or Pressure Alarm for Boilers.
Year: 1886

page_text: or Pressure Alarm for Boilers.
We CLEMENT BONNENBERG and MAX KOYEMANN, both of Düsseldorf' in the
German Empire, Engineers, in firm of Bonnenberg & Koyemann do hereby declare
the nature of our invention and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement :—
Our invention for a temperature alarm apparatus applicable also as a low water
or pressure alarm for boilers consists principally in the application of a membran,
that is to say a thin elastic plate, flexible to both sides which is moved by the
heating or cooling of a closed volume of air. The membran itself is connected
with an electric circuit and whenever it moves, it opens or closes the electric
current, by which means any change of temperature in the space in which the
controlling apparatus is placed is indicated at once. By the opening or closing
of the current an alarm (call) is made to function. The alarm can be applied
anywhere.
The apparatus consists materially in a vessel with thin sides and is closed off on
the one side by a metal-membran. This metal-membran stands in connection
with an electric source. In the casing of the apparatus and above the metal
membran is an adjusting screw, which can be brought nearer or farther to the
metal membran as may be desirable.
The adjusting screw is likewise in connection with the electric source.
Whenever the volume of air contained in the closed space begins to expand in
consequence of a rise in the temperature, the membran gives way and at a certain
pressure, which is equivalent to a certain temperature of the closed volume of air,
the metal membran touches the adjusting screw. By this means the electric
current, which is connected with both these mechanisms, is shut and sets an
alarm in motion and keeps it going until the temperature is lowered and the
electric current is broken by the relaxing pressure. The alarm is set in motion by
the electric current in the well known way and can be applied anywhere.
In the drawing the apparatus is represented in several modifications and in
several methods for using it. This apparatus can be used on steam-boilers and in
factories etc. and serves as an alarm whenever the temperature gets too high.

page_text: °
Fig. II shows a side-view of an apparatus which operates as an alarm when the
water is below its proper level.
Fig. III represents a vertical section of an apparatus which serves to indicate
the highest temperatures. It is fixed in some place of a space, in which it is
exposed to the greatest heat and it will then indicate the highest temperature in
that space and make alarm.
Fig. IV illustrates a modification of the apparatus shown in fig. III; it answers
the same purpose as the apparatus represented in fig. III.
Fig. V shows a view of the apparatus seen from above.
The apparatus shown in fig. I is applied to the steam-boiler for which it is.
intended in such a way that tuber reaches to the lowest level the water is allowed
to have. The apparatus itself is fastened hermetically to the boiler, and is com-
posed of the tube r, the casing g and another tube r³, which is shut off on top by
a cover d. This cover d bears the apparatus in the following way:
The cover d which is fastened air-proof on to tube 1 by means of screw-threads
and nuts, bears the membran b which is secured by a coupling-box m² to cover d.
A conducting-wire leads the current through screws which is encircled by the
insulating-plate i to the coupling-box m¹ and from the latter through cover d to
the membran b.
The second conducting-wire l¹ of the electric-current is led to the coupling-box f
and is therefore in connection with the adjusting-screw a, made to screw up and
down in this coupling-box..
The cover d bears the cup c which extends into the tube r¹ and which must
have as large an upper surface as possible (in order to obtain a quick effect of the
temperature by means of the volume of water or steam contained in tube r¹) so
that the temperature of the volume of water or steam contained in tube ¹ takes
effect as quickly as possible.
The way in which this apparatus works is as follows:
As long as the water in the steam-boiler x covers the lower outlet of tube.r the
whole apparatus just described is full of water. When the water-level falls, the
steam from the steam-boiler enters r¹ and plays round cup c.
до
The steam heats
the latter more than the boiler-water does and consequently the tension in c rises
and causes the membran 6 to move upwards. In ascending it touches the adjusting-
screw a and the electric current is closed at once. The well-known electric alarm
is set in motion and indicates a want of water in the boiler.
In order to prevent over-tension of the membran b, when the temperature
fluctuates too much support-plates can be applied both above and below the
membran. These support-plates protect the membran 6 from bending through too
much in case cup c gets overheated or cools too much. In fig. I may be seen under
membran b a grate t that answers the same purpose.
A side-apparatus p is also applied in fig. I. It is of the same construction as the
chief apparatus and operates in the same way; but as the tubes ³ are not in
connection with the water of the boiler but with the steam-space, it serves to give
the alarni when the pressure is too high. The steam operates therefore continually
on this side-apparatus and its adjusting-screw a, applied in the same way as in the
chief apparatus, is set at such a point that the electric current is not closed and
consequently the alarm is not set in motion, until the temperature rises owing to
an excess of steam-pressure.
This auxiliary apparatus therefore serves to indicate when the momentary
steam-pressure is above the allowed limit.
In fig. II the present improvement is applied direct to the glass of the water-
gauge. W is the water-gauge into which projects the vessel c', corresponding with
vessel c of fig. I. It works as follows: as long as the water plays round vessel c¹
the temperature of the latter and the tension in it do not suffice to effect a closing
of the electric current; the current is not closed until steam plays round vessel c.
Figs. III & IV illustrate particular parts of the apparatus and show two modifi-
cations of the latter. In fig. III the electric current is broken at a low temperature

page_text: (exactly as in Fig. 1) and when the temperature rises above the highest point
allowable the electric current is closed.
As regards its construction and arrangement this. modification corresponds in all
points with fig. I, excepting that the disc n is made of a non-conducting material
for the purpose of insulating.
In fig. IV the electric current is constantly closed when the temperature is low;
the current runs in this case from wire l, screw xl to the membran b and on to
a metal pin q, fixed on to the latter. From there it passes on to the plate p¹ which
is made adjustable on pin q.
This plate p lies when the temperature is low against ring o and from the latter
the current reaches the wire l'.
It is evident that the electric current is constantly closed until the tension in
vessel c gets so high, that the membran 6 lifts plate p² from ring o. Then the
current is broken and the electric controlling apparatus being constructed in
such a manner that the alarm is set in motion when the current is broken, the
alarm will also in this case indicate that the temperature has risen above the
highest point allowed. These apparatus can also be used to indicate the lowest
temperature; both indicated in figs. IV & V can be used for this purpose.
If the electric controlling apparatus, which operates when the current is broken,
is applied to the apparatus represented in fig. IV and the adjusting-screw a is set '
in such a way that the membran falls and recedes from the adjusting-screw
whenever the temperature sinks below the lowest desirable point, the alarm will
indicate the sinking of the temperature below the lowest point allowed.
The effect is just the same if a controlling apparatus which is set in operation,
when the current is closed is applied to the apparatus shown in fig. V.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is
1.) The application of a closed cup c with a metal-membran b and a screw a
which can be set against membran b all of which are connected with the electric
current in such a way, that whenever membran b touches the screw or recedes
from it, the electric current is either closed or opened for the purpose as specified.
2.) The application of support-plates t to the apparatus. described in claim 1,
which are fixed above or below the membran, or both above and below, and serve
to protect it.