Improvements in Apparatus for Preventing Danger to Steam Boilers in the Event of Shortness of Water.
Year: 1892

page_text: Date of Application, 7th Jan., 1892
Complete Specification Left, 24th Mar., 1892-Accepted, 30th Apr., 1892
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Preventing Danger to Steam Boilers
in the Event of Shortness of Water.
I THOMAS GRAY PARKINSON of 35 Colmore Row, Birmingham, Local Secretary,
Westminster Fire Office do hereby declare the nature of my said invention to be as
follows:-
I provide a metallic chamber as described below, and fix it so that its lowest
part is at a convenient height, say two and a half feet, above the normal water level
in the boiler. This chamber is usually of cast iron, though wrought iron, steel, or
other metal may be used. And it must be strong enough to withstand a steam
pressure equal to that in the boiler with which the apparatus is connected. It is
approximately cylindrical in shape and of a length about ten times its diameter,
the axis lying horizontally. The lower part of the chamber is inclined and depressed
somewhat into the shape of a funnel or tun dish. This lower part of the chamber
is connected to the boiler by a pipe which enters the boiler at a point a few inches
below the normal working water level but about three inches above the furnace or
flue in an internally fired boiler, or at a corresponding height in an externally fired
boiler, that is to say at a point a few inches above what would be a dangerous
water level. At the top of the chamber I provide a cock by means of which it
may be emptied of air, if necessary, when starting the apparatus. I provide a steel
tube preferably solid drawn. This tube is about one inch diameter, and of metal
as thin as is consistent with ample strength to resist the steam at boiler pressure.
The length is the same as that of the chamber. This tube I fix inside the chamber.
It extends axially along the chamber, to which it is securely scaled at each end
by tightly screwing or by other well known mechanical means. The tube is open
at both ends. I provide a bar or rod of metal which is very sensitive to heat but
which will not melt at the temperature of the boiler steam. This metal must be
such that the expansion caused by heat is greater than that of the iron or steel of
which the chamber and tube are made, with an equal rise in temperature.
I may
use brass or zinc or other metal for this rod.
This rod of metal, which I call the expansion rod, is of such an external diameter
that it nearly fills the steel tube previously mentioned. I make it a little longer
than the tube and I place the expansion rod inside the tube and firmly secure one
end thereto, preferably by a pin of sufficient strength passing diametrically through
the metal of the one end of the chamber and one of the ends of the tube and the
expansion rod. The free end of the expansion rod will then project a little way
beyond the other end of the steel tube.
I provide a lever of the first or third order of which one arm is very much longer
than the other. The fulcrum of this lever is affixed to that end of the chamber at
which the free end of the expansion rod emerges from the steel tube. The lever
stands vertically and its upper end is in contact with the free end of the expansion
rod previously described. "It is kept in contact therewith by a suitable adjustable.
helical spring.
The lower end of the lever has of course a motion greater than the upper end
in proportion to the difference in the length of the arms of the lever. The lower
end of the lever presses against a cam or projecting piece mounted on a spindle
above a valve. This valve is enclosed in a suitable casing placed below the chamber
first-mentioned but well above the normal water level of the boiler. The under side
of the valve is in connection with the boiler through a second pipe which enters the
boiler about an inch below the pipe previously mentioned as establishing communi-
cation between the boiler and the cylindrical chamber. The upper side of the valve
is in communication with a third pipe which is led downwards into the furnace, the

page_text: free end of this pipe above the fire. The spindle carrying the cam actuated by
the lever passes through, or nearly through, the valve casing. Where the spindle
passes through the side of the casing I provide an ordinary stuffing box and gland.
I affix to the spindle where it passes nearly above the valve a projecting cam
like the one outside the casing which latter is actuated by the lever. In normal
working the cám above the valve presses on it and keeps it shut.
On the spindle I cut a helical groove of very quick pitch, and I provide a
projection in the casing, taking into this groove so that when the spindle is caused
partially to rotate it has given to it an end long movement.
The end of the spindle which projects from the casing is made square so that it
can be caused partly to rotate by means of a suitable key. I provide preferably a
lock up outer casing for the whole or part of the apparatus so that when once
adjusted it cannot be tampered with, without the knowledge of the person possessing
the key. In the outer casing opposite to the square end of the spindle previously
mentioned, is a slip of glass which is broken by the end of the spindle when that is
caused to project outwards as I shall describe. To set the apparatus at work the
water in the boiler is brought to the normal working level that is above both the
lower and orifices of the pipes communicating to the apparatus.
Steam is then raised in the boiler, and by its pressure it gradually forces some
of the water up the pipe into the chamber above the boiler, where it will be retained
by the pressure of the steam on the surface of the water in the boiler. As the water
rises into the chamber it grows cool as there is, what is commonly called a
"dead
end," that is no circulation.
As long as the level of the water in the boiler remains above the lower orifice of
the pipe communicating with the chamber, the cool water in the latter will be
retained in its position. The lever will also remain in such a position that the valve
is kept closed.
If, however, the water level in the boiler falls below the lower orifice of the pipe
leading to the chamber, then the cool water in the chamber is no longer retained in
its position, but it flows out of the chamber (its flow being accelerated by the shape
of the lower part of the chamber) and down into the boiler. The chamber is then
filled with live steam of a high temperature from the boiler. This heats the steel
tube which passes through the chamber, and this in turn communicates its heat to
the expansion rod. As the heat causes, the expansion rod to increase in length, the
free end pushes against the upper end of the lever. The lower end of the lever
moves away from and releases the cam from the spindle. The valve which has
the boiler pressure on its under side is then free to open as the cam which held it
down is secured to the same spindle as the cam released by the lever. When this
valve rises and opens, it allows water to rise up the second, that is, the lower pipe
from the boiler, this water passes through the open valve, into the casing, and is
then led by the third pipe into the furnace, where it falls upon the fire and
extinguishes it wholly or in part. When the valve rises it actuates the cam above
it and gives to the spindle on which the cam is secured a partial rotatory motion.
By means of the helical groove and the projection taking into it the spindle, has an
end-long motion given to it and its outer or square end breaks the glass in the
outer casing. When the attendants attention is aroused he finds that the square
end of the spindle is now rendered accessible by the breaking of the glass. He
applies his key thereto by a movement of partial rotation he closes the valve and
stops the flow of the water on to the fire.
The position of the pipe from the boiler to the under side of the valve is such
that it will only take water to the depth of one inch out of the boiler, it then
takes steam. So that if any accident should occur to a water guage glass at
night or the attendant be taken ill it would still leave one inch depth of water over
the furnace or flue.
Dated 7th Janua1901

page_text: COMPLETE SPECIFICATION.
Improvements in Apparatus for Preventing Danger to Steam Bollers
in the event of Shortness of Water.
I, THOMAS GRAY PARKINSON, of 35 Colmore Row, Birmingham, Local
Secretary, Westminster Fire Office, do hereby declare the nature of my said invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
I provide a metallic chamber as described below, and fix it so that its lowest
part is at a convenient height, say wo and a half feet, above the normal water
level in the boiler. This chamber is usually of cast iron, though wrought iron,
steel, or other metal inay be used. And it must be strong enough to withstand a
steam pressure equal to that in the boiler with which the apparatus is connected.
It is approximately cylindrical in shape and of a length about ten times its
diameter, the axis lying horizontally. The lower part of the chamber is inclined
and depressed somewhat into the shape of a funnel or tun dish. This lower part
of the chamber is connected to the boiler by a pipe which enters the boiler at a
point a few inches below the normal working water level but about three inches
above the furnace or flue in an internally fired boiler or at a corresponding height
in an externally fired boiler, that is to say at a point a few inches above what
would be a dangerous water level. At the top of the chamber I provide a cock,
by means of which it may be emptied of air, if necessary, when starting the
apparatus. I provide a steel tube preferably solid drawn. This tube is about one
inch diameter, and of metal as thin as is consistent with ample strength to resist
the steam at boiler pressure. The length is a little more than that of the chamber.
This tube I fix inside the hamber. It extends axially along the chamber, to
which it is rigidly secured a. one end, and fastened by a flexible diaphragm at the
other. The tube is closed at one end. I provide a bar or rod of metal which is
very sensitive to heat but which will not melt at the temperature of the boiler
steam. This metal must be such that the expansion caused by heat is greater
than that of the iron or steel of which the chamber and tubes are made, with an
equal rise in temperature. I may use brass or zinc or other metal which will
fulfil these conditions for this rod.
This rod of metal, which I call the expansion rod, is of such an external diameter
that it nearly fills the steel tube previously mentioned. I make it a little longer
than the tube and I place the expansion rod inside the tube and firmly secure one
end thereto, preferably by a pin of sufficient strength passing diametrically through
the metal of the one end of the chamber and one of the ends of the tube and the
expansion rod. The free end of the expansion rod will then project a little way
beyond the other end of the steel tube.
I provide a lever of the first or third order of which one arm is very much
longer than the other. The fulcrum of this lever is affixed to that end of the
chamber at which the free end of the expansion rod emerges from the steel tube.
The lever stands vertically and its upper end is connected with the free end of the
expansion rod previously described. It is kept in contact therewith by a suitable
screw with adjusting lock nuts.
The lower end of the lever has of course a motion greater than the upper end
in proportion to the difference in the length of the arms of the lever. The lower
end of the lever presses against a cam or projecting piece mounted on the spindle
of a valve. This valve is enclosed in a suitable casing placed below the chamber
first-mentioned but well above the normal water level of the boiler. The under
side of the valve is in connection with the boiler through a second pipe which
enters the boiler about an inch below the pipe previously mentioned as establishing
communication between the boiler and the cylindrical chamber. The upper side
of the valve is in communication with a third pipe which is led downwards into

page_text: the furnace, the free end of this pipe is above the fire. The outer end of the
spindle carrying the cam actuated by the lever passes outward through the valve
casing. Where the spindle passes through the casing I provide an ordinary gland.
I affix to the spindle outside the valve casing a projecting cam which is controlled
by the lever. In normal working the lever being in contact with the cam presses
on it and keeps the valve closed.
"
The end of the spindle which projects from the casing is made square so that it
can be caused partly to rotate by means of a suitable key. On the spindle is a
disc showing the words "Operating or "Not operating" through an aperture
in the outer casing. I provide preferably a lock-up outer casing for the whole or
part of the apparatus so that when once adjusted it cannot be tampered with,
without the knowledge of the person possessing the key. In the outer casing
opposite to the square end of the spindle previously mentioned, is a slip of glass
which is broken by the end of the spindle when it is caused to project outwards
as I shall describe. To set the apparatus at work the water in the boiler is
brought to the normal working level that is above both the lower orifices of the
pipes communicating to the apparatus.
Steam is then raised in the boiler, and by its pressure it gradually forces some
of the water up the pipe into the chamber above the boiler, where it will be
retained by the pressure of the steam on the surface of the water in the boiler.
As the water rises into the chamber it grows cool as there is, what is commonly
called a "dead end," that is-no circulation.
As long as the level of the water in the boiler remains above the lower orifice
of the pipe communicating with the chamber, the cool water in the latter will be
retained in its position. The lever will also remain in such a position that the
valve is kept closed.
If, however, the water level in the boiler falls below the lower orifice of the
pipe leading to the chamber, then the cool water in the chamber is no longer
retained in its position, but it flows out of the chamber (its flow being accelerated
by the shape of the lower part of the chamber) and down into the boiler. The
chamber is then filled with live steam of a high temperature from the boiler. This
heats the steel tube which passes through the chamber, and this in turn com-
municates its heat to the expansion rod. As the heat causes the expansion rod to
increase its length, the free end pushes against the upper end of the lever. The
lower end of the lever moves away from and releases the cam on the valve spindle.
The valve, which has the boiler pressure on its under side, is then free to open,
as the cam which held it on its seat is secured to its spindle. When this valve
opens, it allows water to rise up the second, that is, the lower pipe from the boiler,
this water passes through the open valvc, into the valve casing, and is thence led
by the third pipe into the furnace, where it falls upon the fire and extinguishes it
wholly or in part. When the attendants attention is aroused he finds that the
square end of the spindle is now rendered accessible by the breaking of the glass.
He applies his key thereto and by a movement of partial rotation he brings the
words "Not operating on the disc into sight. When the attendant re-sets the
apparatus he again brings the words "Operating" into sight.
"
The position of the pipe from the boiler to the under side of the valve is such
that it will only take water to the depth of one inch out of the boiler, it then takes
steam. So that if any accident should occur to a water gauge glass at night or
the attendant be taken ill it would still leave one inch depth of water over the
furnace or flue.
And in order that this my said invention may be more clearly understood, I
will now proceed to describe the same aided by the accompanying sheet of drawings.
The same letters of reference denote the same parts in every figure in which they
occur:
Fig. 1, is a front sectional elevation of the apparatus complete, with the outer
casing removed, and part of the steam-boiler shown in section.
Fig. 2. is a front elevation with the casino on.

page_text: Fig. 4, is an end elevation with the casing on.
Fig. 5, is a front elevation of the principal part of the apparatus, to a larger
scale.
Fig. 6, is a plan of the same part as that shown in Fig. 5, and to the same scale.
Fig. 7, is a view of the cam detached.
Fig. 8, is a cross section through tube and expansion rod.
a is the metallic chamber, fixed at a convenient height above the boiler 8, b is a
metallic cap closing one end of the chamber a. c is a pin fastening together the
cap b one end of the thin tube a' and the expansion rod a². d is a diaphragm of
metal, secured at its circumference to the cape and at its centre to the end of the
tube a'. The cap e is screwed into the end a³ of the chamber a. f is a screwed
rod, forming a continuation of the expansion rod a² and provided with four lock
nuts f; g is a fulcrum on the chamber a. is a lever having an eye at the upper end,
through which passes the screwed rod f the position of the end of the lever is
adjusted by the lock nuts f¹. j is a pipe, connecting the chamber a to the boiler s.
It enters the boiler a few inches (say three or four) below the normal water level t.
k is a pipe opening into the boiler, a little below j and leading to a valve chamber
which it enters at the "underside" of the valve l. By the underside is to be under-
The valve is
stood, that side of the valve upon which the boiler pressure comes.
provided with a spindle 2 which passes out of the valve casing through a suitable
gland. On this spindle is secured a cam m and a disc n which bears the words
Operating" and "Not operating" on the same face, but diametrically opposite to
66
each other.
The outer end of the spindle, is made square, 13 is a set off on the spindle, to
prevent its being driven too far out by the steam pressure on the valve.
o is a slip of glass in the casing p opposite the end of the valve spindle P². The
casing p covers the apparatus and is locked by a padlock pl or other suitable lock,
so that when once set, the apparatus cannot be tampered with. g
connecting different parts of the apparatus.
is
a bar
ris a pipe leading from the space in the valve chamber above the valve
downward to the furnace.
s is the boiler, t the normal water level, t¹ the low water level, u u are boiler
tubes.
The action of the apparatus is as follows. The water in the boiler being at its
normal level t, steam is raised, and by its pressure it forces water out of the
boilers, up the pipe j into the chamber a which it gradually fills. The air in a
may be suffered to escape through a cock at a. The air cock at being then
closed.
The water is retained in the chamber a by the pressure of the steam on the
surface of the water in the boilers, there being no circulation the water in a is
cool, water is also forced up the pipe into the valve chamber in the same
manner.
The upper end of the lever h¹ is adjusted in its position by the lock nuts f1f1
so that its lower end is in contact with the cam m on the valve spindle, so that
it keeps the valve l' closed.
The water in the chamber a surrounds the thin tube a¹ which is secured rigidly
to one end of the chamber by the pin c and by a flexible diaphragm d to the cap e
at the other end. The expansion rod a which is inside the tube a¹ will be of the
same temperature as the water in the chamber a.
Should the boiler become short of water, the apparatus acts as follows:-As
soon as the water level falls below the cool water in the chamber a flows down
the pipe into the boiler, its place is filled by boiler steam which is of a much
higher temperature than the water which the chamber a was previously filled.
This steam communicates its heat through the metal of the tube a¹ to the
expansion rod a' although of course the whole of the chamber a and the tube a¹
expand with the heat, yet as the rod a' is made of a metal which expands more

page_text: This will
than that of the chamber a under the same increment of heat the screwed end f
will move outwards carrying the upper end of the lever with it.
cause a motion of the lower end
of the lever in the opposite direction as shown
by the arrow, this motion being increased in the proportion of the respective
lengths of the arms of the lever. The motion of the end h of the lever releases
the cam m, and the pressure of the steam on the surface of the water in the boiler
drives the water in the pipe k and the valve chamber through the valve which is
now free to open, and down the piper by which it is led on to the fire in
furnace which it extinguishes partly or wholly, thus preventing any chance of
explosion.
When the valve is released and opened by the steam pressure by the water
behind it, the spindle is driven forward and its outer end breaks a slip of glass o
in the casing p. The end of the spindle is then accessible to the attendant, and
being square, he can turn it half way round by means of a suitable spanner, the
effect of this is to cause the words "Not operating on the disc o to come into
sight at the aperture p² of the casing p.
"
37
The disc retains its position and shows these words until the apparatus is once
more set in going order, when the attendant half rotates the disc again and shews
the words "Operating.' The means which I now describe for releasing the valve
and causing the movement of the spindle are somewhat different from those
described in my Provisional Specification having been found better adapted for
the purpose.
The above being my said invention, I would observe in conclusion that I do not
limit myself to the precise details, but that I may alter or modify the same without
departing essentially from the principle of my said invention.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1st. In "Apparatus for preventing danger to steam boilers in the event of
shortness of water," the combination with the boiler, of a pipe carrying a chamber
with a tube, and an expansion rod located in the latter, both secured at one end of
said chamber, but projecting at opposite end of said chamber, carrying adjustable
lever, engaging a cam, connected with valve, substantially as and for the purpose
set forth.
2nd. In "Apparatus for preventing danger to steam boilers in the event of
shortness of water," the combination with above described, of a pipe, with the
boiler, carrying a valve chamber, with valve, said valve being provided with
spindle, upon which is said cam, substantially as and for the purpose set forth.
"
3rd. In "Apparatus for preventing danger to steam boilers in the event of
shortness of water" the combination with above described of a pipe from valve
chamber to the fire. Upon said spindle with cam, a disc, with words "Operating
and "Not operating." A casing, with slip of glass in same, opposite to outer end
of spindle, substantially as and for the purpose set forth.
4th. In "Apparatus for preventing danger to steam boilers in the event of
shortness of water the general combination and arrangement of parts substan-
tially as and for the purpose as herein before described, in the foregoing
Specification and illustrated on the accompanying sheet of drawings.
Dated 24th March 1892.
THOS. KENDRICK,
Agent.