IMPROVEMENTS IN SURFACE CONDENSING ENGINES
Year: 1883

page_text: LETTERS PATENT to Joseph Chapman of Leith in the County of Midlothian
North Britain, Engineer, for an Invention of "IMPROVEMENTS IN SURFACE
CONDENSING ENGINES"
PROVISIONAL SPECIFICATION left by the said Joseph Chapman at the
Office of the Commissioners of Patents on the 9th January 1883.
JOSEPH CHAPMAN, of Leith, in the County of Midlothian, North Britain,
Engineer. "IMPROVEMENTS IN SURFACE CONDENSING ENGINES,"
This Invention which relates to Improvements in surface condensing engines
consists of an arrangement of pump, valves, and connections for creating and
maintaining a vacuum in the condenser. The pump is double acting, the part
thereof below the piston being the air pump and the part above the piston, the
feed pump. The action of the part of the pump below the piston is to draw off
the air and water from the condenser and forco it up a pipe, the air rising to a
receiver which may be the hot-well of the engine. From this receiver the air is
drawn off by the action of the circulating pump whilst the water is taken off by
the action of the upper part of the pump through valves and delivered to the
boilers-A pipe and stop-cock is also provided for use between the hot-well and
condenser in the event of the air pump failing to give to the condenser the hot-
well vacuum.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Joseph Chapman in the Great Seal Patent Office on the 7th July
1883.
JOSEPH CHAPMAN, of Leith, in the County of Midlothian, North Britain,
Engineer "IMPROVEMENTS IN SURFACE CONDENSING ENGINES"
My said Invention which relates to Improvements in surface condensing Engines
consists of an arrangement of pump, valves and connections for creating and
maintaining a vacuum in the condenser.-The pump is double acting, the part
thereof below the piston being the air pump and the part above the piston, the
feed pump. The action of the part of the pump below the piston is to draw off
the air and water from the condenser and force it up a pipe-the air rising to a
receiver which may be the hot-well of the engine.-From this receiver the air is
drawn off by the action of the circulating pump whilst the water is taken off by the
action of the upper part of the pump through valves and delivered to the boilers.→
A pipe and stop-cock are also provided for use between the hot-well and
condenser in the event of the air pump failing, to give to the condenser the
hot-well vacuum.
And in order that my said Invention may be properly understood, I now proceed
more particularly to set forth the system, mode or manner in or under which the
same is or may be used or practically carried into effect, reference being had to the
accompanying Drawings, and to the Letters and Figures marked thereon, that is
to say-
Figure 1, represents in part front elevation and part vertical section an arrange-
ment of mechanism constructed according to my present invention.
Figures 2, and 3, are respectively side elevation and plan of the same.
Figure 4, is a part transverse section of an air receiver used in the carrying out
of my Invention.
Figure 5, is a vertical section through a modified form of pump that may be
used in carrying out my Invention.
Figure 6, is a further modified form of pump that may be used in carrying out:
my present Invention.
In carrying my invention into practice the pump a, is constructed as a double
acting pump, that is to say, the part below the piston b, is used as the air pump
and the part above the piston b, as the feed pump. The action of the part of the
pump below the piston 6, in its up stroke is to draw off the air and water from the
condenser c, through the pipe d, and valve e, and in its down stroke to force
the air and water thus drawn from the condenser through the valve f, and up
the pipe g, the air rising to the receiver h, which may be the hot-well of the
engine. From the receiver, the air is drawn by the action of the circulating
pump i, through the valve j, pipes k, and valves 1.-The action of the part of the
pump above the piston b, in its down stroke is to draw off the water from the
receiver h, through the branch pipe m, the cock n, and the valve o, and in its up
stroke it forces the water thus drawn off, through the valve p, (Figure 2), and
pipe q, into the boiler with which it is connected.-A pipe a³, and stop-cock b³, are
provided for use between the hot-well or receiver. h, and the condenser c, in the
event of the air pump, that is to say, the part of the pump a, below the piston b,
failing to work, in order to give to the condenser c, the hot-well vacuum.-When
this arrangement of mechanism is applied to old engines, the hot-well is used as
the air receiver -The mechanism represented at Figuro 4, is that with which
the receiver or hot-well h, is fitted when the apparatus herein before described is !

page_text: applied to new engines.-The valve j, is rendered automatic and both acts as a
vacuum regulator and as a water throttle.-The use of this valve j, is in the first
place to prevent too high a vacuum being formed in the hot-well h, when tho
engines are racing. Should the vacuum exceed 22 inches of mercury, the small
valve r, opens inwards and admits air.-In the second place should the feed pump,
that is to say, the part of the pump above the piston b, fail to draw the water and
the water therefore rises in the hot-well or receiver h, to the level represented in
Figure 4, the said water would act upon the float 8, and close the throttle valve j,
and at the same time relieve the inlet air valve r, so that none of the fresh water
would be lost without lifting the large weighted valve t, (Figure 1).
At the junction between the pipes g, and m, there may be fitted a baffle box to
assist in the separation of the air from the water.
The pump represented on an enlarged scale at Figure 5, is constructed for pipe
condensers fitted outside the skin u, of the vessel, and in which condenser no
circulating pump is required.-The branch v, is connected to the end of the
condensing tubes w, at the lowest possible level and on one side of the keel x, so
that all the water condensed in the said tubes w, may run by its own gravity to
the suction valve y, through which it is drawn, along with any air that may have
accumulated by the up stroke of the piston b, while by the down stroke it is
discharged through the valves, and thence by the branch a', to the hot-well or
receiver h, thus forming a vacuum in the tubes w, of the condenser.-By the part
of the pump above the piston b, and by the down stroke of the said piston the air
is drawn through the branch b', which is connected by a pipe to the top of the hot-
well or receiver h, and through the valve c', and by the up stroke of the piston b,
this air is forced through the valve c³, and through the branch pipe d', and is
thereby conducted overboard.-A very small jet of water from the sea is allowed
to enter the upper part of the pump, or at some equivalent part, to prevent any
air from returning so that a vacuum of from 18 to 22 inches of mercury may be
maintained in the hot-well and by these means a higher vacuum is gained in the
condenser than by one large pump applied to the condenser and discharging to a
hot-well open to the atmosphere.
As represented on a reduced scale at Figure 6, the lower part or air pump end of
the pump may be made for large engines with a double suction so that when the
piston b, descends the water and air are forced by the lower side of the piston b,
and at the same time are drawn by the upper side of the said piston through the
valve e', and on the up stroke of the piston b, the water thus drawn through the
said valves, is forced through the valve g³, and is drawn off by feed action through
the pipe h¹.
It will be seen in the application of the mechanism hereinbefore described that
there is less friction on the engine also a reduction in the weight of the engine and
less liability of derangement of the several parts and a higher vacuum and hotter
feed water than hitherto is obtained.-The danger of starting (as at present) an
engine fitted with a large air pump, when a body of water has accumulated in the
condenser, by the application of these improvements to such engines is done away
with, and a great saving is also to be found in the substitution of metallic valves
for the ordinary India-rubber valves.
Having now described and particularly ascertained the nature of my said
Invention and the system, modo or manner in or under which the same is or may
be used or practically carried into effect, I would observe in conclusion that what
I consider to be novel and original and therefore claim as the Invention socured
to.me by the herein before in part recited Letters Patent is:-
First In surface condensing engines the arrangement of pumps, valves and their
connections for creating and maintaining a vacuum, wherein the upper part of the
said pump is used as a feed pump and the lower part thereof as an air pump
substantially as and for the purposes hereinbefore described with reference to the
accompanying Drawings.
Second. In surface condensing engines the connection between the receiver or

page_text: hot-well and the condenser consisting of the pipe a², fitted with the stop-cock b³,
substantially as and for the purpose hereinbefore described with reference to the
accompanying Drawings.
In Witness Whereof I the said Joseph Chapman have hereunto set my hand
and seal this Fifth day of July in the year of our Lord One thousand eight
hundred and eighty-three