Abstrict
A filter cloth securing device attaches a filter cloth in the zone
of the slurry port of a filter plate. A plurality of face-to-face
arranged filter plates constitute a filter plate stack of a plate
filter press. Each filter cloth securing device has two flanged
sleeves inserted from either side of the slurry port and a threaded
tightening sleeve which passes through the slurry port and which
tightens the flanged sleeves to one another to thus clamp the filter
cloth against the filter plate face. In the closed state of the
filter plate stack face-to-face oriented flanged sleeves belonging
to consecutive filter plates define an annular clearance and further,
at least one flanged sleeve of the filter cloth securing device
has on its outer face at least one protuberance which projects towards
the outer flange face of an adjoining flanged sleeve, belonging
to a consecutive filter plate. The protuberance ends at a distance
from the last-named outer flange face.
Claims
What is claimed is:
1. In a filter press including a filter plate stack formed of a
plurality of face-to-face arranged filter plates each having a central
plane and peripheral sealing faces being in a mutually contacting
sealing relationship in a closed state of the filter plate stack;
adjoining filter plates together defining a peripherally sealed
filter chamber; each filter plate having a slurry port from which
liquid to be filtered is adapted to flow into respective said chambers;
each slurry port having an axis; a filter cloth extending in each
chamber along a face of each filter plate; and a filter cloth securing
device arranged for clamping the filter cloth against an annular
zone of said face of a respective said filter plate; said annular
zone surrounding said slurry port; said filter cloth securing device
including two flanged sleeves inserted into said slurry port from
opposite sides thereof and a threaded tightening sleeve coaxially
passing through said slurry port and threadedly engaging said flanged
sleeves for tightening said flanged sleeves toward one another;
each said flanged sleeve having a flange having first and second
flange faces extending generally parallel to said central plane;
said first flange face being oriented toward the central plane of
an associated said filter plate and being arranged to clamp the
filter cloth against the associated filter plate in said annular
zone; said second flange face being oriented away from the central
plane of the associated filter plate; the improvement wherein face-to-face
oriented said second flange faces of adjoining flanged sleeves belonging
to two consecutive filter plates of the filter plate stack together
define, in the closed state of the filter plate stack, an annular
clearance between axially aligned slurry ports belonging to said
consecutive filter plates; and further wherein at least one said
flanged sleeve of each said filter cloth securing device has at
least one protuberance extending from the second flange face of
said at least one flanged sleeve; said protuberance extending towards
the second flange face of an adjoining said flanged sleeve belonging
to a consecutive said filter plate; said protuberance remaining
out of contact with said second flange face of said adjoining said
flanged sleeve in the closed state of said filter plate stack; said
protuberance having a height measured parallel to the axis of said
slurry port; said height being less than said width of said annular
clearance.
2. A filter press as defined in claim 1, wherein said annular clearance
defines a first cross-sectional flow passage area and said slurry
port has an inner diameter d.sub.1 and defines a second, free cross-sectional
flow passage area; further wherein said first cross-sectional flow
passage area, related to said inner diameter is smaller than said
second, free cross-sectional flow passage area.
3. A filter press as defined in claim 2, wherein said annular clearance
has a width S.sub.1 measured parallel to the axis of said slurry
port; said width having a magnitude between 0.05d.sub.1 and 0.15d.sub.1.
4. A filter press as defined in claim 3, wherein said width is
constant as viewed in a radial direction of said annular clearance.
5. A filter press as defined in claim 3, wherein said width decreases
as viewed in a radially outward direction of said annular clearance,
from a radially inner value equalling said magnitude.
6. A filter press as defined in claim 1, wherein said height is
0.5-1.5 mm less than said width.
7. A filter press as defined in claim 1, wherein said protuberance
is present in a plurality on at least some of said second flange
faces.
8. A filter press as defined in claim 7, wherein the protuberances
projecting from at least one said second flange are two in number
and are arranged in a diametrically opposite relationship; in said
closed state of the filter plate stack the protuberances belonging
to a common said second flange face are situated in a vertical alignment.
9. A filter press as defined in claim 1, wherein said second flange
faces have a bevelled outer marginal circumferential edge zone tapering
radially outwardly towards the central plane of the associated filter
plate.
10. A filter press as defined in claim 9, wherein some of said
filter plates are first, chamber-type filter plates and some of
said filter plates are second, diaphragm chamber-type filter plates;
said first and second filter plates being arranged in an alternating
sequence in said filter plate stack; further wherein said bevelled
zone is provided on flanged sleeves belonging solely to said first
filter plates; said bevelled zone having a radially inner edge being
approximately axially adjacent to a radially outer edge of an adjoining
said second flange face of a flanged sleeve belonging to a consecutive
second filter plate.
11. A filter press as defined in claim 1, wherein the flanged sleeves
of at least some of said filter cloth securing devices have an annular
skirt surrounding the slurry port and projecting axially from said
first flange face towards and being in contact with said filter
cloth.
12. A filter press as defined in claim 11, said skirt having a
radial end face; further comprising a circumferential groove provided
in said end face and a sealing element received in said groove.
13. A filter press as defined in claim 12, wherein said sealing
element is an O-ring.
14. A filter press as defined in claim 1, wherein each annular
clearance has a first halving plane being perpendicular to the axis
of the slurry port and each filter chamber has a second halving
plane being perpendicular to the axis of the slurry port; the first
halving plane of any selected said annular clearance coinciding
with the second halving plane of the filter chamber associated with
said selected annular clearance.
Description BACKGROUND OF THE INVENTION
This invention relates to a filter cloth securing device which
attaches the filter cloth to the filter plates of a plate filter
press in the zone of the plate opening (port) provided for the passage
of the slurry. The securing device has two flanged sleeves inserted
into the slurry port from opposite sides of the filter plate and
a threaded tensioning sleeve which also passes through the slurry
port and which axially clamps the flanged sleeves to one another.
The flanges of the flanged sleeves extend essentially parallel to
the plane of the filter plate.
In chamber-type or diaphragm chamber-type filter presses where
the slurry inlet is arranged in the zone of the filtering face of
the filter plates, the filter cloth must be sealed with respect
to the edge zones of the slurry ports. Such seal is of importance
in case of individual or continuous filter cloths as well as in
case of tubular or pass-through filter cloths in order to prevent
a filtering effect and thus a filter cake formation within the slurry
channel constituted by the series of axially aligned slurry ports.
As securing and sealing means generally the earlier-noted flanged
sleeves are used whose flanges press the filter cloth against the
respective filter plate side in the wall zone of the slurry port.
In order to ensure an optimal utilization of a filter press, it
is desired that the filter cakes in all filter chambers be identically
thick. This is of particular importance in case the filter cakes
have to be washed or dried in the filter press, because only a uniform
filter cake thickness ensures a uniform washing and drying effect.
A uniform cake thickness, however, preconditions identical chamber
depths which in turn require an accurately central positioning of
the filtering face in the individual filter plates. Particularly
in filter plates made of synthetic materials, deformations of the
filtering face from the central plate plane may occur because of
stresses applied during manufacture, shipping or storage. Furthermore,
in case of hot filtering, the filtering face may undergo bulging
deformations even in case of very small pressure differences resulting,
for example, from non-uniform filter cloth soiling. Such deformations
may lead to a cracking or breakage of the filter plate.
In diaphragm-type filter presses a bending of the filtering face
and thus an increased filter chamber depth on one filter plate side
has the additional disadvantage that the diaphragm may press annularly
into the slurry channel on that side so that the diaphragm may be
torn away from its securing device or may be torn open.
In order to prevent a bending deformation of the filtering face,
U.S. Pat. No. 3,503,326 discloses the use of tubular screw-in flanges
which are threaded into corresponding passages of the filter plate
from both sides and wherein the tubular part of the components constitutes
the slurry port and the flanges sealingly clamp the filter cloth
against a cooperating counterface of the filter plate. The flanges
have such a thickness dimension that in the closed (pushed-together)
state of the filter plate stack they lie on one another and thus
are in a mutually supportive relationship. The slurry inflow in
the individual filter chambers is effected by radial grooves provided
in the outer surfaces of the flanges. In such a structure the grooves
of two superposed flanges of adjoining filter plates complement
each other to form a closed channel. It is a disadvantage of this
arrangement that the screw flanges must have an accurate angular
(screwed-in) orientation in order to position the grooves such that
in the closed state of the filter plate stack the grooves of adjoining
flanges complement each other to form a slurry channel. Considering
the permissible tolerance deviations, this requirement cannot be
satisfied with the desired accuracy.
It is a further disadvantage of the above-outlined prior art arrangement
that upon tightening the screw flanges, as a result of friction
that part of the filter cloth which lies underneath the flange faces
is dragged by the flange As a result, folds may appear which can
cause leaks between the slurry channel and the filtering spaces.
If the threaded flanges are not tightened sufficiently, the individual
filter cloth securements may abut one another in an axial direction
even before the filter plates are tightly pressed to one another
at their outer sealing edges. As a result, the filtering chambers
will not be separated from the environment in a fluidtight manner.
It is still another disadvantage of this prior art arrangement that
during the emptying process solid deposit residues may clog the
channels formed by the grooves.
A similar construction is known in the field of chamber-type filter
plates which are utilized as a combination with diaphragm-type filter
plates known from German Patent Nos. 2,322,044 and 2,324,876. In
this arrangement too, screw-in flanges are provided which are tightened
against one another by a threaded bushing and thus clamp the filter
cloth. In this arrangement too, the slurry is admitted into the
filter chamber from a slurry port formed by the threaded sleeve
and through radial grooves provided in the outer faces of the flanges.
The flanges are configured such that the diaphragms of the adjoining
diaphragm filter plates annularly lie against the flanges upon inflation
and cover the mouth of the radial grooves in the filter chamber.
This prior art arrangement too, has the disadvantage that the radial
grooves are clogged by the filter cake and also, during the pressing
step, the diaphragms additionally press filter cake portions from
the filter chamber into the radially extending grooves.
In all known structures of filter cloth securing devices solid
deposits do not detach by themselves from the radial grooves during
the opening of the filter press. Further, as the filter cake falls
down in the zone of the slurry intake, solid parts are sheared off
the filter cake and remain suspended in the slurry ports, particularly
because of the recessed end faces of the threaded sleeves. Risks
are high that these residues may block the radial grooves in the
outer faces of the flanges during the subsequent operational cycle.
Consequently, the grooves as well as the slurry ports of the individual
filter plates have to be carefully cleaned manually in each filter
chamber after opening the filter press in order to avoid any damage
during the subsequent filtering cycle. A cleaning of the slurry
ports and the radial groove is, however, not readily feasible because
of the particular configuration of the filter cloth securing devices.
Furthermore, because of a need for the manual cleaning, the advantage
of a mechanized plate shifting apparatus which should make possible
an automatic filtering operation is partially lost, and thus the
time needed for the manual cleaning work adversely affects the output
of the filter press.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an improved filter
cloth securing device of the above-outlined type which ensures a
uniform charging of all the chambers of the filter press, which
prevents the formation of solid deposits during operation and which,
during the opening of the filter press, does not allow filter cake
deposits which would require an additional cleaning input.
This object and others to become apparent as the specification
progresses, are accomplished by the invention, according to which,
briefly stated, in the closed (pushed-together) state of the filter
plates the essentially planar outer faces of the adjoining flanges
of the flange sleeves of two neighboring filter plates bound an
annular clearance and further, at least one flange is provided on
its outer face with at least one cam-like elevation (protuberance)
which is oriented towards the outer face of the adjoining flange
and which terminates at a small distance from the outer face of
the adjoining flange.
The invention as outlined above has the advantage that in the closed
state of the filter plate stack in which the axially aligned individual
slurry ports of the individual filter plates form a throughgoing
slurry channel, the slurry inflow to each individual filter chamber
occurs through a smooth, annular clearance which is interrupted
solely by the cam-like elevation. During the filtering process the
slurry flow for each filter chamber is uniform to all sides, so
that as early as from the beginning of the filtering process there
occurs a uniform solids deposition which results in the formation
of a uniform filter cake.
The smooth annular clearance provided according to the invention
further ensures that no clogging by solids may occur since the pressurized
slurry may itself rinse away any such solid deposits. The slight
interruption of the annular clearance by the cam-shaped elevation
(protuberance) has no appreciable effect. According to an advantageous
feature of the invention, only two cam-shaped elevations are provided
which are situated diametrically oppositely on the outer faces of
the respective flanges and which, related to the operational position
of the filter plates, are situated vertically below one another.
If, upon termination of the filtering phase, the filter plate stack
is opened (that is, the filter plates are moved away from one another),
the filter cake may readily slide downwardly, even over the zone
of the filter cloth securing device. Slight shearing effects caused
by the cam-shaped elevations or by the slurry ports themselves do
not adversely affect the subsequent filtering cycle, because such
deposits may be rinsed away by the slurry flow during the subsequent
filtering cycle. It is of importance that upon the subsequent closing
of the filter plate stack in the zone of the annular clearance itself
no deposits will be present. Since the zone of the filter cloth
securing devices is formed of a rigid construction, a single cam-shaped
elevation in this zone is sufficient to ensure a mutual support
of the filtering face. By virtue of the fact that the cam-like elevations
terminate at a small distance from the outer face of the flange
belonging to the adjoining filter plate, during closing of the filter
plate stack the sealing edges in the zone of the outer peripheral
edge of the filter plates may be pressed sealingly to one another
by the press closing device without interference.
According to a preferred embodiment of the invention, the width
S.sub.1 of the annular clearance (measured parallel to the axis
of slurry port) is so dimensioned that the free cross-sectional
passage area of the annular clearance related to the inner diameter
d.sub.1 of the slurry port is smaller than the free cross-sectional
passage area of the slurry port. This arrangement ensures that in
the closed state of the filter plate stack all filter chambers of
the filter press are charged uniformly with slurry. According to
an advantageous feature of the invention, the clearance width S.sub.1
is between 0.05d.sub.1 and 0.15d.sub.1. This dimensioning means
that the above-noted free cross-sectional passage area of the annular
clearance is between 20 and 60% of the free cross-sectional passage
area of the slurry port. While normally the clearance width S.sub.1
between two adjoining outer flange faces is constant in the outward
radial direction, according to a particularly advantageous feature
of the invention, the clearance width between two adjoining outer
flange faces decreases radially outwardly from a radially inner
dimension S.sub.1. Expediently, the decrease of the clearance width
is so dimensioned that the inlet cross section of the annular clearance
related to the inner diameter of the slurry port is identical to
the outlet cross section of the annular clearance in the zone of
the outer diameter of the annular clearance. As a result, the facing
outer surfaces of two flanges are slightly conically recessed towards
the slurry port so that the risks of a formation of solid deposits
during filter cake ejection are further reduced. This feature is
of particular significance in filter presses where the filter plate
stack is composed alternatingly of chamber-type filter plates and
diaphragm chamber-type filter plates, because in this manner there
is achieved a closing (separation) of the filter chamber from the
slurry channel by the diaphragm as early as during the initial phase
of the pressing step. Since, according to the invention, the central
plane of the annular clearance between two adjoining flanges lies
in the central plane of the filter chamber formed of two superposed
filter plates, there is achieved, during rinsing through the slurry
channel, a better distribution of the washing liquid in the clearance
between the two filter cake layers.
According to a further advantageous feature of the invention, the
outer flange edge of the flanged sleeves is bevelled radially outwardly
towards the central plane of the filter plate. By virtue of this
feature the outer edge of the flange functions as a deflector during
the filter cake ejection, so that the lower edge of the slurry port
does not, for all practical purposes, come into contact with the
filter cake and thus a shearing off of solid particles from the
filter cake and deposits in the slurry port are prevented.
According to a further feature of the invention, in a filter plate
stack which is formed of alternating chamber-type filter plates
and diaphragm chamber-type filter plates, the inside edge of the
bevel of the flange of the chamber-type filter plate lies approximately
opposite the outer edge of the flange of diaphragm chamber-type
filter plate. By virtue of this feature, a disturbance-free closing
of the annular clearance by the diaphragm may be achieved during
the pressing of the filter cake and, at the same time, the bevel
of the outer edge of the flange serves as a support for the diaphragm
in this zone and thus an excessive expansion of the diaphragm is
avoided.
According to a particularly advantageous further feature of the
invention, the flange, on its side oriented towards the filter cloth,
has in the zone of its outer circumference a circumferential web
(annular skirt) which projects towards the filter cloth. This arrangement
has the advantage that upon tightening together the two flanged
sleeves by the threaded clamping sleeve, the two flanges engage
the filter cloth only with the annular skirt, so that the sealing
forces between the flange and the filter cloth become effective
only along this outer annular surface. Upon tightening the two flanged
sleeves, the flanges are elastically deformed so that, for example,
in case of an axial expansion caused by a temperature increase,
there is ensured a minimum pressing force and thus a satisfactory
seal between the web and the filter cloth is maintained. Such an
arrangement is also advantageous if individual filter cloths are
used because in such a case the filter cloth edge surrounding the
slurry port may have a corresponding bead (thickening), provided,
for example, by vulcanization or sewing. The bead lies in the undercut
part of the flange, bounded by the annular skirt. The bead functions
as a seal and also, it effects a form-fitting clamping of the filter
cloth in that zone.
According to a further feature of the invention, the outer face
of the annular skirt has a circumferential, open groove which accommodates
a sealing element, such as an O-ring. This arrangement is advantageous
in that it further increases the sealing effect between the annular
skirt and the filter cloth.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a fragmentary sectional side elevational view of a closed
filter plate stack in the zone of the slurry port, illustrating
a preferred embodiment of the invention.
FIG. 2 is a fragmentary sectional side elevational view of a closed
filter plate stack, illustrating another preferred embodiment.
FIG. 3 is an enlarged sectional view of a detail of FIG. 2.
FIG. 4 is a sectional view similar to FIG. 2, illustrating another
preferred embodiment of the invention.
FIG. 5 is an enlarged sectional view of a detail of FIG. 4.
FIG. 6 is a front elevational detail of FIG. 1 viewed in the direction
of arrow A of FIG. 1.
FIG. 7 is a fragmentary sectional side elevational view of a further
preferred embodiment of the invention.
FIG. 8 is a view similar to FIG. 7, illustrating still another
preferred embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Turning now to the embodiment of the invention illustrated in FIG.
1, there are shown three filter plates 1 of a filter plate stack,
illustrated in a closed (pushed-together) position. Each filter
plate 1 is provided on both plate faces with a filter cloth 2 which
is sealingly secured to the plate face along an annular area about
a slurry port 3 by means of inserted flanged sleeves 4, 4' axially
clamped against one another by means of a threaded tightening sleeve
5. Each slurry port 3 has an axis B. The flange 6 of the flanged
sleeve 4' has on its outer face two diametrically opposite cam-like
elevations (protuberances) 7 whose height h is smaller than the
width S.sub.1 of an annular clearance 8 formed by the flanges 6
of two adjoining flanged sleeves 4, 4' belonging to two consecutive
filter plates 1. Expediently, the height h is approximately 0.5
to 1.5 mm less than the gap width S.sub.1. By virtue of this arrangement,
the filter plates may support one another in case of bending deformations
resulting from differential pressure. The arrangement also ensures
that during the closing (pushing-together) of the filter plate stack,
the sealing edges 9 at the outer periphery of the filter plates
1 may be pressed to one another in a fluidtight manner. Any two
adjoining filter plates 1 define a filter chamber 10.
Each annular gap 8 has a central plane C which lies in the central
plane D of the respective filter chamber 10, defined by the sealing
edges 9. This arrangement ensures a practically symmetrical flow
of the slurry from the slurry inlet channel formed by the aligned
slurry ports 3 into the respective filter chambers 10. Since in
the embodiment shown in FIG. 1 there are provided only two diametrically
oppositely arranged protuberances (cam-like elevations) 7 on the
outer face of the flange 6 of the flanged sleeves 4' mounted such
that in the operational position of the filter plate they are disposed
vertically underneath one another, it is readily seen that during
filter cake ejection no deposits may be formed because the elevations
7 merely score the downwardly sliding filter cake without being
able to shear off filter cake portions therefrom. This is particularly
the case for the lower zone 11 of the slurry port 3. FIG. 6 illustrates
this construction as viewed axially, that is, in the direction of
arrow A of FIG. 1. It is further of significance that the outer
edge zone of the flange 6 is formed as a bevel 12, tapering radially
outwardly in the direction of the central plane E of the respective
filter plate 1. It is the function of the bevel 12 that during ejection
of the filter cake it acts as a slide or deflector so that the cake
surface will pass at a distance from the zone 11 of the slurry port
3.
Referring once again to FIG. 6, the annular clearance 8 is--as
viewed circumferentially--only slightly interrupted by the two diametrically
opposite cam-like protuberance 7 so that no deposits may be formed
there during slurry inflow. In case filtering processes are carried
out which involve adhesive solids and they form deposits in these
zones, in the subsequent filtering step they are securely rinsed
away because the slurry which, at the beginning of the filtering
step, has a relatively high flow speed, is capable of washing away
such deposits.
The gap width S.sub.1 is so dimensioned that, according to particular
modes of application, it is between 0.05d.sub.1 and 0.15d.sub.1,
wherein d.sub.1 is the inner diameter of the threaded tightening
sleeve 5, defining the slurry port 3. By virtue of such a dimensioning,
the annular gap 8, related to the inner diameter of the slurry port
3, has a cross-sectional passage area of about 20-60% of the inner
cross-sectional passage area of the slurry port 3.
Turning to FIG. 2, there is illustrated another preferred embodiment
of the invention. In the construction illustrated in FIG. 2 the
filter chamber 10 is defined by a chamber-type filter plate 1 and
a diaphragm chamber-type filter plate 1'. In the filter plate stack
the two plate types 1 and 1' are arranged in an alternating sequence.
The structure and operation of such a filter press are conventional
and are therefore not described in further detail.
In the embodiment shown in FIG. 2, both flanged sleeves 4' belonging
to one chamber filter plate 1 carry protuberances 7, while the flanged
sleeves 13 of the filter cloth securing device belonging to the
diaphragm chamber-type filter plate 1' are void of protuberances
7 and have a smaller outer diameter than the flanges 6 of the flanged
sleeves 4' associated with the chamber-type filter plate 1 in order
to ensure a sufficient free space for the edge of the pressing diaphragm
14 extending underneath the filter cloth 2. This arrangement too,
ensures a mutual support of the filter plates in the zone of the
slurry ports in case bending stresses occur.
With particular reference to FIG. 3 which is an enlarged detail
of FIG. 2, it is seen that the bevel 12 on the flange 6 of the flanged
sleeves 4' of the chamber-type filter plate 1 is so oriented that
the radially inner edge 15 of the bevel 12 which is formed in this
zone by the edges of the elevation 7, terminates approximately at
the height of the outer edge 16 of the flanged sleeve 13 associated
with the diaphragm chamber-type filter plate 1'. This arrangement
ensures that during the performance of the pressing step in which
pressurized fluid introduced behind the diaphragm 14 shifts the
diaphragm by the pressing force into its dash-dotted position into
the filter chamber 10, first, the edge 17 of the diaphragm 14 rapidly
covers the annular clearance 8 and second, the diaphragm 14 can
be supported on the bevel 12 so that an excessive expansion of the
diaphragm 14 in its clamping zone is avoided.
Turning now to the embodiment illustrated in FIGS. 4 and 5, the
embodiment illustrated therein differs from that shown in FIGS.
2 and 3 only in that the gap width between the outer faces of two
axially adjoining flanges decreases from a radially inner maximum
value S.sub.1 radially outwardly to a radially outer minimum value
S.sub.2. The dimensions are so selected that the cross-sectional
passage area defined by the gap width S.sub.1 is approximately the
same as the radially outer cross-sectional passage area defined
by the gap width S.sub.2.
Turning now to FIG. 7, there is illustrated a further embodiment
of the flanged sleeves according to the invention. Those faces of
the flange 6 which are oriented towards the filter plate 1 are provided
with an undercut part 17' so that in each instance at the outer
edge of a flange, in the zone of its outer circumference, there
is obtained an annular circumferential skirt 18 projecting towards
the filter cloth 2. Upon tightening the two flanged sleeves 4 and
4' to one another by the tightening sleeve 5, there results an elastic
deformation of the flange 6, so that even in case of a longitudinal
expansion of the threaded tightening sleeve 5 caused, for example,
by a temperature increase, the skirt 18 remains firmly and sealingly
pressed to the filter cloth 2, thus ensuring a continuous fluidtight
condition in that zone. As an additional measure, in the face of
the skirt 18 a circumferential groove 19 may be provided which accommodates
a sealing ring, such as an O-ring 20 which is deformed upon tightening
of the flanged sleeves and ensures a seal even if, because of a
longitudinal expansion of the tightening sleeve 5 or other external
effects, the sealing force drops below a permissible minimum level
at the skirt faces proper.
Turning to the embodiment illustrated in FIG. 8, the construction
shown therein constitutes a variant of the embodiment shown in FIG.
7. According to FIG. 8, the filter cloths 2 which are separate filtering
members for each side of the filter plate 1, are provided along
their edge 21 surrounding the slurry port 3 with a circumferential
bead 22 which lies in the undercut enlargement 17'. This arrangement
ensures a form-fitting securement of the filter cloth 2, so that
during operation the filter cloth may not escape from the filter
cloth securing device. Advantageously, the bead 22 is made of an
elastic material, so that by virtue of a corresponding thickness
dimensioning there is provided the possibility of a preliminary
pressing by the flanges, as a result of which the beads 22 simultaneously
serve as sealing elements.
The present disclosure relates to subject matter contained in Federal
Republic of Germany Patent Application No. P 35 40 786.7 (filed
Nov. 16th, 1985) which is incorporated herein by reference.
It will be understood that the above description of the present
invention is susceptible to various modifications, changes and adaptations,
and the same are intended to be comprehended within the meaning
and range of equivalents of the appended claims.
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