Year: 1899

page_text: Date of Application, 22nd Dec., 1899-Accepted, 24th Mar.,
1900
I, STEPHEN MARTIN MATHEWS, of No. 133, West 43rd Street, in the City & State
of New York, United States of America, Engineer, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be particu-
larly described and ascertained in and by the following statement:-
This invention relates to certain new and useful improvements in electric alarms
for steam generating boilers, and it relates more particularly to its peculiar
construction and arrangement and its relative position to the water-line of the
boiler, the object of the invention being to so arrange the apparatus that it will
instantaneously sound an alarm when the water in the boiler has fallen below a
predetermined level; and the invention consists essentially in providing the
try-cock with an expansion-chamber in communication with either the water-
column of the boiler or with the boiler itself, an hermetically-sealed air-chamber
contiguous to the expansion-chamber, a diaphragm actuated by the air within the
hermetically-sealed air-chamber, and an adjustable contact-screw in circuit with
the battery and alarm, through which the circuit is completed when the air in the
hermetically-sealed chamber is expanded to move the diaphragm into contact
with the point of the contact-screw; as hereinafter more fully set forth and more
particularly pointed out in the claims.
In the drawings:
Figure 1 is a sectional view of the apparatus.
Figure 2 is an enlarged sectional view of the upper part of the apparatus,
showing the air-chamber, diaphragm and contact-screw.
Figure 3 is a plan view of the top of the same.
A represents the shell of the apparatus, one end of which is provided with an
integrally formed concavo-convex enda and the other end of which is provided
with a screw-threaded stem a to be fitted into the boiler or water-column.
B represents a chamber within the shell A, and represents an opening
through the stem a', communicating with the chamber B.
O represents the drain-cock communicating with the chamber B contiguous
to the inner side of the end a. The stem when the apparatus is in position is
fitted into the water-column or boiler and the water or steam passes from the
boiler or water-column through the opening of the stem into the
chamber B. By means of the drain-cock the contents of the chamber B can
be permitted to escape by opening its valve.
The end of the shell A is provided with a dome S between which and the con-
caved end of the shell is formed an air chamber. Located centrally between the
dome and the concaved end of the shell is a diaphragm 1) the side face of which
is opposed to the concaved end a and which is made of electrically-conducting
metal.
H represents a post provided with a screw-threaded stem h fitted through the

page_text: top of the dome S, and interposed between the screw-threaded stem h and the
dome S is an insulated washer G to prevent electrical contact between the post and
the dome. Passing through the post H is an adjustable contact-screw J provided
with a lock-nut I adapted to bear against the top of the post, the lower end of
which is adapted to be engaged by the diaphragm 1 when actuated by the expan-
sion of the air in the chamber C formed between the diaphragm and the concaved
end of the shell.
Formed through the shell A into the chamber C is an opening fitted with a
screw N by means of which the air can be admitted to the chamber. In order
to provide a means of access to the chamber T and the diaphragm through the
dome, the dome is provided with an enlarged opening fitted with a nut R the
shank of which is screwed into the opening and which is provided with a central
bore to receive the insulated washer G through which passes the stem of the
post H the inner end of the post being locked to the washer by means of a nut,
and the outer part of which is provided with a shoulder resting against the outer
part of the washer.
The post H is provided with an extension L to receive the circuit-wire, and
the extension L is provided with a set screw for locking the wire to the
extension L.
The use of the invention is as follows: The stem a' of the shell A is screwed
into the boiler or water-column slightly below the water line. When the water
in the boiler or water-column is at its normal level, that is, at the level of the
water line, it will pass through the opening in the stem a to the chamber B
and prevent the passage of the steam from the boiler to the chamber. The
contact screw is adjusted so that it will not engage the diaphragm until the tem-
perature in the chamber B has risen above 212 degrees Fahrenheit, which is
the sensible temperature of boiling water. When the water in the boiler or
water-column has fallen below the water line the water will drain from the
chamber B back into the boiler or water-column and allow of the passage of the
steam from the boiler or water-column into the chamber B, and as the steam is
always under pressure in a generating boiler it will increase the temperature of
the chamber above 212 degrees, raising the temperature of the air in the closed
chamber C to the same temperature, and cause the movement of the diaphragm
towards the point of the contact screw, grounding the current by means of the
contact screw and the remaining parts of the apparatus, completing the circuit
of the current through the wire F to the electric bell in any ordinary manner.
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. An electric alarm try-cock, consisting of an expansion-chamber communi-
cating with the water-column or boiler, a concavo-convex end for the expansion
chamber, a diaphragm opposed to the concavo-convex end, adapted to form
between itself and the said end of the chamber an hermetically-sealed air-chamber,
a supplemental end for the expansion-chamber, enclosing the diaphragm, an
insulated post passing through the supplemental end, a contact-screw passing
through the post, and the point of which is adapted to be engaged by the
diaphragm when actuated by the expansion of the air within the hermetically-
sealed air-chamber to complete the circuit to the alarm, substantially as specified.
2. An electric alarm try-cock, consisting of an expansion-chamber communi-
cating with the water-column or boiler, a concavo-convex end for the expansion
chamber, a diaphragm opposed to the concavo-convex end, adapted to form
between itself and the said end of the chamber an hermetically-sealed air-chamber.
a supplemental end for the expansion-chamber, enclosing the diaphragm, an
insulated post passing through the supplemental end, a contact-screw passing
through the post in circuit with the alarm, the point of which is adapted to be
engaged by the diaphragm when actuated by the expansion of the air within the

page_text: hermetically sealed air-chamber, which is provided with an opening between the
diaphragm and supplemental end to allow of the escape of the air from within it,
substantially as specified.
20
D
1000
SYDNEY E. PAGE,
28, New Bridge Street, London, E.C., Agent for the Applicant.