Improvements in and relating to Filter Cloths or other similar Filtering Media.
Year: 1898

page_text: PROVISIONAL SPECIFICATION,
Improvements in and relating to Filter Cloths or other similar
Filtering Media.
I, JOHN WILLIAMSON, of 65, West Regent Street, Glasgow, in the County of
Lanark, Chemical Engineer, do hereby declare the nature of this invention to
be as follows:-
My invention has for its object the provision of means for extending, or stretch-
ing tightly the cloth or other filtering medium upon or across the face of the plates
of an ordinary filterpress, or such a filter or filterpress as described in the Specifi-
cation of my Patent, No. 21934, dated 3rd October, 1896.
For this purpose in constructing the plates aforesaid, I form projections upon
the periphery or edges of same suitable for receiving brass tightening screws, such
as are commonly adopted in some forms of filterpress.
The cloths or other filtering media employed in such cases at present are pro-
vided with metal eyelets or grummets firmly gripping the cloth and these eyelets
in turn are pulled outwards by the tightening screws, but in the case of cloth or
other textile material, the pulling of these eyelets tends to draw the warp and
weft of the cloth in one direction only and in a narrow line or zone running
from the eyelet, leaving these portions of the cloth on either side of these lines or
zones in a slack condition. It is impossible therefore by these means
to stretch every part of the cloth similarly, uniformly and tightly enough for the
purposes of such filters as require the filtering medium to be thoroughly and uni-
formly stretched.
In order to overcome this difficulty, to the corners of the cloth, or to whatever
part of the cloth is convenient to the tightening screw or screws, I attach a bar of
suitable size, strength and material, or preferably a narrow strip of wood, iron,
brass, or other metal in such a way that lines stretched between the outer corners
of each of these bars or strips will completely circumscribe every part of the surface
of the cloth. Holes are provided in the strips opposite the tightening screws, into
which and through the cloth, are inserted the usual metal eyelets or grummets,
which latter thereby hold together securely the strips mentioned and the cloth.
These strips may or may not be sewn into the cloth or otherwise attached in such a
way to allow their outer edge to exert its full stretching effect upon the cloth.
The distension of these strips of metal or wood produces a uniform distension of
the cloth or other filtering medium, using a minimum number of eyelets in the
cloth and corresponding tightening screws on the filterpress plates.
Instead of attaching the bars or strips of wood or metal to the cloth. these bars
or strips may be used apart from the cloth, in which case the bars or strips are each
provided with two or more hooks distributed suitably for attaching to eyelets fixed

page_text: in the cloth the position of these eyelets being such that lines drawn through or
between them will circumscribe every part of the surface of the cloth.
Dated this 9th day of March 1898,
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agent,
nt Vincent Street, Glasgow, Agent for the Applican
Improvements in and relating to Filter Cloths or other similar
Filtering Media.
I, JOHN WILLIAMSON, of 65, West Regent Street, Glasgow, in the County of
Lanark, Chemical Engineer, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
:-
My invention has for its object the provision of means for extending, or stretch-
ing tightly, the cloth or the filtering medium upon or across the face of the plates
of an ordinary filterpress, or such a filter or filterpress as described in the Specifi-
cation of my Patent No. 21934, dated 3rd October, 1896.
The invention is illustrated by the accompanying drawings, Figure 1 being
a front elevation of a filter cloth shewing the method of securing the stretching
strips to the cloth. Figure 2 is an elevation of part of a filter cloth shewing
another method of securing the stretching strips to the cloth and of securing the
strip to the tightening screws. Figures 3 and 4 are further modifications of the
method of securing the stretching strips to the cloth.
For this purpose in constructing the plates aforesaid, I form projections upon
the periphery or sides of same suitable for receiving tightening screws, such as are
commonly adopted in some forms of filter-press.
The cloths or other filtering media employed in such cases at present are pro-
vided with metal eyelets or grummets firmly gripping the cloth and these eyelets
in turn are pulled outwards by the tightening screws, but in the case of cloth or
other textile material, the pulling of these eyelets tends to draw the warp and
weft of the cloth in one direction only and in a narrow line or zone running
from the eyelet, leaving these portions of the cloth on either side of these
lines or zones in a slack condition. It is impossible therefore by these means
to stretch every part of the cloth similarly, uniformly and tightly enough for the
purposes of such filters as require the filtering medium to be thoroughly and
uniformly stretched.
In order to overcome this difficulty, at the corners of the cloth, or at whatever
part of the cloth is convenient to the tightening screw or screws, I place a bar b, as
shewn at a, Figure 1, of suitable size, strength and material, or preferably a
narrow strip of wood, iron, brass, or other metal in such a way that lines stretched
between the outer corners of each of these bars or strips will completely circum-
scribe every part of the surface of the cloth. Holes c are provided in the cloth, as
shewn at a Figure 1, and holes b₁ in the strips opposite the tightening screws,
which extend from the cloth in the direction shewn by the arrows, into which
holes c, b, after the cloth has been doubled over as shewn at a2, the usual metal
eyelets or grummets d are inserted, as shewn at a³, Figure 1, which latter thereby
hold together securely the strips mentioned and the cloth. These strips 6 may or

page_text: may not be sewn into the cloth or otherwise attached in such a way to allow their
outer edge to exert its full stretching effect upon the cloth.
The distension of these strips 6 of metal or wood produces a uniform distension
of the cloth or other filtering medium, using a minimum number of eyelets d
in the cloth a and corresponding tightening screws on the filter press plates.
Instead of attaching the bars or strips 6 of wood or metal to the cloth, these bars
or strips may be used apart from the cloth, as shewn at Figure 2, in which case the
bars or strips b are each provided with two or more hooks g distributed suitably
for attaching to eyelets fixed in the cloth a the position of these eyelets & being
such that lines drawn through or between them will circumbscribe every part of
the surface of the cloth. A hole h is formed in the bar 6 by which said bar is
attached to the stretching screws.
Instead of sewing or otherwise attaching the strip 6 to the cloth, a detachable
bar or rod may be inserted in a folded loop in the filter cloth as shewn at Figure 3,
and a hole formed in the cloth nearer the centre of said cloth than the strip b.
In Figure 4 the same object is attained by so folding and stitching the cloth
that the detachable bar or rod is inserted between the eyelet and the main body of
the filter cloth.
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―
As means for tightly stretching filter cloths or like filtering media the provision
of bars or strips secured to the cloths at the corners convenient to the tightening
screws so that the lines stretched between the outer corners of these bars or strips
circumscribe practically every part of the surface of the cloth substantially as
described.