IMPROVEMENTS IN LOW WATER ALARMS FOR STEAM BOILERS AND OTHER RECEPTACLES FOR LIQUID UNDER PRESSURE
Year: 1876

page_text: LETTERS PATENT to George Kelson Stothert and Edward Joseph Curtin, both
of Bristol, in the County of Gloucester, for the Invention of "IMPROVEMENTS
IN LOW WATER ALARMS FOR STEAM BOILERS AND OTHER RECEPTACLES FOR
LIQUID UNDER PRESSURE."
ealed the 25th July 1876, and dated the 12th February 1876
PROVISIONAL SPECIFICATION left by the said George Kelson Stothert and
Edward Joseph Curtin at the Office of the Commissioners of Patents on the
12th February 1876.
GEORGE KELSON STOTHERT and EDWARD JOSEPH CURTIN, both of Bristol, in
the County of Gloucester. "IMPROVEMENTS IN LOW WATER ALARMS FOR STEAM
BOILERS AND OTHER RECEPTACLES FOR LIQUID UNDER PRESSURE."
According to our Invention we arrange at some distance above the water level of
the steam boiler or other receptacle for liquid under pressure a closed chamber com-
municating at its lower end with the water space of the boiler by means of a pipe,
which is made to pass down to the low water level. In the chamber is a float, by
preference a hollow metal sphere, but which may be of any other suitable shape
and material that will float in water. At the top of the chamber is an opening
communicating with a steam whistle, the opening being closed by a cock or valve.
The operation of the apparatus is as follows:-Assuming the water in the boiler
to stand at its proper level the steam pressure will force the water up through the
pipe into the chamber, filling the same, and causing the float to rise and act upon
the cock or valve so as to close it. When the water sinks below the proper level in
the boiler, the mouth of the pipe being uncovered, the water will flow out of the
vessel and pipe, and the float in falling will allow the valve to open, and con-
sequently the alarm whistle will be sounded.
In order to cause the cock or valve to open readily when not acted upon by the
float it may either be weighted, or it may be acted on by a spring, or it may be
connected to the float by a hinge joint, or by a cradle, upon which the weight of
the float rests when there is no water in the chamber. Instead of causing the float
to act directly on the cock or valve it may be connected to a lever, which is made
to act thereon.
According to another arrangement we employ in place of the before-described
float a piece of metal, such as platinum, brass, or copper, that will expand consider-
ably under the action of heat. This piece of metal is attached to a cock or valve

page_text: communicating with the alarm whistle, or to a lever connected to the cock or valve,
and is so arranged that when the chamber is filled with water the piece of metal
being comparatively cool, and consequently contracted, it will hold the valve closed,
while when the water flows out of the chamber as before described, and is filled
with steam, the heat will cause the metal to expand sufficiently to open the cock or
valve.
SPECIFICATION. in pursuance of the conditions of the Letters Patent filed by the
said George Kelson Stothert and Edward Joseph Curtin in the Great Seal
Patent Office on the 27th July 1876.
GEORGE KELSON STOTHERT and EDWARD JOSEPH CURTIN, both of Bristol, in
the County of Gloucester. "IMPROVEMENTS IN LOW WATER ALARMS FOR STEAM
BOILERS AND OTHER RECEPTACLES FOR LIQUID UNDER PRESSURE."
According to our Invention we arrange at some distance above the water level
of the steam boiler, or other receptacle for liquid under pressure, a closed chamber,
communicating at its lower end with the water space of the boiler by means of a
pipe which is made to pass down to the low water level. In the chamber is a float,
by preference a hollow metal sphere, but which may be of any other suitable shape
and material that will float in water. At the top of the chamber is an opening
communicating with a steam whistle, the opening being closed by a cock or valve.
The operation of the apparatus is as follows:-Assuming the water in the boiler
to stand at its proper level, the steam pressure will force the water up through the
pipe into the chamber, filling the same and causing the float to rise and act upon
the cock or valve so as to close it. When the water sinks below the proper level in
the boiler, the mouth of the pipe, being uncovered, the water will flow out of the
vessel and pipe, and the float in falling will allow the valve to open, and con-
sequently the alarm whistle will be sounded.
In order to cause the cock or valve to open readily when not acted upon by the
float it may either be weighted, or it may be acted on by a spring, or it may be
connected to the float by a hinge joint, or by a cradle, upon which the weight of
the float rests when there is no water in the chamber. Instead of causing the float
to act directly on the cock or valve it may be connected to a lever, which is made
to act thereon.
According to another arrangement we employ in the place of the before described
float a piece of metal, such as platinum, brass, or copper, that will expand con-
siderably under the action of heat. This piece of metal is attached to a cock or
valve communicating with the alarm whistle, or to a lever or levers connected to
the cock or valve, and is so arranged that when the chamber is filled with water
the piece of metal being comparatively cool and consequently contracted it will hold
the valve closed, while, when the water flows out of the chamber as before described,
and is filled with steam, the heat will cause the metal to expand sufficiently to open
the cock or valve.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 is a vertical section of one form of low water alarm, according to our
Invention applied to a steam boiler. A is a pipe dipping down into the water of
the boiler and communicating with a vessel B, in which is placed a float C, having
a stein attached to a valve D. When the float is kept up by the water occupying
the vessel B the valve D closes the passage to a whistle E, but should the water in
the boiler sink below the level of the mouth of the pipe A then the water will flow
out of the vessel B, and its place will be supplied by steam. The float C being
then no longer supported will descend, opening the valve D, and the steam issuing
through the whistle will cause it to sound an alarm. The valve D instead of being
attached to the float may simply be borne upwards by it in opposition to a spring

page_text: or weight of force sufficient to open the valve against the steam pressure, but not
sufficient to open it against that pressure when aided by the buoyancy of the
float.
Fig. 2 represents a vertical section of a construction in which the float C is
mounted on an axis c, and acts with leverage on the valve D connected to it by a
rod d.
Fig. 3 represents a construction in which the expansion and contraction of a rod
F, resulting from variation of temperature, is substituted for the descent and ascent
of a float. In this case the boiler pipe A communicates with a tall vessel B, in
which is a rod F of different metal from that of the vessel B, so that when the
temperature is raised the rod F expands somewhat more in length than the sides of
the vessel. To the rod F is attached the valve D, governing the passage to the
whistle E. A cavity G is provided for giving access to the end of the rod F, and
to a nut f, whereby its length can be accurately adjusted so as to close the valve D
when the vessel B is charged with water. Should this water be replaced by steam
the rod F expanding will cause the valve D to open, and the whistle will be
sounded by the escaping steam. It may be readily understood that the rod F
instead of acting directly on the valve D might be arranged to act thereon through
a lever or levers so as to multiply the amount of movement resulting from its
expansion.
Having thus described the nature of our Invention, and in what manner the
same is to be performed, we claim,—
First. The use as a low water alarm for a steam boiler of a float in a vessel
communicating with the water of the boiler in combination with a valve or cock,
and a whistle so arranged and operating that when the water in the boiler sinks
below a determined level, and the vessel becomes emptied of water, then the descent
of the float opens the passage to the whistle, causing it to sound substantially as
herein described.
Second. The use as a low water aların for a steam boiler of a rod in a vessel
communicating with the water of the boiler in combination with a valve and
whistle so arranged and operating that when the water of the boiler sinks below a
determined level, and the vessel becomes charged with steam, then the expansion of
the rod, due to increase of temperature, opens the passage to the whistle, causing it
to sound substantially as herein described.
In witness whereof, we, the said George Kelson Stothert and Edward Joseph
Curtin, have hereunto set our hands and scals, this Twenty-second day of
July, in the year of our Lord One thousand eight hundred and seventy-six.