desired level,
the body, becoming suspended in the Steam-space, will then have or exert
sufficient weight or power to open the valve & thereby allow the Steam from
within the Boiler to pass to sound the whistle or alarm, situated on the valve
casing.
In practice, the difference between the specific Gravity of the Body employed as
the weight for opening the low-water alarm-valve & that of the displaced water
may be conveniently counter-balanced by a small spring or weight, suitably
located.
Ր
I further provide suitable means for ascertaining the condition of the entire
valvular mechanism from the outside of the Boiler, so as, at any time, to test
the freeness of the afore-said valves, in order to insure the reliability of the
apparatus.
It will be obviously understood, that although I have described the two alarm-
valves in combination & performing their joint functions in one apparatus, they
might, with slight modification, he separately employed & further when used in
combination the two valves could be arranged to operate side by side, both having
their seating formed in the diaphragm, in lieu of one seating in the other, as first
described.
If it be found desirable to compensate or reduce the back-pressure, exerted upon
the low-water alarm-valve, a counteracting or equilibrian valve device may be
employed.
În cases, where it is only desired to effect a low-water alarm for Steam-boilers, I
preferably employ a simple apparatus, operating in a certain manner by the effect
of variation of temperature; in lieu of the arrangement first described, acting by
virtue of displacement & Gravity.
For this purpose I may provide a sinall tube, passing through the shell of the
Boiler to the desired minimum low-water level within the same, so that the lower
end there of is, under normal circumstances, immersed in or sealed by the water,

page_text: whilst the upper end is kept closed by a valve worked by an expansion device or
a fusible plug.
The aforesaid tube or pipe is suitably insulated so as to conduct as little heat as
possible from the Boiler. By this means when the proper level of water is
inaintained within the Boiler, the Steam acting upon the surface of the same,
forces the water up the said tube until the column of air thereby compressed
within it resists further ingress.
'
In this manner the water is, under proper circumstances, kept from circulating
within the tube, so that the temperature of the same is much lower than that
within the Boiler-space, while conduction of heat is further arrested by means of
the aforesaid insulation & the column of compressed air.
When, however, the water level within the Boiler is allowed to fall below the
limits of safety, as determined by the placement of the aforesaid tube, the water
within the latter is caused to descend into the water-space of the Boiler, where-
upon the Steam is immediately caused to occupy its place & which being of much
higher temperature than the former, is caused to operate the expansion valve, or
melt the fusible plug, thereby permitting the Steam to pass to sound an alarm.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Arthur John Smith in the Great Seal Patent Office on the
25th May 1883.
ARTHUR JOHN SMITH, of Palace Chambers, Westminster, in the County of
Middlesex, Engineer, IMPROVEMENTS IN APPARATUS FOR THE PREVENTION OF
INJURIES, ACCIDENTS OR THE DESTRUCTION OF STEAM BOILERS ARISING FROM
EXCESSIVE PRESSURE OR DEFICIENCY OF WATER THEREIN
The principal object of my said Invention is to provide an efficient arrangement
of a high pressure sentinal with a low water alarm valve for steam boilers con-
structed in a most simple compact and reliable form and in such a manner as to be
placed under lock and key or equivalent control so as to prevent any tampering
with the same.
For hitherto operating mechanical low water alarm valves of steam boilers it has
been usual to employ floating bodies which follow or are caused to follow the.
varying level of the water within the boiler, but which commonly possess the
great disadvantages, that if hollow metallic casings or bodies are used as floats
there is a great liability that under continual and varying pressures that they will
ultimately collapse and or become filled with water. On the other hand if solid
bodies are desired to serve the operative functions of floats, large counter-weights
and levers are usually employed, which are only suitable to some sizes and classes
of boilers, besides causing much inconvenience in fitting.
According to one part of my Invention I provide a cylindrical or other
conveniently shaped casing having a transverse diaphragm on which the high
pressure alarm valve is seated, the said valve being suitably loaded by a screw
plug or similar device acting upon a spring preferably enclosed within a casing so
as to protect it from deterioration by the constant impinging of escaping steam.
In the centre of the under face of the said pressure valve I may conveniently
provide the seating of the low water alarm valve, the former acting by opening
upwards by excessive pressure of steam within the boiler whilst that of the latter
is effected in the opposite direction by the action of a weight brought into play
when the water in the boiler sinks below the desired level. In this manner a very
compact valvular arrangement is obtained.
For the purpose of guiding or insuring the accurate movements of both
valves, I provide suitable guides which may be formed by a prolongation of the
low water alarm valve-spindle passing through a tubular spindle formed on the
high pressure alarm valve.
In constructing.the casing, an intermediate diaphragm may be formed to serve
as an auxiliary bearing for conducting the steam clear of the aforesaid loading
spring.
In this manner as above stated, the pressure valve is kept, under normal
circumstances, seated upon the first mentioned diaphragın, by means of the spring
which may be subjected to a varying compression, whilst the low water alarm
valve is kept similarly seated upon the under face of the former valve by virtue of
the back pressure existing in the boiler when under steam with the subsidiary
assistance of a small spring, weight or counterpoise, fitted within the casing or the
shell of the boiler, as may be desired. To the said low water alarm valve is
connected a suitable body as near the specific gravity of water as possible, so that
when immersed in the water within the boiler, it shall exert little or no force or
weight upon the said valve but when the level of the same sinks below the desired
level, the body, becoming suspended in the steam space, will then have or exert

page_text: sufficient weight or power to open the valve and thereby allow the steam from
within the boiler, to pass to sound the whistle or alarm, situated on the valve
casing. In practice the difference between the specific gravity of the body
employed as the weight for opening the low water alarm valve and that of the
displaced water may be conveniently counter-balanced by a small spring or weight
suitably located, either within or outside the boiler shell.
I further provide suitable means for ascertaining the condition of the entire
valvular mechanism from the outside of the boiler, so as, at any time, to test the
freeness of the aforesaid valves in order to ensure the reliability of the apparatus.
It will be obviously understood that although I have described the two alarm
valves in combination and performing their joint functions in one apparatus they
may, with slight modifications (which will be readily understood) be separately
employed, and further when used in combination the two valves could be arranged
to operate side by side, both having their independent seating formed in the
diaphragm in lieu of one seating on or in the other, as first described.
If it be found desirable to compensate or reduce the back pressure, exerted upon
the low water alarm valve, a counter-acting or equilibrium valve device of known
construction may be employed.
In cases where it is only desired to effect a low water alarm for steam boilers, I
may employ a simple apparatus operating in a certain manner by the effect of
variation of temperature in lieu of the arrangement above described, acting by
virtue of displacement and gravity.
For this purpose I may provide a small tube, passing through the shell of the
boiler to the desired minimum low-water level within the same, so that the lower
end thereof is, under normal circumstances, immersed in, or sealed by the water,
whilst the upper end is kept closed by a valve worked by an expansion device or a
fusible plug
The aforesaid tube or pipe is suitably insulated so as to conduct as little heat as
possible from the boiler. By this means when the proper level of water is
maintained within the boiler, the steam acting upon the surface of the same, forces
the water up the said tube until the column of air thereby compressed within it
resists further ingress
In this manner the water is, under proper circumstances kept from circulating
within the tube so that the temperature of the same is much lower than that
within the boiler space, while conduction of heat is further arrested by means of
the aforesaid insulation and the column of compressed air.
When, however, the water level within the boiler is allowed to fall below the
limits of safety, as determined by the pre-determined adjustment of the aforesaid
tube, the water within the latter is caused to descend into the water space of the
boiler, whereupon the steam is immediately caused to occupy its place and which
being of much higher temperature than the former is caused to operate the
expansion valve, or melt the fusible plug, thereby permitting the steam to pass to
sound an alarm.
And in order that my said Invention may be more readily understood and
carried into effect I will now proceed to describe the essential features of same with
reference to the accompanying drawings in which fig. 1 is an elevation and
figure 2 a vertical section of a combined high pressure and low water alarm
apparatus for steam boilers constructed and operating in accordance with my said
invention; fig. 3 is a plan of the under side of same.
A is a cylindrical or other conveniently shaped casing which is provided with
the alarm whistle Z and serves as a secure and complete covering to the working
parts of the apparatus. This casing or cover screws on (or is otherwise suitably
attached) to the valve casing A¹ having a transverse diaphragm a, on which the
high pressure alarm valve b, is seated, the said valve being suitably loaded by a
screw plug e or similar device acting upon a spring d preferably enclosed within &
casing e so as to protect it from deterioration by the constant impinging of
escaping steam.

page_text: In the centre of the under face of the said pressure valve 6 I provide the seating
of the low water alarm valvef, the former acting by opening upwards by excessive
pressure of steam within the boiler, whilst that of the latter, is effected in the
opposite direction by the action of a weight g brought into play when the water in
the boiler sinks below the desired level.
33
The low water alarm actuating weight g, should be as nearly the specific gravity.
of the water that it displaces as possible.
:
In practice I find a cement or concrete float (with suitable proportions of sand
and cement to obtain the required weight) answer well. The cement weight may.
be cased over with thin metal for protective purposes.
As it is not practicable to employ any suitable substance of the exact specific
gravity as the water within the boiler, the difference I compensate for by influence
cf a small weight I (or spring), which may act on the one end of a small lever i, the
other end of which is forked as at i, and takes under a collar i̇ provided on the
lower water alarm valve spindle
For the purpose of guiding or insuring the accurate movements of both valves,
I provide suitable guides which may be formed by a prolongation f₁, of the low
water alarm valve-spindle f, passing through a tubular spindle b₁ formed on or
with the high pressure alarm valve b.
i
In constructing the valve casing A', an intermediate diaphragm h may be formed
or provided to serve as an auxiliary bearing or guide at h¹ and suitably perforated
at h2, for conducting the steam clear of the aforesaid-loading spring d, as represented
by the direction of the arrows in the drawings at Fig. 2.
.
In the manner above stated the pressure valve bis kept, under normal circum-
stances, seated upon the diaphragm a, by means of the spring d which may be
subjected to a varying compression by the loading screw plug c whilst the low
water alarm valve fis kept similarly seated upon the under face of the said former
valve by virtue of the back pressure existing in the boiler when under steam, with
the subsidiary assistance of a small weight or counterpoise I hung at the one end
of a small lever i, and fitted within the casing or shell of the boiler, as may be
desired, whilst the other end thereof engages with a collar provided on the
spindle f*. To the said low water alarm valve f is connected a suitable body or
weight g, as before described and as near the specific gravity of water as possible,
so that when immersed in the water within the boiler as indicated by the dotted
line X, Fig. 2, it shall exert little or no force or weight upon the said valve f, or its
spindle but when the level of the same sinks below the desired level (as
indicated by the dotted line Y) the body becoming suspended in the steam space of
the boiler will then have or exert sufficient weight or power to open the valve and
thereby allow the steam from within the boiler to pass to sound the whistle or
alarm Z, situated on the valve casing A. In practice the difference between the
specific gravity of the body employed as the weight for opening the low water
alarm valve and that of the displaced water may be conveniently counterbalanced
or compensated for by the small weight I, suitably located as before described.
I further provide suitable means for ascertaining the condition of the entire
valvular mechanism from the outside of the boiler, so as, at any time, to test the
freeness of the aforesaid valves, in order to insure the reliability of the apparatus.
This means consists in prolonging the tubular spindle b' through the spring
loading plug c, and providing it with a hexagonal or square termination t so as to
allow it to be moved or turned by means of a spanner or other suitable tool in
order to clear the high pressure valve 6 upon its seating, whilst the prolongation f¹
of the low water alarm valve is continued through the aforesaid tubular spindle 6',
for a sufficient length to clear the hexagonal termination t, above mentioned, and
as shewn at f, for the purpose of clearing the low water alarm valve upon its
seating and in its bearings by depressing the same.
The manner and direction the steam finds access from the boiler to the alarm is
indicated by the arrows. It will be seen that the low water alarm valve spindle
is reduced at k so as to allow the steam when the said valve is opened to pasa

page_text: round and find egress through the apertures provided through the high pressure
valve as shewn. But I would have it understood that I do not limit myself to
these precise details for allowing the passage of steam as I may allow the same to
go direct through the tubular spindle 6' to the alarm.
It will be readily understood that although I have described the two alarm
valves in combination and performing their joint functions in one apparatus, they
may, with slight modifications, be separately employed, and further, when used in
combination, the two valves could be arranged to operate side by side, both having
their seating formed in the diaphragm a, in lieu of one seating in the other, as
above described.
If it be found desirable to compensate or reduce the back pressure, exerted upon
the low water alarm valve, a counter acting or equilibrium valve device may be
employed.
Having now described the nature of my Invention and the manner in which the
same may be performed I declare that I claim,
1. The combined high pressure and low water alarm valve or apparatus for
steam boilers, or other similar purposes, constructed and operating substantially as
and for the purposes herein before described with reference to the accompanying
drawings.
2. In alarm apparatus for steam boilers as above set forth, the combination of
the low water alarm valve working within the high pressure valve, arranged and
operating substantially as hereinbefore described with reference to the accompanying
drawings.
3. In alarm apparatus as set forth in the preceding claims operating the low
water aların valve by a body or weight as near the specific gravity of the water
displaced as possible, so as only to require very slight compensation, substantially
as herein before described with reference to the accompanying drawings.
In witness whereof I the said Arthur John Smith have hereunto set my
hand and seal this Twentythird day of May in the year 1883.
ARTHUR JOHN. SMITH. (L.S.)