IMPROVEMENTS IN VACUUM Dry
Year: 1881

page_text: LETTERS PATENT to William Hopkin Akester, of Glasgow, in the County of
Lanark, North Britain, for an Invention of "IMPROVEMENTS IN VACUUM
Drysenc
PROVISIONAL SPECIFICATION left by the said William Hopkin Akester at
the Office of the Commissioners of Patents on the 13th October 1881.
WILLIAM HOPKIN AKESTER, of Glasgow, in the County of Lanark, North Britain.
"IMPROVEMENTS IN VACUUM PUMPS."
The said improvements relate to what are called mercury or gravity pumps, and
consist in such arrangements as enable the vessel, exhausted by means of the
pump, to be removed from the pump itself while retaining the vacuum obtained,
and enable a vacuum to be produced with increased facility and efficiency.
In its most simple form the vacuum pump constructed according to this
Invention consists of an external tube having an internal lip a little distance from
the top, and this tube is preferably swelled out or contracted at parts instead of
being of uniform bore. The internal lip is ground on the top and inside so as to
take a stopper approximately air tight, the space above the lip serving as a
reservoir for a small quantity of mercury or other liquid to act as a lute to the
stopper.
The stopper forms part of a second tube so proportioned as that when the
stopper upon it is fitted into its place in the external tube before described, the
top of the internal tube projects a short distance beyond that of the external tube.
The top of this internal tube is enlarged and thickened so as to be conveniently
fitted with a cork or other device for making a good joint. A few inches from the
lower end of this internal tube it is thickened internally or fitted with a collar
internally, at which part on its underside and within it it is ground so as to take a
stopper. The stopper of this internal tube consists of a third tube sealed up at
both ends so as to constitute a rod, it being in the form of a tube for the sake of
lightness and buoyancy, and being ground at one end to form the stopper. After
the insertion of this last mentioned tube or rod within what has herein before been
called the internal tube, this latter is drawn away by a quick reduction to a
D...A31

page_text: capillary opening at its lower end, so as to retain the stopper rod within it and yet
to afford to this stopper rod sufficient movement to form passage past the stopper.
If the pump be used as a mercury pump the external tube must extend more than
32 inches below the lowest point of the internal tube, and if a fluid of less specific
gravity be employed this external tube must be proportionally lengthened. At the
bottom of the external tube is a flexible pipe of adequate length attached to a
reservoir of adequate size, so as that if the reservoir be lowered mercury in the
external tube will tend to flow into it, and if the reservoir be raised mercury in
the reservoir will tend to flow into the tube.
The action of the pump is as follows:-The vessel to be exhausted is attached
to the top of the internal tube by means of the cork or other device, and the
reservoir before described having been filled with mercury it is raised to such
height as is necessary to charge the pump, that is to say, to fill the external tube,
to raise the top stopper, and to flow above the top stopper of the same and
partially to flow by the capillary opening into the internal tube. The reservoir is
then lowered, and as the mercury begins to descend the top stopper shuts on to its
face, retaining a portion of the fluid above it so as to act as a lute. The mercury
below the stopper continues to flow downwards, and as no supply of air can be got
from the top stopper, air is sucked out by the capillary opening from the internal
tube, and thus, to some extent from the vessel to be exhausted. When the effort of
exhaustion is thus completed the reservoir is again raised and the mercury ascends
within the tube as before. A larger quantity this time enters by the capillary
opening of the internal tube, and by its weight tends to close the lower valve or
stopper, and at the same time to serve as a lute for this stopper. The air contained
within the space between the internal and external tubes above the capillary
opening of the former gradually, as the mercury rises, acquires more pressure and
at last lifts the stopper at the top and escapes; the mercury continues to flow, as
before, so as to expel all air and to lute the stopper, and then the process of
lowering is repeated. After by these means sufficient exhaustion is obtained the,
internal tube may be removed, while the vacuum is still retained by the contained
stopper and lute described, and another internal tube may be used to exhaust
another vessel. Several pumps may be attached to one reservoir.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
"
the said William Hopkin Akester in the Great Seal Patent Office on the
6th April 1882.
WILLIAM HOPKIN AKESTER, of Glasgow, in the County of Lanark, North Britain.
IMPROVEMENTS IN VACUUM PUMPS."
My said Invention relates to improvements in what are called mercury or
gravity pumps, and has for its objects to enable a vacuum to be produced with
increased facility and efficiency, and to enable the vessel exhausted by means of
the pump to be removed from the pump whilst retaining the vacuum in the said.
vessel.
The accompanying Drawing represents in vertical section the most simple form
of a pump constructed according to my Invention. The said pump consists of an,
external tube A which is preferably formed, as shewn, swelled out at its upper
part and contracted beneath instead of being of uniform bore throughout.
At a.
little distance from the top the tube is contracted to form an internal lip a which
is ground inside to form an approximately air tight seating for the stopper b,
forming part of an internal tube B so proportioned as that when the stopper b.
upon it is fitted into its place in the lip a of the external tube A, the part of the
internal tube B beneath the stopper is enclosed within the enlarged part of the
external tube A, the top of the internal tube B above the said stopper b projecting
a short distance beyond that of the external tube A. The top of the said internal
tube B is enlarged for receiving the stoppering corks c and d through which is
passed the tube forming the mouth of the vessel E from which the air is to be
exhausted. The internal tube B at a short distance from its lower end is formed
with an enlargement 62, at the upper part of which is an internal lip or collar b
ground internally to form a seating for the stopper or closing valve G. This
stopper G consists of a glass tube sealed up at both ends so as to constitute a rod,
it being hollow for the sake of lightness and buoyancy, and being ground at the.
upper end to form the stopper or valve which seats itself upon the ground internal
lip 6. After the insertion of the stopper rod G within the enlargement 6' of the
glass tube B, the said tube B is drawn away or reduced by a quick contraction at
its lower end below the said stopper rod G to a capillary opening 6*, so as to retain
the stopper within the enlargement b and yet afford to the said stopper rod
sufficient movement to allow it to descend from its seat 6s and give a passage over
the upper part of the said stopper rod and the seating 63. The detached Figure at.
the side of the main Figure represents a transverse section on the line 1, 2. The
stopper rod G is formed with a number of projections g for guiding it in its move-
ment in the enlargement 63, and at the lower end of the said stopper rod G are
projections or feet g³, g₁, to prevent the said stopper rod G when in its lowest.
position from closing the capillary opening 6' beneath it.
The external tube A is of a length in accordance with the specific gravity of the
liquid employed in the pump. For example, in the case of mercury, which is of
course the most convenient liquid to use, the said external tube A must extend
more than 32 inches below the lowest point of the internal tube B. At the bottom
of the external tube is a flexible pipe H of adequate length attached to a reservoir I
of adequate size containing the mercury or other liquid to be used in the pump, so.
that if this reservoir I be raised the mercury will tend to flow down from the said
reservoir up into the tube A, and if the said reservoir be lowered the mercury will
tend to flow from the tube A back into the reservoir I. A luting of mercury or

page_text: other liquid is placed above the cork c to prevent the passage of air. The enlarged
upper part of the external tube also serves as a receptacle for a small quantity of
mercury or other liquid to form a lute to the stopper b to prevent air from being
drawn into the tube A at this part. Sulphuric acid is applied in the customary
manner to the upper part of the tube A as a drying medium, the lip a² of the said
upper part being for the purpose of running off the acid and moisture from the top
of the mercury. The cock j is provided for the admission into the vessel E through
the tube B, of a hydrocarbon or other gas into the vessel E; or a cock j³ may be
used instead for this purposе.
The action of the pump is as follows:-The vessel E to be exhausted being
attached to the top of the internal tube B, as shewn, and the reservoir I having
been filled with mercury it is raised to such a height as is necessary to charge the
pump, that is to say, to fill the external tube A, to raise the top stopper b, and to
flow above the said stopper, and partially to flow by the capillary opening 6* into
the internal tube B; the reservoir I is thus lowered, and as the mercury begins to
descend the stopper b shuts on to its seat a, retaining a luting of mercury above it.
The mercury below the said stopper b continues to flow downwards, and as no
supply of air can be got into the tube A around the said stopper b air is sucked
out by the capillary opening b* from the internal tube B between the valve of the
stopper rod Ġ and its seat bs, and thus to some extent from the vessel E to be
exhausted. When the first effort of exhaustion is completed by the descent of the
mercury, the mercury is again caused to ascend within the tube A as before,
namely, by lifting the reservoir I; a larger quantity this time enters by the
capillary opening 6 of the internal tube B, and by its weight tends to close the
valve of the stopper rod G against its seat 63, and at the same time to serve as a
lute for this stopper. The air contained within the space between the internal
tube B and the external tube A above the capillary opening 64 gradually as the
mercury rises in the said space acquires more pressure, and at last raises the
stopper 6 and escapes. The mercury continues to flow as before so as to expel all
air and to lute the said stopper b, and thus the operation of lowering the mercury
is repeated. After by repetition of these operations sufficient exhaustion is obtained
the internal tube B may be removed from the external tube A, whilst the vacuum
is still retained in the vessel E by reason of the valve on the stopper rod G being
owing to the existence of the said vacuum pressed up upon its seat b³, the lutings
of mercury at the upper and lower parts of the tube B ensuring that there is no
passage of air into the said vessel E; the stem of the vessel E may then be sealed
up and the vacuum be thereby permanently secured therein and another internal
tube B, or the same internal tube B carrying another vessel to be exhausted being
placed in the external tube A of the pump a vacuum is created in this vessel as
before described and so on.
It will readily be understood that two or more pumps may be connected with
one reservoir if desired, the reservoir in this case being of sufficient capacity to hold
liquid enough for both or all the pumps.
Having now described and particularly ascertained the nature of my said
Invention, and the system, mode, or manner in or under which the same is or
may be used or practically carried into effect, I would observe in conclusion that
I do not limit myself to the precise details herein described and illustrated in the
accompanying Drawings, as the same may be varied without departing from the
nature of my Invention, but what I consider to be novel and original, and
therefore claim as the Invention secured to me by the herein-before in part recited
Letters Patent is,―
First. The combination of parts constituting the vacuum pump, substantially
as hereinbefore described and illustrated in the accompanying Drawings.
Second. In vacuum pumps, the employment of an internal tube such as (B),
and stopper or closing valve such as (G), arranged as hereinbefore described and
illustrated in the accompanying Drawings, so that the tube (B) carrying the vessel

page_text: from which the air has been exhausted can be removed from the other parts of the
pump without destroying the vacuum in the said vessel.
In witness whereof, I, the said William Hopkin Akester, have to this my
Specification set my hand and seal, this Twenty fifth day of January, One
thousand eight hundred and eighty two.
WILLIAM HOPKIN AKESTER. (LS.)