Year: 1897

page_text: A communication by RUDOLF BERGMANS, of бд, Fischergasse, Breslau, in the
Empire of Germany, Engineer.
1
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both
in the County of Lancaster, 118, New Street, Birmingham, in the County of
Warwick, and 322, High Holborn, in the County of Middlesex, Civil Engineer, do
hereby declare the nature of this invention to be as follows:-
In rapid working piston- or plunger pumps for liquids, such shocks arise in the
pump at the commencement of the compression period in consequence of the
sudden changes of pressure, that the working parts are considerably endangered
and also the valves bump very heavily.
This invention relates to an arrangement for preventing these shocks and consists
in having two pumps with plunger pistons, having an equal suction or compres-
sion action, being connected with one another in such a way that the pressure valve
of the first pump, the piston of which draws from the pump kettle, separates the
two pump chambers from one another, the pump chamber of the second pump
strictly speaking being thus formed of a part of the pressure pipe of the first
pump, and the pressure valve of the first pump forming at the same time the
suction valve of the second pump. The chamber of the second pump, which latter
is also provided with a pressure valve, is further provided with an air hood or
dome capable of producing during the suction period of both pumps merely an
unloading but not an opening of the pressure valve of the first pump which latter
has up to then been standing under the pressure of the column of liquid existing
in the lift pipe, an expansion of the air in the air hood only taking place, the pres-
aure of which air at the commencement of the auction period is equal to that of
the said pressure height.
In one form of construction the suction valve is arranged below the plunger of
the first pump, the pressure valve of said pump having a plunger for drawing the
liquid out of the pump kettle. The part of the pressure pipe above the pressure
valve is shut off from the actual lift pipe by means of a second pressure valve in
the air or wind chest and forms the chamber of a second pump which latter is also
provided with a plunger. This second pump chamber is provided, above the
pressure valve of the first pump, with an air hood or dome, the air space of which
may be diminished or increased by screwing the air hood up or down on its sup-
port. The plunger of the first pump is rigidly connected with the plunger of the
second pump by means of suitable rods and cross pieces, thereby causing both
plungers to move in the same dircotion.
Above the pressure valve of the second pump there is an air chest connected
with the lift pipe.
During the suction period when the plunger of the first pump draws the liquid

page_text: out of the pump kettle, the plunger of the second pump increases the space between
the pressure valves of both pumps. The air contained in the air dome (the pres-
sure of which air at the commencement of the suction period is equal to the height
of pressure) expands and may be lowered to that of the height of suction up to
the completion of the suction period.
1
On the commencement of the pressure period, the pressure, existing not only
in the first pump but also in the space between the pressure valves of both pumps,
is thus reduced and therefore the air in the dome is again compressed until its
pressure again equals the height of pressure. The pressure valve of the second
pump then only opens and the liquid compressed by the plunger of the first pump
passes into the air chest and from 'there into the lift pipe.
It is of advantage for the working of the pump to carry the expansion of the
air in the dome so far that shortly, before the completion of the expansion period
the final pressure is equal to, or less than the atmospheric pressure which may be
easily attained by the insertion of an air suction valve. In this case the plunger
of the second pump will draw in atmospheric air through said valve and thus cause
the air hood or dome to remain sufficiently filled with air. If it is not desired to
have so low a pressure at the end, air must be introduced into the dome by means
of a separate air pump in order to maintain a sufficient quantity of air therein.
The introduction of air into the dome is necessary on account of the losses caused
by absorption and loss of air in the liquid..
1
1
During the suction periods, the plunger of the second pump alone effects the
expansion of the air, whilst during the pressure periods the plungers of both pumps
cause compression of the air in the dome and consequently the pressure of the same-
rises more rapidly during the pressure periods than it descends during the suction
perioda.
i
The distances which the plungers of both pumps have to travel until the pressure.
valve of the second pump opens, may be regulated as desired and they depend on
the proportions of the length of stroke, or where the plunger strokes are equal,
on the proportions of the plunger sections.
.
"
1:
"The volume of air in the dome is determined according to the length of stroke
of the plunger of the first pump. During the working of the pump, by altering
the volume of air in the hood or dome, according to requirements, the course of
both plungers may be similarly altered within certain limits and this is attained
by screwing the dome up and down on its support.
The distances travelled by the plungers are made greater, the greater the
number of revolutions of the pump in order to produce a gentler lift of the pressure
valve.
A sudden change of pressure consequently no longer takes place on the change
of stroke and at the commencement. of the pressure period. By the combined
action of the two pumps, the plunger pressure gradually increases to a maximum,
a steady motion of the different working parts of the pumps being obtained.
In addition by this arrangement of pump a gentle lifting of the pressure valves
.is obtained.
The pressure valve of the first pump is at the commencement of the pressure
period almost or entirely unloaded so that it is lifted off the valve seat on a very
small excess of pressure. The pressure valve of the second pump is also lifted
off its seat equally easily and free from shock, as the equalization of the pressures.
below and above the valve of the second pump (which at the commencement, of
the pressure periods vary) takes place gradually and under the influence of the air
compression in the dome.
1
Another arrangement, of the compound or duplex pump consists in combining
the plungers of both pumps into one having different diameters, and an annular
surface forms the effective section of the plunger of the second pump. Further,
the pressure valve of the second pump is arranged directly above the pressure valve
of the first pump and the air hood or dome over the actual pump chamber of the
second pump.

page_text: Another form of arrangement is similar to the arrangement described, only the
air dome is placed on the connecting pipe instead of over the pump' chamber of
the second pump.
Another arrangement consists in placing the second pump beside the first pump,
in which case the movement of the plunger is also in the same direction.
Another arrangement consists in having two pumps arranged beside the first
pump and connected with one another by means of short pipes.
Various other arrangements of this compound or duplex pump may be adopted,
such for instance as twin-pumps, double acting plunger or piston pumps and the
like. In these various arrangements the working of the pumps is similar to that
hereinbefore described.
Instead of the disc valves hereinbefore described any form of valve may be
employed as may be found most suitable.
Dated this 21st day of June 1807
:
A communication by RUDOLF BERGMANS, of 511, Fischergasse, Breslau, in the
Empire of Germany, Engineer.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both
in the County of Lancaster, 118, New Street, Birmingham, in the County of
Warwick, and 322, High Holborn, in the County of Middlesex, Civil Engineer, 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
In rapid working piston or plunger pumps for liquids such shocks arise in the
pump at the commencement of the compression period in consequence of the sudden
changes of pressure, that the working parts are considerably endangered and also
the valves bump very heavily.
This invention relates to an arrangement for preventing these shocks and con-
sists in having two pumps arranged in connection with one another in such a way
that the pressure valve of the first pump, the piston of which draws from the pump
kettle, separates the two pump chambers from one another, the pump chamber of
the second pump strictly speaking being thus formed of a part of the pressure
pipe of the first pump, and the pressure valve of the first pump forming at the
same time the suction valve of the second pump. The chamber of the second
pump, which latter is also provided with a pressure valve, is further provided with
an air hood or dome capable of producing during the suction period of both pumps
merely an unloading but not an opening of the pressure valve of the first pump,
which latter has up to then been standing under the pressure of the column of
liquid existing in the lift pipe, an expansion of the air in the air hood only taking
place, the pressure of which air at the commencement of the suction period is equal
to that of the said pressure height.
Several forms of construction of such coupled pumps are shown in the accom-
panying drawings, in which,
Figure 1 is a partial vertical section;
Figure 2, a sectional end view;
Figure 3, a partial horizontal section;
Figure 4, a partial vertical section of a modified form of pump;

page_text: Figure 5, a diagram of one pump A;
Figure 6, a diagram of the other pump B;
Figure a modified form of the pump shown in Figure 4;
Figure a modification of the pump shown in Figure 1;
Figure 9, a further modification of the pump;
Figure 10, another modification of same; and
Figures 11, 12 and 13, a further modification;
Figure 14, a vertical section of a spring plunger for preventing shocks; and
Figure 15, a diagram of the application of Figure 14 to a coupled pump.
In the form of construction shown in Figures 12 and 3, the suction valve Vs is
arranged below the plunger P of the first pump A, the pressure valve V d of said
pump having a plunger for drawing the liquid out of the pump kettle S. The
part of the pressure pipe above the pressure valve Vd is shut off from the actual
lift pipe d by means of a second pressure valve V¹d in the air or wind chest and.
forms the chamber of a second pump B, which latter is also provided with a
plunger p. This second pump chamber is provided above the pressure valve Vd
of the first pump, with an air hood or dome 7, the air space w, Figure 1, of which
may be diminished or increased by screwing the air hood / up or down on its sup-
port. The plunger P of the first pump A is rigidly connected with the plunger p
of the second pump B by means of suitable rods s.and cross pieces thereby causing
both plungers to move in the same direction, Figure 3.
Above the pressure valve V₁d of the second pump B there is an air chest W con-
nected with the lift pipe d.
During the suction period when the plunger P of the first pump A draws the
liquid out of the pump kettle S, the plunger p of the second pump. B increases
the space between the pressure valves V d and V₁d of both pumps. The air con-
tained in the air dome (the pressure of which air at the commencement of the
suction period. is.equal to the height of pressure) expands and may be lowered to
that of the height of suction up to the completion of the suction period.
On the commencement of the pressure period, the pressure existing not only
in the first pump. A but also in the space between the pressure valves V d V₁d of
both pumps is thus reduced and therefore the air in the dome 7 is again compressed
until its pressure again equals the height of pressure. The pressure valve Vid
of the second pump then only opens and the liquid compressed by the plunger P
of the first pump A passes into the air chest W and from there into the lift pipe d.
It is of advantage for the working of the pump to carry the expansion of the
air in the dome so far that shortly before the completion of the expansion period
the final pressure is equal to, or less than, the atmospheric pressure which may
be easily attained by the insertion of an air suction valve v, Figure 1. The pres-
sure of the air drawn through the air valve is kept less than the atmospheric
pressure by means of throttling. For this purpose the air valve is loaded by
means of a spring under such tension that the valve only opens when the pressure
in the air hood or dome has become less than the atmospheric pressure. Thus
the pressure in the air hood or dome may be brought to the suction height.
In this case the plunger p of the second pump B will draw in atmospheric air
through said valve v and thus cause the air hood or dome to remain sufficiently
filled with air. If it is not desired to have so low a pressure at the end, air must
be introduced into the dome by means of a separate air pump in order to main-
tain a sufficient quantity of air therein. The introduction of air into the dome l
is necessary on account of the losses caused by absorption and loss of air in the
liquid.
In the diagrams of the pumps A and B shown in Figures 5 and 6, the former
represents by the letters a b c d f the diagram of the pump A and the latter by
the letters g h i j the diagram of the pump B. is the atmospheric line, o the null
line, h, the height of pressure and 2 the height of suction. The curve h shows
the expansion of the air in the dome 7 during the suction period and the similar
curves d f and i j the compression of the same during the pressure periods. Ath

page_text: the like. In these various arrangements the working of the pumps is similar to
that herein before described:
11:
Instead of the disc valves hereinbefore described any form of valve may be
employed as may be found most suitable.
1:
In the modification shown in Figures 11, 12 and 13, instead of the plungers
being rigidly connected with one another, they are arranged if necessary with
independent driving gearing. In order to allow of the method of driving and
of the plungers and their mode of working being better understood in Figure 11
the pump B is shown underneath the pump A. In actual execution however 'they
are arranged side by side as shown in Figures 12 and 13 and the 'two plungers P
and are driven by a common shaft. It is not a necessary condition that the
driving of the two plungers be so regulated that the commencement of the pres-
sure- and suction-periods take place simultaneously. Rather it is somewhat
advantageous in these coupled pumps if the two plungers are so operated that
the smaller plunger p of the pump B lags a certain extent behind the larger
plunger P of the pump A, that is to say if the plunger P commences to press or
draw as the case may be, before the piston p. As shown in Figure 11 the crank
follows the crank at a certain angle. The plunger P has thus commenced the
pressure period whilst the piston p is still for a short time sucking, until after
the reversal of the movement of the plunger p both plungers press together. The
plunger I will also commence the suction period whilst the plunger ? is still
pressing.
By this mode of working of the plungers when the pressure and suction periods
both plungers are mutually adjusted to the most favourable limits, there are
ined:
1. That at the commencement of the pressure period the pressure in the pump
ambers rises more slowly than when the plungers press simultaneously, as the
plunger p has still a suction action, whilst the plunger P is pressing.
2. That the closing of the third valve Vid is more precise and more gentle as
shortly before the closing of the said valve V' d the speed of the liquid through the
said valve is considerably less than when both valves press simultaneously.
The plunger p still presses after the plunger P has commenced the suction period,
and thus shortly before the closing of the third valve Vid the quantity of liquid
pressed by the always smaller piston p is less, and consequently the speed of the
liquid through the valve Và is smaller. The lifting and closing the valves
may be made gentler if instead of the dome in the pump chamber of the second
pump B an apparatus be arranged representing an elastic wall so that the interior
of this pump chamber may automatically enlarge and contract.
Figure 14 shows such an arrangement consisting of a plunger F under the pres-
sure of a spring f. In the lowest position the plunger piston is retained by a 4
stuffing box o as shown in Figure 14. The downward movement of the plunger
may however be limited in any other suitable manner.
When the plunger is in the lowest position, the pressure of the liquid in the
pump chamber of the second pump B has reached the lowest extent which takes
place after the completion of the suction period. When the pump plunger com- 4
mences to press, the plunger F which at first is only slightly pressed by the
spring, f, is gradually forced out of the chamber K and thus the spring is com-
pressed more and more until the pressure of the same becomes great enough to
overcome the maximum pressure of the liquid exerted on the plunger (corre-
sponding to the height of pressure). At this moment the third valve V₁d opens 5
and the liquid in the pump chambers is forced to the pressure pipe. After the
completion of the pressure period the small plunger which now has a suction
action, gradually draws the plunger F into the chamber K, the spring f is less
and less compressed
of the seculd pumer and thus also the pressure of liquid in the pump chambers
Figure 15 shows diagrammatically the arranged of the pump A is unloaded. 5
plunger piston in a coupled pump.
t of the spring weighted

page_text: the pressure of the air in the dome is equal to atmospheric pressure and during the
small piston course the plunger 2 draws in atmospheric air through the valve v.
The curvesh and i j differ from one another.
During the suction periods, the plunger p of the second pump (Figures 1 to 3)
alone effects the expansion of the air, whilst during the pressure periods the
plungers Pp of both pumps cause compression of the air in the dome and conse-
quently the pressure of the same rises more rapidly during the pressure periods
than it descends during the suction periods.
The distances, Figures 5 and 6, which. the plungers p and P respectively of
both pumps have to travel until the pressure valve Vid of the second pump B
opens, may be regulated as desired and they depend on the proportions of the
length of stroke, or where the plunger strokes are equal, on the proportions of
the plunger sections.
If the section of the plunger p be indicated by f and that of the plunger P by F,
the distance will be greater the greater the proportion f F is made.
The volume of air in the dome is determined according to the length of
stroke of the plunger . During the working of the pump, by altering the
volume of air in the hood or dome / according to requirements the course or
respectively of both plungers may be similarly altered within certain limits and
this is attained by screwing the dome up and down on its support k.
The distances travelled by the plungers are made greater, the greater the num
ber of revolutions of the pump in order to produce a gentler lift of the pressure
valve V¹ d.
As may be seen from the two diagrams no sudden change of pressure con
quently any longer takes place on the change of stroke and at the commencem
of the pressure period. By the combined action of the two pumps A and B,
plunger pressure gradually increases to a maximum, a steady motion of the differe
working parts of the pumps being obtained.
In addition by this arrangement of pump a gentler lifting of the pressure valves
is obtained.
The pressure valve Vd of the first pump A is at the commencement of the
pressure period almost or entirely unloaded so that it is lifted off the valve seat
on a very small excess of pressure. The pressure valve V₁d of the second pump B
is also lifted off its seat equally easily and free from shock as the equalisation of
the pressures below and above the valve Vid of the second pump (which at the
commencement of the pressure periods vary) takes place gradually and under
the influence of the air compression in the dome 1.
Another arrangement of the compound or duplex pump is shown in Figure 4
and consists in combining the plungers P and 2 of both pumps into one having
different diameters, and an annular surface F forms the effective section of the
plunger of the second pump. Further, the pressure valve V'd of the second
pump is arranged directly above the pressure valve Vd of the first pump and the
air hood or done over the actual pump chamber B of the second pump.
Figure 7 shows diagrammatically another form of arrangement similar to the
arrangement just described and shown in Figure 4, only the air dome / is placed
on the connecting pipe h instead of over the pump chamber of the second pump.
Figure 8 is a similar arrangement to that shown in Figure 1 but with com-
bined plungers of different diameters.
Another arrangement shown in Figure 9 consists in placing the second pump B
beside the first pump A in which case the movement of the plunger is also in the
same direction.
Another arrangement shown in Figure 10 consists in having two pumps B
arranged beside the first pump A and connected with one another by means of
short pipes u.
s compouna or uplex pump may be adoptea,
Various other arrangementaps, double acting plunger or piston pumps and
such for instance as twin-r

page_text: Instead of plunger pistons other suitable pistons known in technology may of
course be employed and instead of a steel spring, other suitable spring resistances.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as communicated to
me by my foreign correspondent I declare that what I claim is:-
:-
1. A coupled pump for liquids, consisting of two pump chambers separated by
the pressure valve (d) of the main pump (A) which draws the liquid out of the
pump kettle (S); plungers (1' and p) having a simultaneous sucking or forcing
action; and an air dome (4) arranged on the pump chamber (h) of the second
pump (B); whereby there is obtained during the common suction period an ex-
pansion and corresponding reduction of pressure of the air compressed at the
commencement of the suction by reason of the height of pressure, and simul-
taneously an unloading of the pressure valve (Vd) of the main pump by means
of the suction action of the second pump (B) whilst during the pressure period
the pressure bearing on the said valve is increased very gradually by the action
of both plungers compressing, the air in the dome (2) up to a maximum (to a pressure
corresponding to the height of pressure) thereby securing a movement of the
moving parts and of the valves free from shock, substantially as hereinbefore
described.
2. A form of construction of the hereinbefore described coupled pump for liquids,
characterised by each plunger of the coupled pump being separately operated by
means of cranks and driving rods, the plunger (p) of the second pump (B) lagging
to a certain extent behind the plunger (P) of the main pump (A); substantially
as hereinbefore described:
3. A form of construction of the hereinbefore described coupled pump for liquids
to adapt it to suit the volume of air which is alternately subjected to expansion
and compression, to the amount of stroke of the plunger (p) producing the expan-
sion, characterised by the air dome (7) being adapted to be enlarged or diminished
according to requirements and being provided with an air suction valve (v),
whereby the final pressure in the auction period may be regulated and the loss of
air resulting from absorption and from being carried along with the liquid may
be replaced, substantially as hereinbefore described.
4. In the coupled pump hereinbefore described, the replacement of the air
dome (1) by a plunger (F) mounted in the wall of the pump chamber of the second
pump (B) and loaded by means of a spring (f), said plunger under the action of
the movement of the pump plungers acting to expand or compress the spring (f)
and thereby producing a very gradual increase of the liquid pressure in the pump
chambers from a minimum to a maximum or vice versa, substantially as herein-
before described.
T1 L 001 1900