Improvements in or connected with Filtering Material for the Collection of Dust, Soot, and the like.
Year: 1893

page_text: Date claimed for Patent under Sect. 103 of Act,
being date of first Foreign Application (in 16th June, 1892
Switzerland),
Date of Application (in United Kingdom), 6th Jan., 1893
Complete Specification Left, 6th Jan., 1893-Accepted, 13th May, 1893
COMPLETE SPECIFICATION.
Improvements in or connected with Filtering Material for the
Collection of Dust, Soot, and the like.
I, LOUIS BENOIT FIECHTER of 72, Leinenstrasse, Basle in the Republic of
Switzerland, 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 :-
This invention relates to a process of collecting dust, soot and the like when
suspended in air or other fluid and in filtering material for dust collecting
apparatus, dust or stive rooms, soot or smoke catchers or other installations or
machinery in which air, steam or gas or other fluid filters are used. Flannel or
such textiles with meshes, which, owing to their porosity, are adapted for filtering
purposes, have the disadvantage that their pores and meshes become clogged up
very quickly, whereby the given filtering surface becomes reduced, and therefore
the capacity of the said installations and apparatus in which such textiles are used
is considerably lessened.
Dust collecting apparatus, smoke or soot contrivances are connected with various
ventilators by means of tubes, pipes, trunks, channels, chimneys, etcetera, and the
dust or smoke laden air coming from the ventilators must pass through the filters
to be filtered or purified. Now, if the given filtering surface be reduced owing to
the said clogging up of the pores or meshes, it follows, as a natural consequence,
that the suction power of the ventilator or ventilators must be proportionately
weakened, which forms a considerable economical disadvantage, for instance, when
applied to the cleaning of wheat, the purification of middlings, semolina and such
materials, while the air, instead of leaving the filter free and open, is compressed;"
whereby danger of explosion of combustible bodies, such as wheat, flour, coal dust,
etcetera, is created. The many attempts to keep such filtering materials open have
failed; dust chambers either covered with filtering material or their walls con-
sisting of porous material or dust collecting apparatus and such like can only then
be of use when the filtering cloth or material can be cleaned, in order to
give the air currents free exit, while at the same time the filter must be fine
enough to arrest the fine dust. The partial clearing of the pores and meshes can
only be done by means of frequent and violent brushing, knocking and shaking, by
which operations the cloth or filtering material will rapidly wear out.
The principal object of my invention is an improved filtering material made with
the warp threads only, which, at regular distances, are interwoven with the weft
threads, thus forming narrow close woven bands to keep the warp threads, which
really form the filtering medium, in their places. The warp threads, which are not
thus interwoven, are placed as close together as possible, and the more numerous
the layers of this material placed one over the other, the greater the filtering
capacity; at the same time, a sufficient filtering surface is provided by the proper
use of the filtering material, that is, when it is used in such a manner that the

page_text: addition of the various layers required for arresting fine and smoky dust shall not
obstruct the air current which is to pass through the filter.
Referring to the accompanying drawing
Figures 1 and 2 are representations of my fabric or filtering material in which
the weft threads between the two ends of the material remain free or not
intertwined or interwoven, Figure 1 showing the fabric loose; Figure 2, tight.
Figures 3, 4 and 5 show variations illustrating, on a smaller scale, a longer
length of the material. For dust collecting purposes, the distance between the
cross weavings is preferably about 5 inches, but it may be less or more to suit the
circumstances of the case. The woven bands are made wide enough at the ends to
securely attach the material say inch to 1 inch at intermediate points they need
only be inch or so.
Figures 6 and 7 are representations of my fabric or filtering material as applied,
in which the weft threads between the two ends or selvedges are intertwined or
interwoven several times, and which filtering material is wrapped round rings or
rolled up to obtain the required thickness, whereby the smoky or dusty air can pass
through from the in or outside.
It is obvious that either the weft or the warp can be intermittent, the other being
uniform.
For purposes of filtering, my filtering material can be used in a natural, loose
(Figures 1,5) or in an artificially stretched state (Figures 2, 3, 4). When it is
stretched or in any other manner tightened, it obtains greater density. The stuff
can be of service in its natural and loose state in various ways of arrangement. It
can be fixed either on frames or on perforated walls, or it can be useful in a
lying, suspending or hanging position. It can also be wrapped round perforated
cylinders, pipes, tubes, boxes, cases, rings and such like. This varied arrangement
for the fixing of the filter cloths is adopted with other filtering material, and the
fixing of my fabric in the one or other way has nothing whatever to do with the
advantages of my interrupted interweavings of weft and warp or warp and weft.
The dust particles which have remained hanging on the threads can easily be
detached by means of a slight shaking of the filtering material, or of the frames,
rings, etcetera, on which it is fixed; or the volume of dust, which has remained
hanging on the filter, will detach itself as soon as it has attained a certain
gravity.
When used for purposes of dust or smoke collection, this filtering material
cannot clog itself up, provided the threads are kept of sufficient length, between
the ends A and between the interweavings B, so that they can open themselves
when the shaking takes place, or that they refuse support to the dust or soot
particles, which have remained hanging, through the relaxation of threads from a
somewhat stretched position.
In my fabric or filtering material, the not intertwined or not interwoven filter
surfaces are either weft or warp threads, and I prefer a tight intertwined kind of
weaving or web for the ends (selvedges or lisières A) and for the interweavings B
to a loose or lax one, so as to secure the required support to the not interwoven or
intertwined threads.
It will be obvious that, if the two ends of the cloth be stretched on a frame and
these ends be alternately brought nearer together and then stretched apart, the
cloth will be violently shaken and all the loose material caught among the threads
will be immediately, shaken out.
I am aware that ordinary cloth filters have long been shaken in this way, and
indeed that it is a favourite method of shaking to stretch them tight by spring
pressure and then alternately slacken them against the pressure of the springs and
let them free, when they fly back to the tight position and thus shake off the
dust, and I make no claim for this method of shaking broadly; but, when the
cloth is formed in the manner above described, a new industrial effect is obtained,
the meshes of the cloth, which in other cases are practically squares and always
remain squares of uniform size, with my cloth open out and assume different

page_text: shapes and wide holes instead of long narrow slits, thus allowing the dust easily to
fall out.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. A filtering material or web so arranged that the weft and warp threads only
form an interweaving, intertwisting or intertwining at places, when the not inter-
twined or interwoven threads of the warp or weft form the filter surfaces, and when
these threads are long enough to effect, by means of the shaking received or by
relaxation, a loosening, a shaking or throwing off of the dust or soot that remains
hanging on them.
2. A filtering material consisting of several layers of parallel threads, each
layer being cross woven only at intervals a considerable distance apart, substantially
as and for the purposes described.
3. The process of filtration which consists in forming a filtering material of
stretched parallel threads without interweaving for considerable distances, and,
when it is required to be cleaned, alternately relaxing and stretching the threads,
substantially as described.
Dated this 3rd day of January 1893.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.