AN APPARATUS FOR CONTROLLING THE LOWEST HEIGHT OF WATER-LEVEL AND THE MAXIMUM TEMPERATURE IN STEAM-BOILERS BY THE MEDIUM OF ELECTRICITY
Year: 1881

page_text: LETTERS PATENT to Carl Pieper, Civil Engineer and Patent Agent, resident
at 109-110, Gneisenaustrasse, Berlin, S.W. Prussia, for an Invention of
"AN APPARATUS FOR CONTROLLING THE LOWEST HEIGHT OF WATER-LEVEL
AND THE MAXIMUM TEMPERATURE IN STEAM-BOILERS BY THE MEDIUM OF
ELECTRICITY." A communication- from Richard Schwartzkopff, of Berlin,
Prussia, Engineer.
PROVISIONAL SPECIFICATION left by the said Carl Pieper at the Office
of the Commissioners of Patents on the 5th May 1881.
CARL PIEPER, Civil Engineer and Patent Agent, resident at 109-110,
Gneisenaustrasse, Berlin, S.W. Prussia. 'AN APPARATUS FOR CONTROLING THE
LOWEST HEIGHT OF WATER-LEVEL AND THE MAXIMUM TEMPERATURE IN STEAM-
BOILERS BY THE MEDIUM OF ELECTRICITY." A communication from Richard
Schwartzkopff, of Berlin, Prussia, Engineer.
The subject matter of this Invention is an apparatus by means of which an
electric current is established for the purpose of giving a signal or of causing any
other suitable effect when the lowest admissible water-level or a certain maximum
temperature, resulting either from an excess of pressure or from retarded ebullition,
occurs in a steam-boiler, the electric contact being made by the melting of an
easily fusible metal.
The apparatus consists of two tubes, one inserted into the other with an annular
space between them. This space is closed at the top, whereas the inside tube,
which should project with its lower end from the outside tube, is closed at the
bottom. The outside tube is so fixed in the top of the boiler that its lower edge
is at the height of the lowest admissible. water-level. Its length outside of the
boiler is to be such that its upper end may remain comparatively cool.
Within the inside tube there are two insulated conducting wires or thin rods
which carry two cups or hollow disks of porcelain or other suitable insulating

page_text: material, one near the bottom of the tube and one near its top. The wires pass
through the upper cup and into the lower one. Between the cups and above the
upper cup they may be prevented from touching each other by being passed through
wooden or other non-conducting cylinders or plugs. The outer end of the wires
is connected with an electric battery and an electro-magnet which may be used
for operating a signalling device or an arrangement for extinguishing the fire or
dropping the grate-bars, &c.
On the edge of either of the said cups or disks a ring made of an easily fusible
metal is placed. The point of fusion of the lowering should be slightly higher
than the temperature which the water in the boiler has at the maximum degree
of steam-pressure allowed, whereas the upper ring must melt by the heat of the
steam when at its lowest pressure.
All parts being thus arranged and the water-level in the boiler being higher than
the lower edge of the outer tube, water will be pressed by the steam into the
annular space between the two tubes as far up as the air contained in this space
permits. The top end of the tubes maintained comparatively cool on account of
their length the upper fusible ring will remain unaltered, but when the water-level
sinks sufficiently steam will enter into the said annular space and by its heat melt
the ring, whereby electric contact between the wires is occasioned. When, on the
other hand, the steam-pressure and consequently the temperature of the water
becomes excessive, the lower ring will melt and cause electric contact.
The conducting wires or rods may be made in sections jointed or screwed together,
whereby their insertion into and withdrawal from the apparatus is under certain
circumstances facilitated.
Two or more controlling apparatuses may be connected with the same signalling
device, provided that in each conducting wire an electro-magnet be inserted,
arranged so as to cause the number of any controlling apparatus by which a current
has been established to appear on a register-board.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent. filed
by the said Carl Pieper in the Great Seal Patent Office on the 22nd
October 1881.
CARL PIEPER, Civil Engineer and Patent Agent, resident at 109/110,
Gneisenaustrasse, Berlin, S.W. Prussia. "AN APPARATUS FOR CONTROLLING THE
LOWEST HEIGHT OF WATER-LEVEL AND THE MAXIMUM TEMPERATURE IN STEAM-
BOILERS BY THE MEDIUM OF ELECTRICITY." (A communication from Richard
Schwartzkopff, of Berlin, Prussia, Engineer.)
The subject matter of this Invention consists in an apparatus by means of which
an electric current is established for the purpose of giving a signal or of causing
any other suitable effect when the lowest admissible water-level or a certain
maximum temperature, resulting either from an excess of pressure or from retarded
ebullition, occurs in a steam-boiler, the electric contact being made by the melting
of an easily fusible metal.
This apparatus is represented in two different arrangements on the annexed Sheet.
of Drawings.
Fig. 1 is a vertical section of the first arrangement; Fig. 2 shows a modification
of parts thereof.
Fig. 3 shows the upper portion of the second arrangement, and Fig. 3ª the
lower portion of the same, which is similar to the corresponding part of the first
arrangement.
The apparatus represented by Fig. 1 consists of two metal tubes e and fof
different diameter, the narrower tube e being inserted concentrically into the wider
tube f. Both tubes are so connected together at their upper end that the annular
space between them is hermetically closed at the top, whereas the inside tube e
which should project with its lower end from the outside tube f is closed at the
bottom. The tube fis fixed in such a manner in the crown of the boiler that its
lower edge is at the height of the lowest admissible water-level L.W. Its length
outside of the boiler must be such as to allow its upper end to remain comparatively
cool, four feet being ordinarily sufficient for this purpose.
Within the inside tube e there are two insulated conducting wires or thin
rods a, a, by preference of copper, which carry two cups or hollow disks b and b'
of porcelain or other suitable insulating material, the cup b being near the bottom
of the tube, and the cup b¹ near its top. Each of these cups is placed in a metal
ring somewhat longer than the cup, so as to form a projecting rim of the same.
The wires traverse the upper cup and pass into the lower one, which is fixed to.
their ends. For the purpose of preventing the wires from touching each other and
the tube e they are conducted through a cylinder d and a plug d made of wood or
other insulating material. Instead of this cylinder d a number of insulating disks.
such as shown in Figs. 3 and 3ª, together with a short plug d, may however be
applied. The outer end of the wires a, a, is connected by means of other wires,
with an electric battery and an electro-magnet, which may be used for operating
an alarm-bell or other signalling device, or an arrangement for extinguishing the
fire or dropping the grate-bars, &c.
Into the metal rings k, forming the rim of the cups or disks 6 and b¹, are placed
the rings c and respectively c¹ made of an easily fusible metal or alloy. The point
of fusion of the lower ring c should be slightly higher than the temperature which
the water in the boiler has at the maximum degree of steam-pressure allowed,
whereas the upper ring c¹ must melt by the heat of the steam when at its lowest
pressure. These rings are made to fit closely to the rim k in order to prevent their
outer surface from being oxydized. On the inside they may be similarly protected

page_text: by the end of the cylinder d and of the plug d¹. It is however not absolutely
necessary that the rings c and c¹ be constructed exactly as described. Their form
and arrangement may be modified, and even a fusible metallic body not being of
annular shape may be employed. Also the wires a, a, may be insulated in a
different manner.
The action of the apparatus is as follows:-
While the water-level in the boiler is higher than the lower edge of the tube f
water will be pressed by the steam into the annular space between the two tubes
as far up as the air contained in this space permits. The part of the apparatus
outside of the boiler being sufficiently long the surrounding air will keep the
temperature of its top end considerably below the temperature of the steam when
at its lowest degree of pressure. Under normal circumstances the upper ring c¹,
whose point of fusion may be, for instance, at 90 degr. centigrade (194° Fahr.,)
will therefore not melt. But when the water-level sinks below the lower edge of
the tube steam will enter into the annular space between c and f, and by its heat
melt the ring. The molten metal flows into the cavity 7 of the cup and produces
contact between the two wires a, a, whereby the electric apparatus is put into
operation.
When, on the other hand, the steam-pressure, and consequently the temperature
of the water, become excessive, the lower ring c will melt and cause the electric
contact between the wires a, a, in a similar manner, as in the first case.
same effect is produced by an excess of temperaturo caused by retarded
ebullition.
The
In order to prevent bubbles of steam from entering into the annular space
between the two tubes during the regular working of the boiler the projecting
part of the tube e may be provided with a collar m which directs these bubbles
sideward.
If the apparatus is to be used for controlling the height of water-level only the
cup b and the ring c are left away, but the tube e should not be made shorter, as
otherwise the water would fill out the whole area of the tube f, which might cause
a prejudicial heating of the upper part of the apparatus.
.
When a fusion of either of the rings c or c¹ has taken place the wires, together
with the cups, &c, are withdrawn from the tube e the metal which had been melted
is removed from the cup and a new fusible ring is introduced.
The conducting wires or rods a, a, may be made in sections, jointed or screwed:
together, as shown in Fig. 2, whereby their insertion into and withdrawal from the
apparatus is facilitated when there is but little room above the boiler.
In the modified apparatus represented by Fig. 3 the tube f is divided into two
parts, the upper one of which is hermetically attached to the tube e at the top as
well as at the bottom, whereas the lower part is thus fixed at the top only. The
two parts off are put in communication with each other by a comparatively
narrow pipe l, which is bent spirally or in 'other suitable manner so as to allow a
certain lengtli to be condensed into a small space. This pipe presenting a con-
siderable cooling surface for the water, which enters into the same, admits a
reduction of the total length of the apparatus outside of the boiler.
'
When in any works two or more boilers are provided with the controlling-"
apparatus, all these apparatuses may be put in relation with the same alarm-bell,
provided that a small electro-magnet be inserted into each circuit previous to its
connection with the other conducting-wires, the power of this electro-magnet being
utilized for indicating the number or other designation of the controlling-apparatus
by which the current has been established. As in other arrangements of this kind
the electro-magnet may for instance be employed for opening a hinged plate
which covers the number, &c., arranged together with the other numbers on a
register-board.
'
The described apparatus presents the advantage that it is not subject to such
inconveniences as often occur with the safety-apparatuses at present applied to
steam-boilers. It is not liable to become inoperative or to stick, as is often the

page_text: case with steam-gauges, floats, and safety-valves; its fusible rings are not exposed
to incrustation as the ordinary fusible plugs, and its action does not give rise to
any escape of steam. It is on the contrary always in a state to indicate with
certainty and in due time, all causes of danger of an explosion, including the
retarded ebullition, for the indication of which no appropriate instrument has
heretofore been in existance.
Having thus described the nature and object of this Invention, and the manner
in which it is to be carried out in practice as communicated to me by my
correspondent, I hereby claim as new and important features of the same,-
.
1. The combination with the two concentric tubes e and f connected together at
the top of an insulating cup b' placed in the upper part of the tube e of the con-
ducting-wires a, a, passing into the cup and connected with an electric alarm-bell
or other electric-receiver, and of an easily fusible metallic ring or body c', the parts
being arranged and combined substantially as herein before described and for the
purpose specified.
2. The combination with the tubes e and f, the insulating cup.61, the conducting-
wires a, a, connected with an electric alarm-bell or other electric receiver,.and the
ring or body c¹ of the insulating cup placed in the lower part of the tube e,
and carrying the easily fusible metallic ring or body c, the wires a, a, passing into
or through the cup b₁ and into the cup 6, substantially as and for the purpose
specified.
3. The combination with the tube e containing the cups b and b, the conducting-
wires a, a, and the fusible metallic rings or bodies c and c', and with the tube f
made of two parts, of the pipe l, as hereinbefore described and for the purpose
specified.
·
4. The combination with the tube e surrounded by the tube f, and containing
the described parts a, a, b, b', and c¹ of the collar m as and for the purpose
stated.
In witness whereof, I have hereunto set my hand and seal, this Eighteenth
day of October, in the year of our Lord One thousand eight hundred
and nighter and
CARL PIEPER. (L.S.)