IMPROVED MEANS OR APPARATUS FOR PREVENTING AND REMOVING INCRUSTATION AND
Year: 1882

page_text: LETTERS PATENT to Edward Field, of Chandos Chambers, Adelphi, in the
City of Westminster, Consulting Engineer, and William Lawson Thompson,
of 25 Old Jewry in the City of London for an Invention of IMPROVED
MEANS OR APPARATUS FOR
PREVENTING AND REMOVING INCRUSTATION AND
PROVISIONAL SPECIFICATION left by the said Edward Field and William
Lawson Thompson at the Office of the Commissioners of Patents on the
24th June 1882.
EDWARD FIELD, of Chandos Chambers, Adelphi in the City of Westminster,
Consulting Engineer, and WILLIAM LAWSON THOMPSON, of 25 Old Jewry in the
City of London IMPROVED MEANS OR APPARATUS FOR PREVENTING AND
"
REMOVING INCRUSTATION AND OPERATING A LOW WATER ALARM OR INDICATOR
IN STEAM BOILERS"
Our Invention has for its object improved means or apparatus for preventing
and removing incrustation and operating a low water alarm or indicator in steam
boilers and has reference to causing a current or currents of electricity to pass from
the shell or body of the boiler to a negative electrode situated in the water and
insulated from metallic contact with the shell or body of the boiler. So long as the
level of the water does not fall below a determined point when this level no longer
obtains the current, or a part of it, operates a signal or signals which may be audible
or visual or both.
To this end we provide a magneto,-electro, electro-magnetic or dynamo electric
generator and pass a conductor in connection with its negative pole (that is the
pole which corresponds to the zinc plate in an ordinary voltaic cell) through the
shell or body of the boiler in such a way that it is electrically insulated therefrom-
This conductor, which terminates in or acts as an electrode is so arranged that it is
normally in connection with the water in the boiler and we combine with it means
[Price l

page_text: operating by friction to keep it or a part of it clean and bright so that it may make
good electrical connection with the water.
Thus according to one arrangement to convey the electric current to the
water and keep the conducting surface or electrode bright, there is fixed to the
insulated negative conductor at or near the level of the low water line in
the boiler a metallic surface (or surfaces) and against this surface we cause another
surface to rub, its motion being derived from a float or other suitable contrivance
actuated by the motion of the water. Such float and rubbing or cleaning surface
are insulated from the boiler and from the negative conductor when not in contact
with the submerged clean surface. The float and rubbing surface are so arranged
that when the level of the water in the boiler falls below a determined point, the
rubbing piece shall not be in contact with the cleaned surface. Thus all electric
connection between the float and rubbing surface and the negative conductor or
electrode will be broken, and the electric current through the boiler will be
stopped; for the water will be below the cleaned surface of the negative conductor.
It is upon the rupture of the circuit through the water in the boiler that the
low water alarm or indicator is brought into operation. A convenient method of
indicating this is to cause the current to pass through the coils of an electro
magnet which attracts its armature so long as the current flows. When the
circuit is broken the armature will fall or be drawn away and the current
switched into any suitable signalling apparatus. Such apparatus may be a
trembling bell, or an electric lamp, or an electric motor that will open a steam or
water cock and extinguish the fire.
The electric generator employed may be of any suitable description and may be
used in conjunction with an accumulator or secondary battery if desired. In cases
where the prime mover does not run during the night, a secondary battery is
particularly serviceable as it keeps up the action during the time when there is
little or no circulation in the boiler a time that is specially favourable to the
settlement and hardening of scale.
It is also available for operating the low water alarm or indicator if the water
level descend during the night from leakage of steam or water or any other cause.
By this means the attention of the watchman or stoker is called to the danger.
In some cases our apparatus may with advantage be in connection with an
electric circuit provided for lighting or other purposes.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Edward Field and William Lawson Thompson in the Great Seal
Patent Office on the 23rd December 1882.
EDWARD FIELD of Chandos Chambers, Adelphi in the City of Westminster,
Consulting Engineer, and WILLIAM LAWSON THOMPSON late of 25 Old Jewry in the
City of London, now of York Buildings Adelphi in the City of Westminster.
IMPROVED MEANS OR APPARATUS FOR PREVENTING AND REMOVING INCRUSTATION
AND OPERATING A LOW WATER ALARM OR INDICATOR IN STEAM BOILERS.
Our Invention has for its object improved means or apparatus for preventing
and removing incrustation and also operating a low water alarm or indicator in
steam boilers, and has reference to causing a current or currents of electricity to
pass from the shell or body of the boiler, to a negative electrode situated in the
water so long as the level of the water does not fall below a predetermined point;
when this level no longer obtains the current or a part of it operates a signal' or
signals which may be audible or visible or both.
To this end we provide a magneto-electric or an electro-magnetic or a dynamo
electric generator, and we pass a conductor in connection with the negative pole
of the generator (that is the pole which corresponds to the zinc plate in an
ordinary voltaic cell) through the shell or body of the boiler in such a way that it
is electrically insulated therefrom. This conductor, which terminates in, or acts as,
an electrode, is so arranged that it is normally in connection with the water in the
boiler, and we combine with it means operating by friction to keep it, or a part
of it clean and bright, so that it may make good electrical connection with the
water.
Figs 1 and 2 of the accompanying Sheet of Drawings represent an arrangement
of apparatus according to our Invention. Fig 1 being a transverse section of a
boiler with our Invention applied to it, and Fig 2 a longitudinal section of the
same.
To convey the electric current to the water A and keep the conducting surface
or electrode bright, there is fixed to the insulated negative conductor C at or near
the level of the low water line in the boiler D a metallic surface (or surfaces) E
and against such surface or surfaces E we cause another surface or surfaces F to
rub, the motion of the latter being derived from some suitable contrivance such as
a float G actuated by the motion of the water.
The float G and rubbing or cleaning surfaces F are insulated (at the joint L)
from the boiler D and from the negative conductor C when not in contact with
the submerged clean surfaces E. The float G and rubbing surfaces F are SO
arranged that when the level of the water A in the boiler D falls below the pre-
determined point the rubbing piece F shall not be in contact with the cleaned
surfaces E. Thus all electrical connection between the rubbing surfaces of F and
the negative conductor or electrode C will be broken and the electric current
through the boiler (whose shell forms part of the circuit) will be stopped; for the
water will be below the cleaned surfaces of the negative conductor.
It is upon the rupture of the circuit through the water in the boiler that the low
water alarm or indicator is brought into operation.
A convenient method of indicating this is to cause the current to pass through
the coils of an electro magnet H which attracts its armature I so long as the
current flows
When the circuit is broken the armature I will fall or be drawn away and the
current will be "switched" into the signalling apparatus K, which may be of any
suitable construction, such as a trembling bell or an electric lamp, or an electric
motor that will open a steam or water cock and extinguish the fire.
In the drawing we have shown at rembling bell in conjunction with a plate on

page_text: the back of the armature, which plate bears the word "stopped" and assumes an
attitude in which it is plainly visible when the armature falls as it does when the
current through the boiler ceases.
The action of the apparatus is as follows:-In Figs 1 and 2 the float G with the
lever and rubbing surfaces F vibrate on the insulating joint L between the spring
pieces E which are fastened to the electrode C and carry or themselves constitute
the terminals to be kept clean. When the level of the water A falls sufficiently to
cause the rubbing surfaces F to clear the lower ends of the terminals E the water
will also leave them the electric circuit will be broken the armature I will then
fall thus displaying the word "stopped" (or any word or mark of similar signifi-
cation) and the current if not entirely stopped will be shunted through the
trembling bell apparatus or other means of signalling an alarm.
In Figs 3 and 4 are shewn similar views of so much as is needful to illustrato a
modification designed to produce the same effect.
The float G is electrically insulated at M from its lever which is not allowed to
touch the water and the rubbing arm or piece F is jointed in metallic contact with
the float lever and hangs loosely in the hook E at the end of the electrode C; the
rubbing piece F is free as the float rises or falls to move endwise backwards and
forwards so as by friction to keep both itself and the hook E Fig 3 clean and thus
when E is submerged to allow the electric current or currents to pass from the
water, through the insulator in the shell of the boiler, to the negative pole of the
electric generator.
The electric generator employed may be of any suitable description, and may be
used in conjunction with an accumulator or secondary battery if desired. In cases
where the prime mover does not run during the night, a secondary battery is
particularly serviceable, as it keeps up the action during the time when there is
little or no circulation in the boiler.
It will be noted that our apparatus serves to operate the low water alarm or
indicator in the event of the water level descending during the night either from
leakage of steam or water or from any other cause. Thus the attention of the
watchman or stoker is called to the danger.
In some cases our apparatus may with advantage be in connection with an electric
circuit provided for lighting or other purposes.
Having described the nature of our said Invention and the manner of carrying
it into practical effect what we claim as secured to us under the Letters Patent first
hereinbefore in part recited is :-
1. Providing a steam boiler with apparatus arranged in such a manner that so
long as the water in the boiler does not fall below a pre-determined level a current
(or currents) of electricity may be caused to pass from the shell or body of the
boiler to a negative electrode in the said water and that when such water falls
below the predetermined level, a signal (or signals) or indicator may be auto-
matically operated substantially as and for the purposes above set forth.
2. The use in conjunction with a steam boiler of the combined apparatus herein-
above described with reference to Figs 1 and 2 of the drawings (or modified as
described with reference to Figs 3 and 4) for the purposes set forth.
In Witness whereof I the said Edward Field have hereunto set my hand and
seal this twenty third day of December in the year of our Lord one
thousand eight hundred and eighty two.
EDWARD FIELD (LS.)