IMPROVEMENTS IN THE CONSTRUCTION OF APPARATUS FOR COMPRESSING OR CONDENSING AIR
Year: 1879

page_text: LETTERS PATENT to Thomas Cartledge, of Manchester, in the County of
Lancaster, for the Invention of " IMPROVEMENTS IN THE CONSTRUCTION OF
APPARATUS FOR COMPRESSING OR CONDENSING AIR."
Sealed the 28th October 1879, and dated the 30th April 1879.
PROVISIONAL SPECIFICATION left by the said Thomas Cartledge at the
Office of the Commissioners of Patents on the 30th April 1879.
THOMAS CARTLEDGE, of Manchester, in the County of Lancaster.
MENTS IN THE CONSTRUCTION OF APPARATUS FOR COMPRESSING OR CONDENSING
AIR."
"IMPROVE-
This Invention relates to the construction and arrangements of pumping apparatus
employed for compressing or condensing air for driving engines or for other purposes
where it is desirable to compress or condense atmospheric air to a very considerable
extent in the least possible time and at the smallest possible expenditure of power
or labor.
It is well known to persons conversant with air compressing machinery that
when only a moderate degree of compression is desired pumps of a moderately
large area may be employed, but when it is required to compress air to a very great
density it is necessary to contract the area of the air pumps and delivery pipes in
a corresponding ratio, and that the strength (and consequently weight) of the
pumps, pipes, and reservoir or compressed air chamber must be also increased
accordingly.
This being the case it has always been hitherto the practise in obtaining high
pressures to use only pumps of a very small area with pipes of a very small bore,
but as it will be evident that as such pumps and pipes can necessarily act upon
only a very small quantity of air at a time it will take a very long time to compress
a certain volume of air (beginning with the ordinary atmospheric pressure) to any
very great density; and it will be obvious that it would be of immense advantage
if the operation could be commenced with pumps of large capacity which could be
used with advantage at the commencement of the operation when the air is in its

page_text: normal state or only slightly compressed, and that the area of the pumps and pipes
should be gradually diminished in the same ratio as the density of the air becomes
increased by compression.
The above is the object of my Invention, and my improvements consist mainly
in combining and arranging a series of air pumps of gradually diminishing areas
in such a manner that the air at the ordinary atmospheric pressure is taken by the
first pump (or set of pumps) which is of the largest area, and is thereby compressed
to a certain density (say, for example, 40 lbs. to the square inch) into a reservoir
or vessel, which I will call No. 1.
The second pump (or set of pumps), which is of a diminished area (say one half),
does not draw the air from the external atmosphere, but gathers it from No. 1
reservoir, and condenses it still further (say to 80 pounds) into a second reservoir,
No. 2, which is only half the area of No. 1.
The third pump (or set of pumps), which is again of a diminished area (say one
quarter), gathers the compressed air fron No. 2 reservoir, and compresses it still
further (say to 120 pounds) into No. 3 reservoir, which is only one quarter the
area of No. 1, and so on, each pump (or set of pumps) decreasing in diameter and
taking the air from the last reservoir and condensing it into a still smaller space
till the required compression has been obtained.
It inust be observed that the pumps, pipes, and reservoirs diminish gradually in
area and are increased in strength from the first to the last, the first being adapted
to a very low pressure, and the last being suited to the highest pressure required;
and it will be evident that by these means the atmospheric air may be compressed
up to any required density very much quicker and with very much less labor and
cost than it could by cominencing from the ordinary atmospheric pressure and
working up to the density required, using during the whole process the very small
bore pumps (which are only really required at the finish) as hitherto invariably
practised.
I propose to give the same length of stroke to the plungers of all the pumps,
working them all by cranks or excentrics, being so arranged that they follow each
other, so that no two plungers are in the same position at the same time, and that
one half of them are rising while the others are being depressed; and it will thus
be evident that the pressure in each reservoir will assist the upstroke of the plunger
of the succeeding pump, and thus greatly diminish the amount of power required
to keep the pumps in action.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Cartledge in the Great Seal Patent Office on the 30th
October 1879.
THOMAS CARLEDGE, of Manchester, in the County of Lancaster.
MENTS IN THE CONSTRUCTION OF APPARATUS FOR COMPRESSING AIR."
<< IMPROVE-
This Invention relates to the construction and arrangements of pumping apparatus
employed for compressing or condensing air for driving engines or for other purposes
where it is desirable to compress or condense atmospheric air to a very considerablo
extent in the least possible time and at the smallest possible expenditure of power
or labor.
It is well known to persons conversant with air compressing machinery that
when only a moderate degree of compression is desired pumps of a moderately
large area may be employed, but when it is required to compress air to a very great
density it is necessary to contract the area of the air pumps and delivery pipes in
a corresponding ratio, and that the strength (and consequently weight) of the
pumps, pipes, and reservoir or compressed air chamber must also be increased
accordingly.
This being the case it has always been hitherto the practise in obtaining high
pressure to use only pumps of a very small area with pipes of a very sinnll bore,
but as it will be evident that as such pumps and pipes can necessarily act upon
only a very small quantity of air at a time it will take a very long time to compress
a certain volume of air (beginning with the ordinary atmospheric pressure) to any
very great density; and it will be obvious that it would be of immense advantago
if the operation could be commenced with pumps of large capacity which could be
used with advantage at the commencement of the operation when the air is in its
normal state or only slightly compressed, and that the area of the pumps and pipes
should be gradually diminished in the same ratio as the density of the air becomes
increased by compression.
Such being the nature and object of my said Invention, I will now proceed to
describe more in detail the manner in which the same is to be or may be performed
or carried into practical effect, and in order that the same may be clearly under-
stood I have annexed hereunto a Sheet of Drawings illustrativo thereof, and have
marked the same with figures and letters of reference corresponding with those in
the following explanation thereof.
Fig. 1 in the annexed Drawing represents a sectional elevation illustrating the
application of my Invention to a series of three pumps only, and Figs. 2, 3, and 4
are detached views showing the relative positions of the excentrics and plungers.
My improvements consist mainly in combining and arranging a series of air
pumps a, b, c, of gradually diminishing areas in such a manner that the air at the
ordinary atmospheric pressure is taken by the first pump a (or set of pumps) which
is (or are) of the largest area, and is thereby compressed to a certain density (say,
for example, forty pounds to the square inch) into a reservoir or vessel which I will
call No. 1.
b
The second pump 6 (or set of pumps), which is of a diminished area (say one
half), does not draw the air from the external atmosphere, but gathers it from No. 1
reservoir and condenses it still further (say to eighty pounds) into a second reservoir,
No. 2, which is only half the area of No. 1. The third pump c (or set of pumps),
which is again of a diminished area (say one quarter), gathers the compressed air
from No. 2 reservoir and compresses it still further (say to one hundred and sixty
pounds) into No: 3 reservoir, which is only one quarter the area of No. 1, and so
on, each pump (or set of pumps) decreasing in diameter and taking the air from the
last reservoir and condensing it into a still smaller space till the required compression
has been obtained.

page_text: It must be observed that the pumps, pipes, and reservoirs diminish gradually in
area and are increased in strength from the first to the last, the first being adapted
to a very low pressure and the last being suited to the highest pressure required;
and it will be evident that by these means the atmospheric air may be compressed
up to any required density very much quicker and with very much less labor and
cost than it could by commencing from the ordinary atmospheric pressure and
working up to to the density required, using during the whole process the very small
bore pumps (which are only really required at the finish), as hitherto invariably
practised.
I propose to give the same length of stroke to all the plungers d, d, d, the pumps
working them all by cranks or by excentrics e, e, e, on one main shaft f, f, the
cranks or excentrics being so arranged that they follow each other (see Figs. 2, 3,
and 4), so that no two plungers are in the same position at the same time, and that
one half of them are rising while the others are being depressed, and it will thus
be evident that the pressure in each reservoir will assist the up stroke of the plunger
of the succeeding pump, and thus greatly diminish the amount of power required to
keep the pumps in action.
Having now described the nature and object of my said Invention, together with
the manner in which the same is to be or may be performed or carried into
practical effect, I wish it to be understood that I claim as my Invention, the
improvements in the construction and arrangement of pumps for compressing or
condensing air, as herein before described and illustrated by the Drawing annexed,
or any mere imitation or modification thereof, constructed and operating in substan-
tially the same or a similar manner.
In witness whereof, I, the said Thomas Cartledge, have hereunto set my hand
and seal, this Twenty ninth day of October, in the year of our Lord One
thousand eight hundred and seventy nine.