IMPROVEMENTS IN APPARATUS FOR REGULATING THE DRAFT IN STEAM BOILER FLUES, FOR REGULATING THE PASSAGE OF STEAM OR COMPRESSED AIR THROUGH PIPES
Year: 1879

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in
the County of Middlesex, Gentleman, for the Invention of "IMPROVEMENTS
IN APPARATUS FOR REGULATING THE DRAFT IN STEAM BOILER FLUES,
FOR REGULATING THE PASSAGE OF STEAM OR COMPRESSED AIR
THROUGH PIPES." A communication from abroad by Alfred Craven Harrison,
of Philadelphia, Pennsylvania, United States of America.
AND
1
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 17th April 1879.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN APPARATUS FOR REGULATING THE DRAFT IN
STEAM BOILER FLUES, AND FOR REGULATING THE PASSAGE OF STEAM OR COM-
PRESSED AIR THROUGH PIPES." A communication from abroad by Alfred Craven
Harrison, of Philadelphia, Pennsylvania, United States of America.
The main object of this Invention is to so regulate the damper of a steam boiler
flue by the pressure of steam through the medium of devices hereinafter described
that the evils resulting from the repeated entire closing of the damper by the
automatic appliances now in use for the purpose may be obviated.
The Invention may also be applied to other uses hereinafter referred to.
Apparatus for regulating dampers for steam boiler flues by intermittent move-
ments have been constructed in the following manner, viz. :-
An elastic diaphragm is fitted within an outer casing so that steam from the
boiler shall act through the medium of this diaphragm a suitable block or piston
above the same, and a rod on a weighted lever which is pivotted to the casing, the
outer end of the lever being connected to a damper in the flue of a boiler by such
a system of rods, levers, and other appliances, as the character of the damper and
its location in respect to the lever may suggest.
In applying the Invention to this class of instruments a plate is erected above
the weighted lever, from which plate is suspended any desired number of weights
by rods which above the plate are furnished with thumb screws, and below are
forked so as to straddle the lever. The suspension rods and their weights are so

page_text: adjusted by the thumb screws that the lever when it rises under the pressure of
steam will, after reaching a given altitude, be loaded by one weight, and after
overcoming this load and rising to a further height will receive another load, a
third load being added after the lever reaches a still higher altitude. When there
is a slight excess of pressure of steam in the boiler the lever instead of being raised
to a sufficient extent to entirely close the damper as in previous devices of this
class will be arrested in its upward movement by one of the weights which gives
the lever an additional load to carry, and to oppose the excess of pressure, the
damper being closed to the limited extent determined by this additional load.
Should the pressure of steam in the boiler be reduced and resume its normal con-
dition the lever will fall to its original position, the weight will remain suspended
clear of the lever, and the damper will be entirely open. If, on the other hand,
there should be such an excess of pressure of steam as to raise the lever loaded by
the first weight it will after rising a short distance be further loaded with a second
weight, and there will be a further contraction of the flue by the damper, a still
further rise of the lever resulting in the arresting of the latter by a third load, and
in a further contraction of the flue.
It will be seen that the lever and damper do not move uniformly and simul-
taneously with the increase or diminution of the excess of pressure of steam, but
intermittently, that is to say, the lever and damper move under a given excess of
pressure until the lever receives its first load, and both remain quiescent until the
steam assumes its normal pressure or until the excess of pressure is so great that it
will overcome the first load and be arrested by the second, or until the first and
second loads are raised by the lever, and the latter is arrested by the third load,
but this intermittent action of the damper serves to bring about the desired result,
that is, such a control of the combustion of fuel by the damper that the above
described evil effects cannot take place.
A succession of loads can be applied to the lever in different ways, for example,
there may be a series of weights arranged one within the other, and supported by
any fixed object, a rod suspended from the lever passing through the whole of the
weights, and being provided within the smallest weight with a nut. The lever in
this case also must rise a short distance before it comes under the control of the
first weight, a further distance before it is loaded with the second weight, and a
still further distance before it comes under the influence of the third weight.
The above described regulating device has been assumed as applied in connection
with a damper in the flue of a steam boiler furnace, but it may be connected to
the throttle valve of a steam pipe, or to both the throttle valve and damper. A
piston operating in a cylinder may also be substituted for a diaphragm in a casing,
and the lever as it rises may be resisted by a succession of loads consisting of a
series of properly adjusted and properly regulated springs in a manner which will
readily suggest itself to skilled engineers.
According to another modification the load on the lever as it rises is caused to
increase gradually instead of intermittently. In this case a bell crank lever is
hung to the main lever, the long arm of the bell crank lever carrying a weight, and
the short arm bearing against the underside of a fixed pin, or the short arm may
be connected by a link to a fixed pin. When there is an excess of pressure of
steam in the boiler the diaphragm in the casing, and consequently the lever will
rise but only to an extent commensurate with the excess of pressure, for as the
lever rises the weight will also be elevated, the lever will be virtually lengthened,
and the load on the diaphragm will be increased until it is sufficient to resist the
actual excess of pressure when the upward movement of the lever will cease, the
damper being closed to an extent demanded and determined by the excess of pres-
sure of steam. Simultaneously with the gradual resumption by the steam of the
desired normal pressure the lever will gradually fall, and there will be a gradual
diminution of the load on the diaphragm.
According to a further modification the weight is caused to slide by means of
arms secured to a pin which is adapted to bearings in projections on the casing, &

page_text: short forked arm secured to the pin fitting between the collars on the rod. As the
lever gradually rises under an excess of pressure of steam the weight will be
caused to slide or move outwards on the said lever, and the load on the same will
be gradually increased.
According to another plan of automatically imparting a differential load to the
lever the sliding weight is connected by a link or links to any fixed object.
A gradually increasing load may also be imparted to the lever as it rises by
connecting the rod of the diaphragm to a pin on the casing by means of a link
or links; as the diaphragm in the casing rises the upper end of the rod, which may
be provided with a roller, must be drawn towards the fulcrum, and consequently
the leverage or load to resist the pressure must increase as the pressure on the
diaphragm increases.
The rod of the diaphragm or piston may be connected directly to a damper or
throttle valve without the intervention of a lever, providing the upward move-
ment of the rod is arrested by a succession of loads, such for example as
weighted levers. If the lowest lever is not sufficient to resist the excess of
pressure of steam it will rise until an adjustable projection on the said lever
reaches the second lever, and if the latter yields, its adjustable projection will
reach the third or uppermost lever with results similar to those described
above.
A system of springs may be used as a succession of loads, or the rod may
act directly on a succession of weights.
Although in the foregoing description an elastic diaphragm exposed to the
action of the steam in the boiler has been referred to, the Invention is not restricted
to a diaphragin, as one of the parts which constitutes the Invention, as for
example, a cylinder with a piston which will yield to the pressure of steam, may
be used, and although the Invention has been referred to as applied to the
regulating of dampers, it may, as before remarked, be connected with the throttle
valve in a steam pipe, or with both throttle valve and damper, or it may be used
in connection with blowing apparatus to regulate the volume of compressed air
forced through a pipe.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by.
the said John Henry Johnson in the Great Seal Patent Office on the 6th
October 1879.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields,, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN APPARATUS FOR REGULATING THE DRAFT IN
STEAM BOILER FLUES, AND FOR REGULATING THE PASSAGE OF STEAM OR COM-
PRESSED AIR THROUGH PIPES." A communication from abroad by Alfred Cravon
Harrison, of Philadelphia, Pennsylvania, United States of America.
The main object of the said Invention is to so regulate the damper of a steam
boiler flue by the pressure of steam through the medium of devices hereinafter
described, that the evils resulting from the repeated entire closing of the damper by
the automatic appliances now in use for the purpose may be obviated.
The Invention may also be applied to other uses hereinafter referred to.
And in order that the said Invention may be fully understood, I shall now
proceed more particularly to describe the same, and for that purpose shall refer to
the several Figures on the annexed Sheet of Drawings, the same letters of reference
indicating corresponding parts in all the corresponding Figures.
Figure 1 of the accompanying Drawings is a perspective view illustrating the
application of the Invention to the regulating of dampers of steam boiler flues by
intermittent movements.
Figure 2 represents a modification of Figure 1.
Figure 3 is a section of part of Figure 1 drawn to a larger scale.
Figures 4, 5, and 6 show a plan of carrying out the Invention in which there is a
gradual instead of a differential load on a lever in accordance with a differential.
pressure of the excess of steam in the boiler.
•
Figures 7, 8, 9, and 10 are modifications of Figures 4, 5, and 6, and Figure 11,
another modification of the Invention.
In Figures 1 and 3, A is a casing containing an elastic diaphragm, steam from
the boiler acting through the medium of this diaphragm a suitable block or piston
above the same, and a rod a on a weighted lever E which is pivotted to the
casing A, the outer end of the lever being connected to a damper B in the flue
of a boiler by such a system of rods, levers, and other appliances as the character
of the damper and its location in respect to the lever may suggest.
This is a well known device in common use for causing the pressure of steam
to operate a damper in the flue of a steam boiler.
There is one defect in this otherwise useful instrument, and that is, its tendency
to entirely close the damper whether the excess of pressure of steam in the boiler
be great or small, hence the operation of the damper is not in accordance with
the degree of pressure which exceeds the desired normal pressure of steam in the
boiler, and the consequence of this is that the damper is frequently closed when
a slight excess in the pressure of steam occurs, and when it should be partly
open.
It is well known to engineers that to cut off or nearly cut off the draft in a boiler
flue at intervals is to interfere with the economical consumption of fuel, for while
the beat beneath the boiler is diminished as long as the damper remains closed a
portion of the fuel is converted into ashes and clinkers, owing to the heat which is
confined to the fire-place, so that when the flue is again opened time must elapse
before the burning fuel can resume its proper combustion, the services of the fireman
being moreover required in clearing away the ashes and clinkers.
In applying the present Invention to this class of instruments a plate G is
erected above the weighted lever E, Figure 1, and from this plate is suspended any
desired number of weights a¹, a³, a³, by rods m, which above the plate are furnished
with thumb screws, and below are forked so as to straddle the lever E.

page_text: The suspension rods and their weights are so adjusted by the thumb screws that
the lever when it rises under the pressure of steam will after reaching a given
altitude be loaded by one weight, and after overcoming this load and rising to a
further height will receive another load, a third load being added after the lever
reaches a still higher altitude.
When there is a slight excess of pressure of steam in the boiler, the lever instead
of being raised to a sufficient extent to entirely close the damper, as in previous.
devices of this class, will be arrested in its upward movement by one of the weights,
which gives the lever an additional load to carry and to oppose the excess of
pressure, the damper being closed to the limited extent determined by this
additional load.
Should the pressure of steam in the boiler be reduced and resume its normal
condition, the lever will fall to its original position, the weight will remain
suspended clear of the lever, and the damper will be entirely open.
If on the other
hand there should be such an excess of pressure of steam as to raise the lever
loaded by the first weight, it will after rising a short distance be further loaded
with a second weight, and there will be a further contraction of the flue by the
damper, a still further rise of the lever resulting in the arresting of the latter by a
third load, and in a further contraction of the flue.
It will be seen that the lever and damper do not move uniformly and simul-
taneously with the increase or diminution of the excess of pressure of steam but
intermittently, that is to say, the lever and damper move under a given excess of
pressure until the lever receives its first load, and both remain quiescent until the
steam assumes its normal pressure, or until the excess of pressure is so great that it
will overcome the first load and be arrested by the second; or until the first and
second loads are raised by the lever and the latter is arrested by the third load;
but this intermittent action of the damper serves to bring about the desired result,
that is, such a control of the combustion of fuel by the damper that the above
described evil effects cannot take place.
It has been found that good results may be obtained by a single supplementary
load, but in practice it is best to use at least three weights to be brought into
action successively in the manner and under the circumstances above described.
A succession of loads can be applied to the lever in different ways, for example,
there may be a series of weights m, m', m³, arranged one within the other, as
shewn in Figure 2, and supported by any fixed object, a rod suspended from the
lever passing through the whole of the weights, and being provided within the
smallest weight with a nut.
The lever in this case also must rise a short distance before it comes under the
control of the first weight, a further distance before it is loaded with the second
weight, and a still further distance before it comes under the influence of the third
weight.
In Figure 1 the lever is loaded with weights w, w, independently of the supple-
mentary weights a¹, a², a³, but it will be evident that the latter may be of such
dimensions and so arranged that the said weights w, w, may be dispensed with.
It will also be evident that the Invention is not restricted to any specific kind of
damper.
The above described regulating device may be connected to the throttle valve of
a steam pipe or to both the throttle valve and damper.
The lever as it rises may be resisted by a succession of loads, consisting of a series
of properly adjusted and properly regulated springs, in a manner which will readily
suggest itself to skilled engineers.
In the plan shown in Figures 4, 5, and 6 there is a gradual instead of intermittent
increase of the load on the lever E as it rises. In this case a bell-crank lever G is
bung to the main lever E, the long arm of the bell crank lever carrying a weight w¹,
and the short arm bearing against the underside of the fixed pin c, Figures 4 and 5;
or the short arm may be connected by the link y, shown in Figure 6, to a fixed
pin z

page_text: When there is an excess of pressure of steam in the boiler, the diaphragm in the
casing A, and consequently the lever E, will rise, but only to an extent com-
mensurate with the excess of pressure, for as the level rises the weight w' will also
be elevated, the lever E will be virtually lengthened, and the load on the diaphragm
will be increased until it is sufficient to resist the actual excess of pressure, when
the upward movement of the lever will cease, the damper being closed to an extent
demanded and determined by the excess of pressure of steam.
Simultaneously with the gradual resumption by the steam of the desired normal
pressure the lever E will gradually fall, and there will be a gradual diminution of
the load on the diaphragm.
In Figures 7 and 8, arms n, n¹, connected to a sliding weight on the lever are
Becured to a pin p, which is adapted to bearings in projections h on the casing A, a
short forked arm g secured to the pin fitting between collars on the rod a.
As the lever gradually rises under an excess of pressure of steam the weight will
be moved outwards on the said lever, and the load on the same will be gradually
increased.
Another plan of automatically imparting a differential load to the lever is shown
in Figure 9, where the sliding weight is connected by a link or links to any fixed
object.
A gradually increasing load may also be imparted to the lever as it rises by con-
necting the rod a to a pin on the casing A by means of a link or links 8, as shown
in Figure 10.
As the diaphragm in the casing rises the upper end of the rod, which may be
provided with a roller, will be drawn towards the pivot u, and consequently the
leverage or load must increase as the pressure on the diaphragm increases.
The rod a of the diaphragm or piston may be connected directly to a damper or
throttle valve without the intervention of a lever, providing the upward move-
ment of the rod is arrested by a succession of loads, as in the arrangement
shewn in Figure 11, in which the loads consist of three weighted levers W, W¹,
and W
If the lowest lever is not sufficient to resist the excess of pressure of steam it
will rise until an adjustable projection 8 on the said lever reaches the second lever,
and if the latter yields its adjustable projection will reach the third or uppermost
lever, with results similar to those described above.
A system of springs may in this case also be used as a succession of loads, or the
rod a may act directly on a succession of weights.
Although in the foregoing description an elastic diaphragm exposed to the action
of the steam in the boiler has been referred to, the Invention is not restricted to a
diaphragm as one of the parts which constitutes the Invention, as, for example, a
cylinder with a piston which will yield to the pressure of steam may be used; and
although the Invention has been referred to as applied to the regulating of dampers,
it may, as before remarked, be connected with a throttle valve in a steam pipe, or
with both throttle valve and damper; or it may be used in connection with
blowing apparatus to regulate the volume of compressed air forced through a pipe.
Having now described and particularly ascertained the nature of the said In-
vention, and the manner in which the same is or may be used or carried into effect,
I would observe in conclusion that what I consider novel and original, and
therefore claim as the Invention secured to me by the herein before in part recited
Letters Patent is,-
First. A regulating device, in which a diaphragm or piston exposed to pressure
is combined with a damper or throttle valve or their equivalents, and with weights
or equivalent loads which will resist in succession the said diaphragm or piston as
it rises under an excess of pressure, and from which the piston or diaphragm will
be relieved in succession as the excess of pressure is reduced, all substantially as
herein before described.
Second. The combination of the diaphragm or piston, a lever connected to a
damper or throttle valve or their equivalents, and a series of weights by which the

page_text: said lever is loaded in succession as it rises, all substantially as herein before
described.
Third. The combination of a diaphragm or piston and lever with a moveable
weight and with devices substantially as described, whereby the said weight is
caused to move outward from the fulcrum of the said lever as the latter rises under
an excess of pressure, substantially as herein before described.
Fourth. The combination of a diaphragm or piston, weighted lever, and the rod
through which the said diaphragm or piston acts on the lever, with a device by
which the said rod is caused to move nearer to the pivot of the lever as the latter
rises.
In witness whereof, I, the said John Henry Johnson, have to this my Specifi-
cation set my hand and seal, the Sixth day of October, One thousand eight
hundred and seventy nine.
J. HENRY JOHNSON. (L.S.)