IMPROVEMENTS IN FILTER PRESSES
Year: 1880

page_text: "
PROVISIONAL SPECIFICATION left by the said Samuel Henry Johnson at
the Office of the Commissioners of Patents on the 5th January 1880.
SAMUEL HENRY JOHNSON, F.C.S., of Stratford, in the County of Essex.
"IMPROVEMENTS IN FILTER PRESSES."
Heretofore filter presses have been formed of a series of plates placed in juxta
position face to face, and screwed up tightly between the head and follower of a
press; projecting rims truly surfaced, either formed on the plate or separately,
maintain the plate surfaces at distances corresponding to the depths of such rims.
The plates are covered with a filtering cloth on both sides, and are also provided
with suitable ribs or channels, or else with a porous covering medium, which admits
of liquid passing away to an outlet formed in the plates outside their rims or joint
surfaces. The spaces between the cloth lined plates form cells, into which the
liquid or semi liquid material to be filtered is forced under pressure. A passage or
opening, also lined with cloth, is formed through each plate, so that there is a free
communication between the several filtering cells. When the liquid or semi liquid
material to be filtered is forced into this battery of filtering chambers or cells the
liquid is forced through the filtering cloths, and flows away by the outlets under
the joint surfaces of the plates. The solid matter is stopped back, and by a
continuance of the operation ultimately fills the cells.
Cloths have usually been fixed by me on the plates of such presses in either of
two ways; firstly, the passage of inter-communication by which the liquid arrives
to the series of cells being formed by a simple hole, generally through the centre of
each plate. A pair of cloths is used to cover each side of a plate, and these cloths
are sewn together round a central hole corresponding to the hole in the plate. It
is obvious that on folding one cloth, and passing it through the hole in the plate,
and then opening it out on the other side of the plate both surfaces will be suitably
covered, the edges of the cloths passing between the rims of the consecutive plates.
Such presses are usually arranged so as to have the plates placed in a vertical
plane for facilities of emptying, and the upper parts of the cloths therefore require
to be held up; this has hitherto been principally effected by tying the opposite

page_text: .
sides of the cloths together by means of strings passing over the top side of the
plates. It is not advantageous to employ fixed fastenings on the plates, such as
eyelets and pins or hooks or other fastenings usually employed with textile fabrics,
because, even although such fabrics may be shrunk, yet it is found that some
fabrics continue to shrink whilst in use; the disadvantage of shrinkage being
that with such fixed fastenings the cloth is drawn so as to form creases running
down from the points of attachment to the central hole in the plates.
In order to avoid this inconvenience, which occasions leaks in the joints, and a
rapid destruction of the cloth at the creases, I provide the chambers with hooks,
eyes, or other fastenings for the cloths, made adjustable to the shrinkage; and this
may be done by means of a screw, a rack and pinion, a rack with spring or other
pawl, or any other contrivance, such as a collar and binding screw carrying the
hooks, and sliding on a fixed pin on the plates placed in the direction of the line
of shrinkage toward the centre hole; the essential feature of this improvement
being the provision of an adjustable fastening for the cloths compensating for
shrinkage.
A second method of fastening cloths on filter plates with a central or other hole
has been to hang the cloth in one piece over the top of the chamber, so as to cover
each side of the plate, such cloth having been previously shrunk as much as
possible. The cloth is provided with two holes, so placed that when the cloth is
hung across the plate in the way described the holes in the cloth shall as nearly as
practicable coincide with the hole in the plate. A short pipe or collar provided
with an external flange on one end, and screwed externally for a flanged nut at
the other, is then passed through the two holes in the cloth and the plate
simultaneously, and the flanged nut is then screwed on, so as to clip the cloth on
both sides of the plates round the central hole between the flanges on the collar
and nut and the intervening plate. Enough space must, when such means are
used for obtaining a light joint, be left between the consecutive flanged collars and
nuts in each 'filtering chamber or cell to admit of the fluid or semi-fluid material
under operation finding its way into the chamber with facility. Now this system
is troublesome, and is open to serious objections, occasioning leaks in the arrange-
ment in consequence of the formation of creases in the cloth by the turning friction
of the flanged nut when being screwed up.
For the flanged nut and collar I substitute a collar or tube provided with two
external flanges, and with openings through the walls of the tube between the
flanges; the tube is also made to project beyond one of the flanges for a distance
the
nearly equal to the thickness of the plate where the hole before referred to is;
distance between the two outside surfaces of the flanges is made equal to that of
the space between the consecutive plates. The cloths are hung over the top of the
plates, as with the flanged nut and collar arrangement. I then pass the projecting
tubular portion of one of the double flanged collars or tubes into the hole in the
first plate, and through the hole in the cloth which covers this plate; the tube fits
the hole in the plate, and is so beld in place. I then push the next plate, with its
cloth hanging on and the holes in the cloth coinciding with that in the plate,
against the second projecting flange of the double flanged collar, which thus clips
the cloth round the hole against the faces of this chamber, so closing the cloths up
to the plate diaphragms in one chamber. Another collar is then taken, and I
proceed to insert the projecting tube of another double flanged collar through the
cloth and into the other side of the plate last mentioned, and so on throughout
the series.
I thus form the joints of the cloths round the feed holes of the plates, and at the
same time efficiently stay the series of plates in the centre, so that on being screwed
up the system is much stronger, and is capable of being worked at higher pressures
than heretofore, besides saving considerable time in the manipulation of the cloths
on the filter press.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Samuel Henry Johnson in the Great Seal Patent Office on the
5th July 1880.
SAMUEL HENRY JOHNSON, F.C.S., of Stratford, in the County of Essex.
"IMPROVEMENTS IN FILTER PRESSES."
Heretofore filter presses have been formed of a series of plates placed in juxta-
position face to face, and screwed up tightly between the head and follower of a
press; projecting rims truly surfaced, either formed on the plate or separately,
maintain the plate surfaces at distances corresponding to the depths of such rims.
Figures 1 and 2 of the annexed Drawings represent such filter presses. In
Figure 1 the plates are rectangular, but the plates of the press represented by
Figure 2 are circular. The plates are covered with a filtering cloth on both sides,
and are also provided with suitable ribs or channels, or else with a porous
covering medium, which admits of liquid passing away to an outlet formed in
the plates outside these rims or joint surfaces. The spaces between the cloth lined
plates form cells, into which the liquid or semi-liquid material to be filtered is
forced under pressure.
A passage or opening, also lined with cloth, is formed
through each plate, so that there is a free communication between the several
filtering cells.
When the liquid or semi-liquid material to be filtered is forced into this battery
of filtering chambers or cells the liquid is forced through the filtering cloths, and
flows away by the outlets under the joint surfaces of the plates. The solid
matter is stopped back, and by a continuance of the operation ultimately fills
the cells.
Cloths have usually been fixed by me on the plates of such presses in either of
two ways; firstly, the passage of inter communication by which the liquid arrives
to the series of cells, being formed by a simple hole, generally through the centre
of each plate. A pair of clothis is used to cover each side of a plate, and these
cloths are sewn together round a central hole corresponding to the hole in the
plate. It is obvious that on folding one cloth and passing it through the hole in
the plate, and then opening it out on the other side of the plate both surfaces will
be suitably covered, the edges of the cloths passing between the rims of the
consecutive plates. Such presses are usually arranged so as to have the plates
placed in a vertical plane for facilities of emptying, and the upper parts of the
cloths therefore require to be held up; this has hitherto been principally effected
by tying the opposite sides of the cloths together by means of strings passing over
the top side of the plates. It is not advantageous to employ fixed fastenings on
the plates, such as eyelets and pins or hooks or other fastenings usually employed
with textile fabric, because, even although such fabrics may be shrunk, yet it is
found that some fabrics continue to shrink whilst in use; the disadvantage of
shrinkage being that with such fixed fastenings the cloth is drawn so as to form
creases running down from the points of attachment to the central hole in the
plates.
In order to avoid this inconvenience, which occasions leaks in the joints and a
rapid destruction of the cloth at the creases, I provide the chambers with hooks,
eyes, or other fastenings for the cloths made adjustable to the shrinkage, and this
may be done by means of a screw, a rack and pinion, a rack with spring or other
pawl, or any other contrivance, such as a collar and binding screw carrying the
hooks, and sliding on a fixed pin on the plates placed in the direction of the line of
shrinkage toward the centre hole; the essential feature of this improvement

page_text: being the provision of an adjustable fastening for the cloths compensating for
shrinkage.
Figure 3 shows to a larger scale a front view of the upper part of one of the
plates belonging to the press shown by Figure 1. a, a, a, are the hooks; they are
adjustable by means of screws; b is the cloth hanging from the hooks; a portion
only of the cloth is shown. The hooks take into eyelets near the upper edge of
the cloth. Figure 4 shows to another scale a complete plate, but without the
cloth, and Figure 5 shows (again to another scale) the plate with the cloth upon it.
A second method of fastening cloths on filter plates with a central or other hole
has been to hang the cloth in one piece over the top of the chamber, so as to cover
each side of the plate, such cloth having been previously shrunk as much as
possible. The cloth is provided with two holes so placed that when the cloth is
hung across the plate in the way described the holes in the cloth shall as nearly as
practicable coincide with the hole in the plate. A short pipe or collar provided
with an external flange on one end, and screwed externally for a flanged nut
at the other, is then passed through the two holes in the cloth and the plate
simultaneously, and the flanged nut is then screwed on so as to clip the cloth on
both sides of the plate round the central hole between the flanges on the collar and
nut and the intervening plate. Enough space must when such means are used for
obtaining a tight joint be left between the consecutive flanged collars and nuts in
each filtering chamber or cell to admit of the fluid or semi-fluid material under
operation finding its way into the chamber with facility. Now this system is
troublesome, and is open to serious objections, occasioning leaks in the arrangement
in consequence of the formation of creases in the cloth by the turning friction of
the flanged nut when being screwed up.
For the flanged nut and collar I substitute a collar or tube provided with two
external flanges, and with openings through the walls of the tube between the
flanges. The tube is also made to project beyond one of the flanges for a distance
nearly equal to the thickness of the plate where the hole before referred to is. The
distance between the two outside surfaces of the flanges is made equal to that of:
the space between the consecutive plates. The cloths are hung over the top of the
plates, as with the flanged nut and collar arrangement; I then pass the projecting
tubular portion of one of the double flanged collars or tubes into the hole in the
first plate, and through the hole in the cloth which covers this plate; this tube
fits the hole in the plate and is so held in place. I then push the next plate with:
its cloth hanging on and the holes in the cloth coinciding with that in the plate,
against the second projecting flange of the double flanged collar, which thus clips
the cloth round the hole against the faces of this chamber, so closing the cloth up
to the plate diaphragms in one chamber. Another collar is then taken, and I
proceed to insert the projecting tube of another double flanged collar through the
cloth and into the other side of the plate last mentioned, and so on throughout
the series.
I thus form the joints of the cloths round the feed holes of the plates, and at
the same time efficiently stay the series of plates in the centre, so that on being
screwed up the system is much stronger, and is capable of being worked at higher
pressures than heretofore, besides saving considerable time in the manipulation of
the cloths on the filter press.
This improvement is illustrated by the Figures 6 and 7; Figure 6 shows a front
view of one of the plates belonging to the press represented by Figure 2.
Figure 7 is drawn to a larger scale, and shows a transverse section through the
central parts of three of these plates with three flanged connecting tubes in place
between and alternately with them; c, c, c, are the plates, and d, d, d, are the
flanged connecting tubes. The filtering cloths are nipped between the surfaces of
the plates around the central holes and the flanges upon the tubes d. The
perforations in the tubes admit of the free passage of the material to be filtered
between the filtering plates.

page_text: Having thus described the nature of my said Invention and the manner of
performing the same, I would have it understood that I claim my improvements in
filter presses, substantially as described.
In witness whereof, I, the said Samuel Henry Johnson, have hereunto set
my hand and seal, this Fifth day of July, in the year of our Lord One
thousand eight bundred and eighty.
SAM. H. JOHNSON. (L.&.)