An Improved Electric Low Water Alarm.
Year: 1892

page_text: Date of Application, 26th Jan., 1892-Accepted, 27th Feb., 1892
COMPLETE SPECIFICATION.
An Improved Electric Low Water Alarm.
I, STEPHEN MARTIN MATHEWS, of Rat Portage in the Province of Ontario,
and Dominion of Canada, Mechanical Engineer, 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 object of this invention is to provide an improved electric alarm which is
simple and durable in construction and especially designed for use on boilers to
give an aların at the time the water reaches the lowermost predetermined level.
The invention consists of a float controlled by the water in the boiler and
adapted to rest on and to press a spring for making an electric circuit.
The invention also consists of certain parts and details and combinations of the
same, as will be hereinafter fully described and pointed out in the claims.
Reference is to be had to the accompanying drawings, forming part of this
Specification, in which
Figure 1 is a sectional side elevation of the improvement as applied within the
boiler, and
Figure 2 is a similar view of the same as arranged on the outside of the boiler.
Similar letters of reference indicate corresponding parts in both figures.
The improved electric alarm is provided with a casing A preferably made in the
shape of a cylinder and arranged either in the boiler B, as shewn in Figure 1, or
on the outside thereof, as illustrated in Figure 2. In each case the casing A is in
communication with the water in the boiler so that the latter rises and falls in the
casing the same as in the boiler. Within the casing A is contained a ball C
floating in the water and rising and falling therewith. When the water reaches
the predetermined lowermost level the ball C rests on top of a spring D formed
with a contact point E at its free end and secured on an insulated plate F attached
to the bottom of the casing A. The spring D is connected with a wire G passing
through the insulated plate F and forming part of an electric circuit, the other
wire G belonging to the circuit also passing through the plate F and connecting
with the contact plate H secured on the plate with which the point E makes
contact when the spring D is pressed down by the weight of the ball C when the
water reaches a lowermost position within the boiler B and the casing A. The
wires G and G' are connected in the usual manner with a battery
or other
suitable source of electric supply and in the circuit of the wires is arranged an
alarm J of any approved construction. The spring D in its normal position has its
contact point E out of contact with the plate H, as plainly illustrated in Figures 1
and 2. Thus, on the water in the boiler B falling to a lowermost or dangerous
water level the ball C will rest on and depress the spring D so as to bring the free
end carrying the contact point E into contact with the plate H whereby an electric
circuit is established in the wires G and G¹ and the alarm J is sounded.
When the device is arranged on the inside of the boiler, as illustrated in
Figure 1, the casing A is supported by suitable brackets or other means in the
water, the brackets being attached to the tubes or flues, as shewn. On top of the
casing is arranged a guard to prevent the ball C from floating out of the casing A
when the water rises in the boiler.
In Figure 2 the casing A is shewn as connected by pipes with the interior of the
boiler similarly to a water gauge.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is;
1. An electric alarm comprising a float controlled by the water in the boiler, a
spring adapted to be pressed on by the said float, and an electric circuit adapted to
be closed by the said spring, substantially as shewn and described.
2. An electric alarm for boilers, comprising a casing connected with the interior
of the boiler, a float rising and falling with the water in said casing, a spring held
in the said casing and adapted to be pressed by the said float into contact with a
contact plate, and an electric circuit connecting with the said spring and said
contact plate and containing an alarm, substantially as shewn and described.
3. In an electric alarm, the combination, with the casing in communication with
the water compartment of the boiler, of a ball float arranged in the said casing and
controlled by the water therein, an insulated plate held in the bottom of the said
casing, a spring attached to the said insulated plate and adapted to be pressed by
the said float into contact with a contact plate held on top of the insulated plate
by means of a contact point on the said spring, and electric wires passing through
the said insulated plate and connecting with the said spring and the said contact
plate, substantially as shewn and described.
4. In an electric alarm, the combination, with a casing in communication with
the water compartment of the boiler, of a ball float arranged in the said casing and
controlled by the water therein, an insulated plate held in the bottom of the said
casing, a spring attached to the said insulated plate and adapted to be pressed on
by the said float, a contact plate held on top of the insulated plate and adapted to
be engaged by a contact point on the said spring and electric wires passing through
the said insulated plate and connecting with the said spring and the said contact
plate, and an alarm arranged in the circuit of said wires, substantially as shewn
and described.
Dated this 26th day of Janu 1800
S. M. MATHEWS,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.