An Improved Rotary Air or Exhaust Pump, Applicable also for Use as a Steam Engine Condenser.
Year: 1885

page_text: An Improved Rotary Air or Exhaust Pump, Applicable also for
Use as a Steam Engine Condenser.
WILLIAM MAXWELL Engineer 34 Claybrook Road Fulham S.W. I do hereby
declare the nature of my invention for AN IMPROVED ROTARY AIR OR EXHAUST
PUMP APPLICABLE ALSO FOR USE AS A STEAM ENGINE CONDENSER to be as follows:
Rotary pumps are used extensively for lifting water and exhausting air, but'
hitherto their use for the latter purpose bas been limited to comparatively low
degrees of exhaustion, to obtain moderate vacua direct acting pumps are usually
employed and for high vacua mercurial pumps chiefly of the " Sprengel" type
are used,
In a "Sprengel" pump the flow of mercury is generally rendered intermittent by
restricting the passage between the mercury supplying vessel and the "fall-tube,"
drops of mercury and portions of air enter the upper part of the "fall-tube"
alternately and successively, the mercury drops from air-tight pistons in the
"fall tube" which descend by gravity and carry the intervening layers of air:
downwards and outwards.
For the construction of the "fall tubes" glass tubes of fine bore only can be used
for if a certain size be exceeded the layers of air undergoing compression as they
descend acquire sufficient force to break through the superincumbent pistons of
mercury and thus prevent a high degree of exhaustion being attained. The
Sprengel pump is slow in action and is only used for extreme degrees of exhaustion
or what is known as "high vacua."
My improved rotary air or exhaust pump is designed to apply the principle of
the "Sprengel" to a form of pump capable of more extended application by which
quick exhaustion to a moderate or high degree of vacua may be economically
obtained and in which the compression of the enclosed portions of air or other
gaseous fluids by the weight of the mercury or other liquid employed may be wholly
or partially counteracted or avoided.
My improved rotary air pump may be constructed with any suitable number of
"fall" or discharge tubes or channels and may be employed to obtain the high
vacua required in the manufacture of incandescent electric lamps or for experimental
or other purposes.

page_text: .
My improved rotary air pump may also be applied as an air pump for condensing
steam engines or it may be used as a combined air pump and condenser.
It is obvious that the application of my invention to different purposes will
necessitate considerable variation in the material used and in the details of
construction, although the principle and action will be in each case substantially
the same, for the purpose of obtaining high vacua mercury or other suitable liquid
must be employed while for low or moderate vacua water may be used.
By centrifugal or centripetal force-evolved by rotation-or by both acting
together on a restricted or regulated supply of mercury or other suitable liquid
contained within or travelling through tubes channels or passages connected with
the vessel or vessels to be exhausted and with a central supply and circumferential
discharge of the liquid in use or a circumferential supply and central discharge or
by both combined I obtain an action or flow of the liquid and of the air or gaseous
fluid undergoing exhaustion which resembles or imitates the action or flow of the
mercury and air in an air pump of the "Sprengel" type.
In carrying out my invention I make use of a hollow spindle or shaft which may
be supported in a vertical position by a suitable framework and which may be
caused to rotate by any suitable means, the upper end of this spindle or shaft may
be connected with the receiver or other vessel or vessels to be exhausted in any
suitable manner.
In order to attain a high degree of exhaustion it is necessary that the connection
between the rotating spindle or shaft and the receiver should be perfectly airtight
and that the means employed to ensure this should be incapable of contaminating
the liquid or of vitiating the vacuum.
I prefer to make use of the following device to fulfil these conditions when the
pump is designed to obtain high vacua by the use of mercury and to work under
atmospheric pressure. I connect the receiver or other vessel or vessels to be
exhausted to a fixed tube whose internal diameter or bore exceeds the diameter of
the upper part of the hollow spindle or shaft and whose length is greater than that
of the barometric column, into this fixed tube the hollow spindle or shaft passes-
without touching-to a distance greater than the height of the barometric column.
From a point on the hollow spindle or shaft below that to which the fixed tube
descends, a casing or vessel of cylinderical or other suitable form rises and surrounds
or encloses the mouth and the lower portion of the fixed tube without touching it.
Into this casing or vessel mercury is poured sufficient in quantity to fill the annular
space between the rotating spindle and the fixed tube and to cover and seal the
mouth of the fixed tube when at the highest stage. of exhaustion. As the process
of exhaustion proceeds the mercury will rise between the rotating spindle and the
fixed tube until it attains the height due to the atmospheric pressure. . When it is
intended to employ any other liquid than mercury or to work the pump under a
pressure either greater or less than that of the atmosphere the length of the spindle
and tube may be suitably proportioned.
From a lower part of the hollow spindle or shaft the tubes or channels which
effect the exhaustion radiate or curve, these tubes or channels may be of any
suitable size form or construction and in any required number, they may be
attached to the spindle or shaft in any suitable manner and may open into the
hollow of the spindle or shaft or may be connected there with either directly or
indirectly.
The supply of mercury necessary to effect exhaustion may be contained in a
vessel or casing affixed to the hollow spindle or shaft and surrounding or enclosing
the tubes or channels, the mercury may pass from the central part of the vessel or
casing either directly or indirectly to the tubes or channels and the flow may be
restricted or regulated in any suitable manner, the tubes or channels will discharge
the mercury and the air gases or vapours which they are exhausting near the
periphery of the casing or vessel, to facilitate the return of the mercury to the
central part of the vessel or casing curved partitions vanes or channels may be
affixed or formed therein so as to cause a centripetal flow of the mercury.

page_text: The pump may be wholly or partially enclosed or surrounded by an outer casing
or envelope which may be maintained at any required temperature.'
Any suitable and easily fusible metal or alloy may be used instead of mercury.
The principal supports of the pump and the gearing by which it is driven may
be placed beneath the mercury casing or vessel.
The pump may be constructed to act on the compound principle.
When the pump is designed for low or moderate vacua the vessel containing
mercury or other liquid may be fixed and the pump caused to revolve therein, and
the spindle may be fitted with a stuffing box or other suitable contrivance.
When employed as an exhaust pump for a condensing engine the water used may
be discharged into a separate vessel from which the boiler feed water may be drawn
or when the supply of water is limited and an open space available the pump while
condensing the exhaust steam may act as its own refrigerator by discharging the
heated water into the air in the form of spray and thus ensure rapid cooling, with
this pump a separate condenser is not necessary, the steam may pass directly from
the cylinder to the pump and there undergo condensation..
The exhausting tubes or channels may be arranged so as to act either to or from
the centre of the pump.

page_text: An Improved Rotary Air or Exhaust Pump, Applicable also for
Use as a Steam Engine Condenser.
I, WILLIAM MAXWELL, of 34 Claybrook Road, Fulham, in the County of
Middlesex do hereby declare the nature of this invention and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement :-
Rotary pumps are used extensively, for lifting water and exhausting air but
hitherto their use for the latter purpose has been limited to comparatively low
degrees of exhaustion, to obtain moderate vacua direct acting pumps are usually
employed and for high vacua mercurial pumps, chiefly of the "Sprengel" type
are used.
In a "Sprengel" pump the flow of mercury is generally rendered intermittent
by restricting the passage between the mercury supplying vessel and the "fall-
tube," drops of mercury and portions of air enter the upper part of the "fall tube"
alternaternately and successively, the mercury drops form pistons in the "fall-
tube" which descend by gravity propelling the intervening layers of air.
For the construction of the "fall-tubes," glass tubes of fine bore only can be used,
for if a certain size be exceeded, the layers of air undergoing compression, as they
descend, acquire sufficient force to break through the superincumbent pistons of
mercury and thus prevent a high degree of exhaustion being attained. The
Sprengel pump is slow in action and is only used for extreme degrees of exhaustion
or what is known as "high vacua."
My improved rotary air or exhaust pump is designed to apply the principle of
the Sprengel to a form of pump capable of more extended application by which
quick exhaustion to a moderate or high degree of vacuum may be economically
obtained.
My improved rotary air or exhaust pump may be constructed with any suitable
number of "fall" or discharge tubes or channels and may be employed to obtain
the high vacua required in the manufacture of incandescent electric lamps or for
experimental or other purposes.
My improved rotary air pump may also be applied as an air pump for con-
densing steam engines or it may be used as a combined air pump and condenser.
It is obvious that the application of my invention to different purposes will
necessitate considerable variation in the materials used and in the details of con-
struction although the principle and action will be in each case substantially the
same, for the purpose of obtaining high vacua mercury or other liquid metal must
be employed while for low or moderate vacua water or other liquid may be used.
By centrifugal or centripetal force produced by rotation or by both acting
together on a restricted or regulated supply of mercury or other liquid contained
within or travelling through passages connected with the vessel or vessels to be
exhausted, and with a central supply and circumferential discharge of the liquid
in use, or a circumferential supply and central discharge or by both combined
I obtain a flow of the liquid and of the air or gaseous fluids undergoing exhaustion

page_text: which resembles or imitates that of the mercury and air in an air pump of the
Sprengel type.
In carrying out my invention I make use of a vertical hollow spindle or shaft
which is caused to rotate, the upper end of the spindle or shaft being connected air
tight to the receiver or vessel to be exhausted.
.
In order to make an air tight connection of the revolving hollow spindle to the
-vessels that are exhausted I prefer to use a hydraulic joint giving sufficient height
of column to balance the external pressure.
From a lower part of the hollow spindle or shaft the tubes or channels which
effect the exhaustion radiate or curve in any desired number.
The mercury necessary to effect exhaustion passes to the tubes or channels, the
flow being restricted or regulated so as to admit the mercury. only in separate
successive portions. The tubes or channels discharge the mercury and the air
gases er vapours which they are exhausting near the periphery of the casing or
vessel, and in order to facilitate the return of the mercury to the central part of
the vessel or casing, curved partitions vanes or channels may be affixed or formed
therein so as to cause a centripetal flow of the mercury.
The pump may be wholly or partially enclosed or surrounded by an outer
casing or envelope, and the space within this may be maintained at any required
temperature and pressure.
Certain fusible alloys may be used instead of mercury.
The pump may be constructed to act on the compound principle, that is to say,
to exhaust by stages, one pump producing moderate exhaustion, and another
producing a higher degree.
When the pump is designed for low or moderate vacua, the vessel containing
mercury or other liquid may be fixed and the pump caused to revolve therein..
When employed as an exhaust pump for a condensing engine the water used
may be discharged into a separate vessel from which the boiler feed water may be
drawn, or when the supply of water is limited and an open space available, the
pump while condensing the exhaust steam may act as its own refrigerator by dis-
charging the heated water into the air in the form of spray, thus ensuring rapid
cooling.
With this pump a separate condenser is not necessary as the steam may pass
directly from the cylinder to the pump and there undergo condensation.
The exhausting tubes or channels may be arranged so as to act either to or from
the centre of the pump.
Fig. 1 of the accompanying drawings is a vertical section and Fig. 1° is a plan
of a rotary pump according to my invention arranged to act in lieu of a Sprengel
pump for producing a high degree of vacuum A is a basin containing mercury, and
having a central hollow boss B from which curved tubes O of small bore extend
upwards and outwards to an annular trough rim D. From the centre of the boss B
a tube E extends upwards through a bearing, and within a stationary tube F which
is connected to the lamp bulbs or other vessels that have to be exhausted. A cup G
is charged with mercury, which rising in the annular space between E and F
constitutes a hydraulic joint, the height of column being made sufficient to balance'
the difference between, the external and the internal pressures. When the basin A
and the apparatus within it are caused to revolve in the direction of the arrow,
mercury with which the basin is charged entering the tubular part of the spindle
by apertures and passing by narrow channels the plug b₁, finds its way in
separate successive portious into the tubes C and these portions are propelled along
these tubes by centrifugal force, each portion of mercury constituting a fluid piston
which carries away in front of it a portion of air which has descended the tube E
and entered the tubes C. The mercury is discharged from the tubes C into the
trough rim D whence it overflows into the basin A returning to the centre to
supply the tubes C afresh. The air carried by the mercury along the tubes C
separates at the rim and escapes through apertures in the lid of the basin. By
enclosing the whole apparatus in a chamber exhausted by an ordinary air pump,

page_text: so that the pressure acting. against the outflow along the tubes C is considerably
below that of the atmosphere, the rotary pump may be rendered effective at
moderate velocity for producing a high. degree of vacuum. Obviously, instead of
mercury, a metal fusible at a moderate temperature may be employed the apparatus
being kept sufficiently. hot to maintain its fused condition.
According to the modified form of pump shown in Fig. 1b, the lid O of the
basin A is stationary and has suspended from it a stationary shelf s along which
the mercury discharged from the tubes C returns to supply the hollow of the boss B
through small holes.
Fig. 2 is a vertical section shewing a rotary pump according to my invention
applied as an air pump for a steam engine in conjunction with means of con-
densing the steam. In this arrangement, water entering by a distributing nozzle H
meets the steam entering the pipe F and condenses it. The water of injection and
condensation along with such air as may be present descending to the hollow
boss B is driven out along the revolving tubular arms C and overflows the trough
rim D into the tank K, from which part of the condensing water supplied to the
nozzle H may be drawn. The tank K may extend entirely under the pump and
the water instead of entering above by the nozzle H may enter the hollow boss B
from below and be distributed by a perforated nozzle within the passage descending
to the boss.
Fig. 3 is an elevation partly in section shewing a modified form of rotary air
pump in which centripetal as well as centrifugal action is applied. In an upper
tank L in which the steam entering at F is condensed by water issuing from a
nozzle H there is a revolving disc M of which Fig. 8 is a plan, having in it
channels curved forwards along which water is propelled towards the hollow
centre. The water descends a tubular spindle B past a check valve to a second
revolving disc N, of which Fig. 3b is a plan, having channels curved backwards
opposite to those in M, along which channels the water is propelled outwards.
Obviously either the upper part of this pump might be used alone to act
centripetally, or the lower part might be used to act centrifugally, or both may
act together as shewn in Fig. 3.
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. The construction and use of a rotary pump, substantially as herein described
with reference to Figs. 1, 1° and 1b for effecting exhaustion by the centrifugal
discharge of portions of mercury or other liquid acting as fluid pistons propelling
the air which occupies the discharge tubes.
2. The construction and use of a rotary pump, substantially as herein described
with reference to Fig. 2, operating as an air pump for a steam engine by the
centrifugal discharge of the water of injection and condensation.
3., The modified construction of rotary pump to operate as an air pump for a
steam engine, substantially as described with reference to Figs. 3, 3 and 3b, by
combined centripetal and centrifugal action on the water of injection and con-
densation, or by either centripetal or centrifugal action alone.
..נים
sa 1000