Electric Low-water Alarm for Steam Boilers.
Year: 1893

page_text: Date of Application, 19th June, 1893
Complete Specification Left, 3rd Feb, 1894-Accepted, 14th Apr., 1894
PROVISIONAL SPECIFICATION.
Electric Low-water Alarm for Steam Boilers.
RICHARD BROWN No. 43 Milner Street, Preston, Lancashire, Pattern Maker
and Draughtsman, do hereby declare the nature of this invention to be as
follows:-
That by means of steam and water in boiler being brought in contact with a
column of mercury, so as to influence its rising and falling (as in a thermometer)
the steam and water acting alternately on it, as the water rises and falls,-by the
bigher temperature of steam, the mercury is caused to rise, as to make contact with
two wire-ends sealed in mercury tube, thereby connecting the two together,
completing the electric circuit, causing the electric bell to ring so as to warn the
attendant.
Dated thie 17th day of In 1902
RICHARD BROWN.
COMPLETE SPECIFICATION.
Electric Low-water Alarm for Steam Boilers.
I, RICHARD BROWN, of 43 Milner Street, Preston, in the County of Lancaster,
Pattern Maker and Draughtsman, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The nature of this invention has reference to the further safety of steam boilers,
and to prevent the great destruction caused to them, through shortness of water;
mainly owing to neglect or oversight of the attendant. My apparatus is intended
to meet these requirements, by an automatic ringing of an alarm when the water
becomes low, and consists of:-
An arrangement by steam and water in boiler being brought in contact with a
column of mercury, so as to influence its rising and falling (as in a thermometer) ;
the steam and water from boiler acting alternately on it, as the water rises
and falls.
By the higher temperature of steam the mercury is caused to rise, so as to make
contact with two wire ends sealed in mercury tube, thereby mercurially connecting
the two together, completing the electric circuit, causing the electric bell to ring,.
thus warning the attendant.
Fig. 1 in the accompanying drawings is a section of boiler, shewing general
arrangement of my electric low water alarm, as above described applied
thereto.
Fig. 2 is a large section of round shaped instrument or fitting e, shewing details,
with mercury tube and wire connections.
In Fig. 1a is the boiler, the water shewn by dotted lines. Pipe is connected to
the outer shell of boiler a at any point which may be deemed that of low water, and
may project into it (as shewn). On the uppermost part of pipe b is attached
fitting e, coupled to it is a blow through piped with a stop cock e for blowing steam
or water through at any time to test the passage.
In Fig. 2 the details consist of main body, having screwed into the top of it a
pipe shaped seating g (for mercury tube), which has two flat sides at the upper part
D

page_text: for the purpose of applying a spanner, so as to screw in, and make a steam and water
tight joint. On body is a shell casing fastened by screws i¹, to which are
attached insulating bushes j j¹ in combination with terminals k k (as shewn) for
connecting wires through to bell and battery. is a plug screwed into top of
casing allowing for packing round upper portion of mercury tube and other
purposes. The mercury tube m, with the column of mercury in it, has two wire
ends n n' inserted and sealed into it, the said wires being connected to terminals k k¹
and continued to bell and battery. The connections of pipe b and d are also
shewn.
Now the boiler being under pressure, the working level of water in, and the
apparatus all complete and attached; all that is required is for the wire ends n n'
to be mercurially connected to ring the alarm. This is effected in the following
manner :-
The pipe being connected to water in boiler a (see Fig. 1), so long as the con-
nection is maintained, the water is forcibly kept up into pipe and body of fitting c,
forming a column of water outside of boiler a, the temperature of which is reduced
by the overwhelming cooling surface exposed to the atmosphere, to that of heating
Eurface, thus keeping the mercury from contact with wire ends n n. When
however the water becomes low and disconnected from pipe, the water in it-by
its gravity falls back again, and said pipe being then open to steam is
instantaneously filled, and the higher temperature of the steam acting on the column
of mercury (through seating g) causes the mercury to rise so as to make contact
with the two wire ends nn, mercurially connecting them, thereby completing the
electric circuit and causing electric bell to ring. The alarm having drawn attention,
the bell may be switched off until the water is replaced, when, by the aforesaid
action of reduced temperature of the water, the mercury falls, and disconnects wire
ends, as will be well understood.
In boilers where the water is not of that sedimentary character as to require a
blow through pipe, it may be dispensed with.
When it is preferable to form earth connection instead of wiring throughout for
electric circuit, this is effected by one insulated terminal being fixed into plug l
(Fig. 2) for connecting one wire through to bell and battery, the other wire from
mercury tube being soldered or fastened by a screw to instrument or fitting c, thus
leading to earth part of electric circuit being also connected to bell and battery.
In the shell casing is a slot hole for shewing upper portion of mercury tube
(see Fig. 1).
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is :-
1. The arrangement of a mercury tube with two wire ends of electric circuit
inserted and sealed into it out of contact with mercury therein at atmospheric
temperature for the purpose specified.
2. The combined general arrangement and construction of parts substantially of
instrument or fitting e as described and shewn in the accompanying drawings.
Dated this 3rd day of February 1894.
RICHARD BROWN.