AN IMPROVED APPARATUS FOR PREPARING OXYGENATED AIR
Year: 1884

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I, GEORGE FREDERICK REDFERN, of the General Patent Office, 4 South Street,
Finsbury, in the County of Middlesex, Patent Agent, do hereby declare the nature
of the said Invention for "AN IMPROVED APPARATUS FOR PREPARING OXYGENATED
AIR" and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
Heretofore, no apparatus has been known, by which air richer in oxygen than
atmospheric air, can be obtained by a perfectly automatic process of working,
through the medium of absorbing liquids.
In J. T. Mallet's apparatus (see British Patent N° 2137, July 15th 1869), which
has some features similar to mine, a hand lever and bell crank are used for
alternately opening and closing the exit pipes for the nitrogenated and oxygenated
portions of air, and the-air-compressor has to be stopped every time, when the
oxygenated air is being liberated from tho absorbing liquids. His apparatus is,
therefore, not automatic in its working, nor does it furnish a continuous stream of
oxygenated air.
The object of my Invention is, to devise an apparatus by means of which, with
the aid of absorbing liquids, an air mixture containing proportionally more oxygen
than atmospheric air, can be prepared by a perfectly automatic process, and the
said air mixture can be obtained in a continuous stream on a large as well as on a
small scale.
"
.
The apparatus is shown in the accompanying Drawing, in which Fig. 1 gives
the general arrangement of the different parts belonging to it; Figs. 2 & 3 show
longitudinal sections of the valves in their two principal positions of rest.
:
In Fig. 1, ac, represents an air-compressor. It may be of any suitable con-
struction. The pipe a connects it with the valve v 1. al and ar are two strong,
air-tight tanks, filled with such liquids which absorb oxygen more readily and in
proportionately larger quantities than nitrogen, when brought in contact with
then. As absorbing liquids I generally prefer water with a small addition of
glycerine or oil, to form a thin layer on top of the water. For brevity's sake
I shall call the tanks containing these liquids, simply "water tanks."

page_text: nl and nor are two other closed tanks, equally strong and air tight as the water
tanks. They serve for holding that portion of the introduced air, which is not
absorbed by the liquids in the water tanks. This portion consisting mostly of
nitrogen, I shall call these tanks " nitrogen tanks."
The water-tanks, a land ar, have each a horizontal diaphragm p, perforated
with many fine holes. They may have two or more such diaphragms, to insure a
fine sub-division of the introduced air, and a correspondingly perfect absorption.
The bottom parts of the water tanks are connected with the valve v1, through
the pipes b and c, and their top parts are connected with the valve v4, by the
pipes and h, and with the valves v3 and v2, by the pipes & and f.
The nitrogen tanks nl and nr, communicate with the valves v2, and v3, by
means of the pipos g, and e, and through these pipes and valves, in connection
with the pipes fand d, they communicate with the water tanks, a l and a r.
The four valves, v1, v2, v3 and v4 are shown as having a square shape with
flat surfaces, because in this shape, I can illustrate their working best. In practice,
they may have various other shapes and may be combined among themselves in
various other ways. These valvos may be similar to the slide valves of steam
engines, or similar to piston valves; or they may be made on the principle of
rotary valves, etc. In large apparatuses, they are best separate, cach valve being
in a chest by itself and supplied with its own valve rods.
In smaller apparatuses, the valves may be so combined as to form only one
machine, as in Figs. and 3. Or yet, two or three of the valves may be combined
in various ways, so as to form compound valves and be inclosed in two or three
valve chests, the valves being in the latter caso moved forwards and backwards by
two or three different valve rods. But the valves must, in all cases, be so arranged
and connected with one another by means of valve rods or otherwise, that they
always move simultaneously in the same direction, and always rest simultaneously
for the same length of time; so that, when one valve is in the forward position,
all four are in the same position, and when one is in the backward position, all of
them are in that position.
These four valves are moved forwards and backwards after certain intervals of
rest, by a suitable mechanical device worked by the engine in an automatic manner.
(This mechanical moving-device forms no part of the present Specification.)
The lengths of the intervals of rest between the two opposito motions of tho
valves, I shall call "minutes," no matter, whether their actual duration for any
given apparatus, bo longer or shorter than sixty seconds of time.
The mode of operating my apparatus is as follows: The air compressor (tc, is
worked continuously by any suitable motive power. The compressed air passes
through the pipe a, to the valve v1. In the forward position (Fig. 2.) of the
valve, its port m, establishes communication between the pipes a and b. The
pipo b, therefore, conveys the compressed air into the lower part of the water
tank al, during the first "minute."
At the expiration of the first "minute," the valve 1, is moved backwards into
its second position, as shown in Fig. 3. In this position the valve closes the pipe b,
and opens communication between the pipes a and c. The compressed air passes,
therefore, by the pipe c, into the lower part of the tank ar, during the second
"minute."
In this manner the water tanks a l, and ar, are filled with compressed air during
alternate "minutes."
The air being driven into the tank al, below the perforated diaphragm p, passes
upwards through the fine perforations, enters the water from below in numerous
fine streams and passes upwards through it in a state of fine sub-division. During
this upward passage, a certain portion of the air is dissolved and absorbed by the
water. The portion of air so absorbed, is in direct proportion to the pressure
prevailing in the water tank at the end of the first "minute."
That part of the introduced air, which is not absorbed and retained by the
water, rises at once to the top of the tank al, and is thence conveyed by the pipe f,

page_text: to the valve v2, where it passes through the port o, (Fig. 2.) into the pipe g. The
latter conveys it to the nitrogen tank n l.
d
The air driven into the water-tank ar, during the second "minute," enters the
water also from below, and passes through it in an upward direction in many fine
streams. It is likewise in part absorbed by the water, and in part rejected by it.
The pipe & conveys this rejected portion, consisting mostly of nitrogen, from the
top of the tank ar, to the port r, in valve v3, whence it is conducted by the pipe e,
into the second nitrogen tank nr, where it remains until the valves are shifted
again.
Thus, when during the first "minute," the water tank al is being filled with
compressed atmospheric air, the nitrogen tank nl, which communicates with
tank al, is being filled with the nitrogenated air not absorbed by the water in al,
and when, during the second "minute," the water tank ar is being filled with fresh
air from the compressor, the nitrogen tank nr is being filled with nitrogenated air
rejected by the water in the tank a r.
During the second "minute" the valves are in the backward position, Fig. 3,
the pipe is open at its valve end, and the pipe f, is closed by the valve v 2. The
communication between the water tank al and the nitrogen tank n is, therefore,
closed, and the nitrogenated air contained in nl, is separated from the contents of
the water tank al. Then the absorbed air liberates itself from the liquids in al,
and passes, by the pipe h, through the port n into the pipe i, and through the
latter into a holder, or to the place where it is to be used.
"
After the second "minute all the valves are moved forwards again into the
position shown in Fig. 2. In this position the pipe is open at its valve terminus,
while the pipe d is closed by the valve v3. The absorbed air in the water tank ar
is, therefore separated from the nitrogenated air contained in the tank nr, and
passes from the top of the water tank a r, through the pipe j, port n, and the pipe i,
into the holder, if there, is any, or to the place where the oxygenated air is to
be used.
Thus, the oxygenated air is furnished without interruption, the two tanks
containing the absorbing liquids, supplying it every alternate "minute" in regular
succession.
During the second "minute" the pipe g conveys the nitrogenated air from the
tank nl, (where it has accumulated during the first "minute") through the port o
(Fig. 3) and the exit opening &, into the atmosphere.
During the third "minute" the valves are in the forward position, Fig. 2. Then
the pipe e coming from the nitrogen tank nr, is open at its valve end, and the
nitrogenated air contained in the said tank escapes through the pipe e, port r, and
the exit opening k, into the atmosphere.
Thus, the tank nl exhausts its contents of nitrogenated air during the same
alternate "minutes" when the oxygenated air is allowed to liberate itself from the
absorbing liquids in the water tank al, with which it communicates during the
filling operation; and the tank nr exhausts its contents of nitrogenated air every
time, when the oxygenated air is liberated from the liquids in the water tank ar,
which occurs during those alternate "minutes" when the tanks a land n l, are
being filled with fresh atmospheric and nitrogenated air respectively.
The foregoing description shows that my apparatus furnishes a continuous
stream of oxygenated air, as long as the air compressor continues to drive
atmospheric air alternately into the two water tanks a land a r, and the four
valves, v1 v2 v3, and v4, are moved forwards and backwards after regular
intervals ("minutes") of rest.
If it is desired to obtain an air mixture, in which the oxygen is still more
concentrated than the first treatment yields it, then we put the pipe i, through
which the oxygenated air issues from the first apparatus, into communication with
a second similar, but much smaller apparatus, in place of the pipe a, and pass
the oxygenated air through the absorbing liquids of the second apparatus in the

page_text: same manner, as we have passed the atmospheric air through the liquids in the
first treatment.
This second treatment eliminates another portion of the nitrogen, and furnishes a
gas mixture, that contains a much larger per centage of oxygen than the first
treatment is capable of yielding.
A third and a fourth treatment concentrate the oxygen still more, but the
quantity of the resulting oxygenated air, is diminished by every subsequent
treatment.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed, I declare that what
I claim is
1. In an apparatus for preparing oxygenated air, the combination with an air
compressor of two strong, closed tanks (called "water-tanks") which are filled with
such liquids that absorb oxygen in comparatively larger proportion than nitrogen,
preferably with water having a layer of oil or glycerine on top, the two tanks
having each one or more horizontal perforated diaphragms p, and being connected
with the valve v 1, one by the pipe b, and the other by the pipe c, all substantially
as described and for the purpose specified.
In an apparatus for preparing oxygenated air, the combination with an air
compressor and two air-tight water tanks of two strong, hermetically closed air
tanks (called "nitrogen tanks") for the temporary storing of the nitrogenated air,
these two air tanks being so connected with the water tanks, through tho pipes g
and f, and e and d, and by the valves v2 and 3, that while the first water
tank al is being filled with compressed atmospheric air, the nitrogenated air can
pass out of the top of the said water tank into the first nitrogen tank n 1, and while
the second water tank ar is being filled with compressed. air, tbe non absorbed
(nitrogenated) portion of air can escape by the top of this second water tank into
the second nitrogen tank nr all substantially as described.
3. In an apparatus for preparing oxygenated air, the combination with an air
compressor two water tanks and two nitrogen tanks of four valves, which may be
of various shapes, such as slide valves, piston valves rotary valves etc. and which
may be either separate, so that each valve is in a chest by itself, or may be
combined into one, two or three compound valves, having one, two or three valve
chests and valve rods, but which must be so constructed and connected, that their
movements are always simultaneous, and that in one of their principal positions of
rest, as for example in their forward position, the communication is open between
the pipes a and b, through the port m, or some other equivalent means, between
the pipes fand g, through the port o between the pipes j and i through the port n,
and between the pipe e and the exit opening through the port while, at the
same time, the valve ends of the pipes c, and are closed by the valves v1 v3
and 4, and the coinmunication between the pipe and the exit opening is
closed by the valve v2;-and that, when the valves are in their other-backward-
position, the communication is open between the pipes a and c, through the port m,
or its equivalent, between the pipes d and e, through the port r, between the
pipes and i, through the port n, and between the pipe g and the exit opening k,
through the port o,while, at the same time, the valve ends of the pipes b, f, and j,
are closed by the valves v1 v2 and v 4, and the communication between the pipe e
and the exit opening k, is closed by the valve v 3, all substantially as described, and
for the purpose specified.
I
4. In an apparatus for preparing oxygenated air, the combination with an air
compressor two water tanks, two nitrogen-tanks and four valves of the pipe a,
connecting the air compressor with the valve v1, the pipe b, connecting the
valve v1 with the water tank a l, the pipe c, connecting the valve v 1, with the
water tank ar, the pipe f, connecting the top of the tank a l, with the valve v 2,
the pipe 9 connecting the valve 2, with the nitrogen tank, the pipe di
connecting the top of the tank ar with the valve 3, the pipe e connecting the

page_text: valve v3, with the nitrogen tank nr, the pipe h connecting the top of the water
tank al, with the valve v 4, the pipe j connecting the top of the water tank a r
with the valve v4, and lastly the exit pipe i, leading to a place where the
oxygenated air (resulting from the working of the apparatus) is either stored or
used, all substantially as described in the foregoing Specification and for the
purpose named.