Improvements in Low-water Alarms and Indicators for Steam Boilers and similar Vessels.
Year: 1890

page_text: Date of Application, 17th Feb., 1890-Accepted, 29th Mar., 1890
L
COMPLETE SPECIFICATION.
Communicated from abroad by EDWARD EDMUND KILDOYLE, of Yokohama, in the
Empire of Japan, Engineer.]
Improvements in Low-water Alarms and Indicators for Steam
Boilers and similar Vessels.
I, ALFRED FRANCIS TOOVEY of 7 Commercial Buildings Newcastle-upon-Tyne in
the County of Northumberland, Engineer do bereby declare the nature of this inven-
tion, and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
This Invention relates to apparatus constructed and arranged to give an audible or
visible indication signal or alarm when the level of the water or other liquid in a
steam boiler or similar vessel falls below a pre-determined level.
According to these Improvements there is attached to the shell of the boiler or to
the wall or shell of the similar vessel, a closed chamber having a comparatively large
surface in relation to its internal capacity. This closed chamber includes a pot dish
or similar receptacle and its interior communicates with the interior of the boiler or
other vessel. The pot is arranged within the closed chamber so as to be heated by
the fluid therein and it is filled with an alloy or material which is hard and firm at
ordinary temperatures and which melts at the temperature of the steam or vapour of
the fluid contained in the boiler. Near the bottom of the pot there is pivoted or
similarly secured the lower end of a vertical arm to the upper end of which there
may be attached a weight or spring the tendency of which will be to pull the vertical
arm into an angular position. At any temperature less than that of the steam con-
tained in the boiler, the vertical arm is embedded in the fusible alloy or material and
the tendency of the weight or spring to pull it into an angular position is resisted.
So soon however as the level of the water or of the liquid falls below the inlet to the
chamber and the steam obtains access therefo, the alloy or material contained in the
pot is melted and the weight or spring at once operates to pull over the vertical arm
and this motion may be employed to open a steam whistle, to ring a bell, to close an
electric alarm circuit, or otherwise to actuate an audible or visible alarm or signal or an
indicator as is well understood.
A separate opening may be made in the closed chamber into which there may be
inserted a pipe or tube connected to a steam alarm which may be situated in any
convenient position as for example in the manager's office.
It will be understood because of the comparatively large surface of the closed
chamber, the liquid contained therein is at a lower temperature than that of the steam
arising therefrom within the boiler, and that when the level of the liquid falls so that
the steam has access to the interior of the chamber, the temperature within the
closed vessel is raised to that of the steam. The alloy or other fusible material
contained within the pot must be of such a character that it is solid when the
chamber contains water or other liquid only and melts when the steam obtains access
thereto.
I will now proceed to more particularly describe my said Invention with reference
to the accompanying drawing which represents a longitudinal section of an apparatus
constructed according to these Improvements.
A is the front or shell of the boiler or other vessel to which the closed chamber B
is attached. The interior of the boiler communicates with the interior of the
chamber B by means of the openings CC or by means of a vertical slot having
a length nearly equal to the vertical diameter of the chamber, or by an opening
having about the same area as the cross section of the chamber. D is the dish
or pot secured within the upper part of the chamber; E is a vertical arm pivoted
at F or resting upon the bottom of the pot; and W is a weight (which may be

page_text: substituted by a spring) attached to the upper part of the arm E with a tendency to
pull the vertical arm into an angular position.
The pot being filled with a fusible alloy, with sulphur, or with other fusible
material having the character hereinbefore described, and the arm E being in the
vertical position indicated in the drawing, it will be retained in that position by
the surrounding solid material until this is melted, when the weight (or spring)
will at once pull the arm over. This motion is utilised to operate an alarm signal
or indicator as herein before described.
If it be desired that the apparatus should actuate a steam alarm, an inlet G may
be formed in the wall of the chamber B through which, by means of suitable pipes,
the steam alarm may be connected to the interior of the chamber. This opening
should be in the upper part of the chamber so that the alarm may be actuated as
soon as steam enters the chamber owing to the fall in the level of the liquid.
The pot or dish D containing the fusible alloy has been described as being arranged.
at the upper part of the chamber and this is the arrangement which it is preferred
to adopt but it may be arranged at one side or even at the bottom of the chamber if
desired, in which case some or all the fusible material would escape at each operation.
of the apparatus and would have to be replaced in re-setting it.
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;-
(1) A low water alarm or indicator constructed arranged and operating substantially
as hereinbefore described and as illustrated by the accompanying drawing.
(2) In a low water alarm or indicator, the combination and arrangement of a closed
chamber communicating with the interior of the boiler or other vessel, a pot or
receptacle containing a fusible material, and an arm arranged to be moved or to fall
upon the melting of the fusible material; substantially as and for the purpose herein-
before described and as illustrated by the accompanying drawing.
Dated this 12th day of February A.D. 1890.
WILLIAM E. HEYS,
Agent for the Applicant.