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Патент USA US2382853

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Aug. 14, 1945.
Filed April 12, 1.945
A ltorney:
_ Patented aegis, 194s -
2,382,853 -
UNITED s'rATi-is
amassPATENT I orgies
‘ '
Frederick Charles Bummer and William Charles
Hubert West, Pun-?eet, England, .auignora to
Thames Board Mills Limited, Purileet, Eng
land, aBritisli company
Application April 12, 1948, Serial No; 482,818
In Great Britain February 14, 1942
2_Claims. (01. 187-139)
The. present invention relates to a pneumatic
control for a pressure device which may be used
in maintaining consistency of a viscous liquid,
or semi-liquid, or density of a liquid, that is to
say of liquids containing solid matter in solution
In many industries it is particularly desirable
to provide automatic means whereby the con
sistency of a'liquid or semi-liquid under treat
ment in an industrial process‘ can be maintained
in a ?ow box 5, the material passing over a weir
8 and ?owing out from the outlet 1 on the ?ow
box remotely situated to the weir I. the level of
the liquid due to its viscosity or density taking
up a ?ow gradient such as l. Excess liquid ?ows
away from the ?ow box 5 through an outlet H
as it passes over the, weir 9, which is usually
slightly higher than the weir 6. At two spaced
points along the ?ow gradient 8 and con
veniently carried upon the sides of the ?ow box I
are mounted a pair of standpipes I0, I I, provided
with controlling cocks l2, l3, respectively, and
For instance, in the arti?cial silk industry it
‘coupled to a common air pressure lead I4. Com
is desirable that the viscosity of the liquid pass
pressed air ted to the line M will therefore
ing through the spinning jets be maintained con
stant, and again in the paper industry it is highly 16 bubble out from the lower ends of the standpipes
l0 and II and, as the static head of stun‘ or pulp
desirable that the consistency of pulp in the
manufacture of board or paper be maintained
constant to avoid irregularity in strength or
will also differ, this diii'erence of pressure being
It is known to maintain constancy of consist 20 communicated by pipe line connections l5, It,
to a differential controller formed of intercom
ency by adding or reducing the amount of ?uid
municating vessels [8, l9, containing liquid; a
forming the medium of solution or of the ?uid
movable element 20 in one vessel being connected
carrying the suspension of solid matter, or in
by linkage ii to a lever 22 operating a throttle
other cases by increasing or decreasing the tem
perature of the ?uid stream, according to the 25 valve 23 on an air bleed port 24 of an air line 28.
The link 2! may also be connected to visual in
?ow gradient of said liquid between two spaced
dicator 26, moving over a scale 21, so that the
points in an open vessel.
degree oi’ consistency, being a factor of the ?ow
An object of the present invention is to pro
gradient 8, can be read 01! thereon.
vide a pneumatic control for controlling and
damping of such arrangements and effects for 30 As there will be a time lag equivalent to the time
taken by pulp to pass from the inlet point 29 where
preventing sudden changes in the consistency
it receives free liquid from the pipe“ to the time
or density of the ?uid stream.
when it reaches the standpipe ll, hunting would
According to the present invention the pneu
occur if the pipe 25 was directly coupled to the dia
matic control operated by an alteration in dif
phragm chamber 41. To avoid this the bleed valve
ference of ?ow gradient or density between two '
spaced points in the ?uid stream does not oper 35 23, 24, is not connected directly to the pipe 46
but indirectly through a damping device which
ate means for adding a variable amount of liquid
may conveniently be in the form of a pair of in
to said ?uid stream directly but indirectly
terconnected vessels 30“, 30°, the pipe connecting
through damping means so that the quantity of
liquid being added per unit time can only be 40 them being provided with a throttle valve 30”.
The valve 24 is connected by pipe 25 with one ves
varied at a slow rate.
sel 30" whilst the other 30“ is connected to a Bour
The invention will be more particularly de
don pressure tube ll operating a lever 32 carry- '
scribed with reference to the accompanying
ing a throttle valve 33 co-operating with a bleed
drawing, in which:
Figure 1 shows the application of the inven 45 valve 34 on the air pressure line 46.
It will be preferred to provide means to adjust
tion to the control of consistency of paper pulp
the position 01 one or both of the standpipes III,
in the manufacture of board or paper.
II along the ?ow box, for instance by providing
Figure 2 shows a modi?ed arrangement suit
a graduated scale 31 on the side of the ?ow box,
able‘ for control of the consistency of a solution.
so that the device can be adjusted to suit various
In the drawing, the invention is illustrated in
grades of material, such as paper pulp to be con
connection with apparatus for controlling the
trolled, and at the same time maintain them at
density of paper Pulp
a constant consistency as indicated upon the scale
Paper pulp, taken by way of example, is cir
21 or on a graph recorder. Once this setting is
culated by means of ‘a pump i from an inlet
adjusted to a required condition of the material
pipe 2 to an outlet pipe 3. leading to a sump 4
thickness of the board or paper web.
immediately outside these standpipes III, II, will
di?er, the pressure in these standpipes 10, II,
tarding the application of the control pressure to
consistency can then be controlled and any vari
ations will be evident upon the scale 21 or on the
graph ‘recorder. Should the device be required
to operate on a wholly di?erent material an ad-'
justment oi the settlns of scale 21 may be neces
‘ the relay pressure establishing means comprising
a pair of vessels having their upper ends respec
tively connected with the control conduit in a
manner to transmit pressure from one portion
thereoi to another portion, the lower portions of
In the modi?ed arrangement of Figure 2 more
particularly suitable to the‘control of density of
a liquid medium having matter inrsolution, the"
pressure line is connected to a pair of standpipes
said vessels containing liquid and being in com
munication through a conduit having adjustable
48, 49, one of which is .displaceable' vertically as
compared with horizontally in the case of Figure
1, when it is desired to adjust the set value of
the density it is desired to maintain constant. An
adjustment of one pipe vertically relatively to the 15
other on the scale ill provides for an adjustment
to a new value of density which it is desired to
maintain constant. It will be seen that as the
density of the ?uid increases, so will the diner
encain the static head measured by the pipes
restricting means.
2. In a pneumatic controlsystem for operating
a pressure responsive device, a control-pressure
conduit, means for establis‘hirilr a control pres
'sure in said conduit which vai'ies in accordance
with a variable ‘condition, means responsive to the
control pressure including a bleed valve and a
- Bourdon pressure tube for operating‘ the same for
establishing a relay pressure proportional to the
_ control pressure, means for retarding the applica
tion 01' the control pressure to the relay pressure
20 establishing means comprising a pair 0! vessels
having’ their upper ends respectively connected
with the control conduit in a manner to transmit
1. In a pneumatic control system for operating > pressure from one portion thereof to another por
a pressure responsive device, a control-pressure
tion, the lower portions of said vessels containing
conduit, means for establishing a control pressure 5 liquid and being in communication through a con
duit having adjustable restricting means.
in said conduit which varies in accordance with
a variable condition, meansresponsive to the con
trol pressure for establishing a relay pressure
proportional to the control pressure, means for re
I claim as my invention:
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