Improvements in Filter Films and in the Method of Making the same.
Year: 1893

page_text: Date of Application, 28th Mar., 1893—Accepted, 22nd July, 1893
COMPLETE SPECIFICATION.
Improvements in Filter Films and in the Method of Making
the same.
I, EDWARD MARTIN KNIGHT, of Brooklyn in the County of Kings and State
of New York, at present residing at 4 Warren Street New York, United States of
America, Gentleman, 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 :-
My invention relates to filters and particularly to the beds thereof, and it consists
essentially in the employment of films or thin wafer-like sheets composed wholly of
comminuted asbestos the fibres of which interlock to produce a surface pervious to
water but of sufficient density to hold back the impurities in the water that have
passed the preliminary screening point.
My invention also consists of the method of making said films whereby they are
adapted for use in filter beds.
In the accompanying drawings I have disclosed a well known form of filter and
have shown my films applied thereto, but I do not limit myself to this specific form
of filter as any other well known form may be used; the filter, films hereinafter
described being applicable to any form of portable or other filters and adapted for
insertion within the bed of the filter for effecting a thorough filtration of the water
and for holding back any impurities that have passed the preliminary screening
point.
Figure 1, is a view of a stone or other filter showing filter disks with my asbestos
films placed between them and supported by and upon the lower disk.
Figure 2, is a view of one of the films detached.
Figures 3, 4, 5 and 6 illustrate steps in a method of making the films.
The form of filter shown in Figure 1 has a filtered water chamber A from which
an outlet or draw-off a leads, and in its upper portion is a conical shaped chamber B
having sloping or inclined sides or walls adapted to form seats for the filter
disks D and E, supported one upon the other and composed of glass, stone,
earthenware, porcelain or any other suitable material covered with asbestos cloth or
not, as may be desired, and having openings made through them for the passage of
the water; the said disks having inclined edges by which they may form a tight
seat against the inclined walls of the chamber B; and said upper disk having a
handle or projection by means of which it may be placed within the unfiltered
water chamber B or removed therefrom as may be desired.
A cover C is adapted to close the upper end of the filter and has a flange or
ring e fitting within the upper end of the unfiltered water chamber so as to be
securely seated in place.
Between the disks D and E and preferably supported on the lower one is one of
my filtering films F, and to these I now draw especial attention both because of the
office of these films and the method by which they are produced. The number of
films introduced in the filter bed or between the disks D and E will depend upon
the pressure of the water, therefore, when using one or two films, if the pressure is
so great as to force some of the impurities contained in the water through the filter
bed, additional films may be added until the pressure is reduced because of the
additional resistance offered. Under ordinary pressure one film will be found
sufficient.
The films are mere wafers of tissue-like form having a close or compact
appearance and yet are strong because of the intimate interlocking of their fibres.
They are composed wholly of comminuted asbestos, made preferably in the manner
hereinafter stated, and are to be placed between the disks D and E or between open

page_text: and closed woven sheets of asbestos whereby when two or more films are placed
together and examined after the filter has been in use, they will be found to
practically unite or amalgamate to form a surface pervious to the water, but whose
fibres are so intimately crossed that even the minutest particles of impurities in
the water are held back by them and prevented from passing into the filtered water
chamber.
A very desirable method of making these films is the following: A sufficient
quantity of dry and comminuted asbestos is placed into a vessel or pan G having a
wire gauze or foraminous bottom. This vessel or pan forms a holder and is to be
submerged, partly, in a pail or tank containing water whereby the loose asbestos
fibres are held in a state of flotation. Then with a brush (see Fig. 3) or with the
finger or by other means this loose floating material is tamped to cause its particles
to adhere with the fibres running in all directions and crossing each other in every
conceivable manner. The holder or vessel G is now lifted from its tank, when the
asbestos may be further tamped (see Fig. 4) to drive out any surplus water, after
which the thin and saturated film in the bottom of the holder is transferred to a
plate or other support (see Fig. 5) by introducing the latter into the holder and
then turning the latter bottom up. The film being thus removed from the holder
is now placed upon or in a heater (see Fig. 6) and is thoroughly dried by heat,
when it is ready for use.
If the films should become foul by reason of continued use in the filter bed, they
may he readily removed by taking out the filter beds or the disks D and E and a
new film or films inserted. Being composed wholly of asbestos, the films contain
no foreign admixture, and there is nothing soluble or of a decomposing nature about
them to make the water impure or to cause a disintegration of them when in use.
They are cheaply made and comparatively inexpensive and furnish an effective
medium for filtering and removing from the water that has passed the screening
point, any sedimentary matter or impurities which it may contain.
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:
1st. As an article of manufacture a film for a filter having a thin wafer-like form,
and composed wholly of comminuted asbestos the fibres of which interlock to
produce a surface pervious to water but of sufficient density to hold back impurities
in the water.
2nd. As an article of manufacture a thin film composed wholly of comminuted
asbestos whose fibres are interlocked, said films adapted for insertion in a filter bed
to hold back impurities that have passed the preliminary screening point.
3rd. The method herein described of making films for use in filters, consisting
essentially in first, floating comminuted asbestos in water while contained in a
foraminous holder; then tamping the saturated asbestos to cause its fibres to inter-
lock; then removing the holder from the water; then expelling the surplus water
in the material by pressure; then transferring the wet films from the holder to a
support; and finally transferring the film from said support to a heater and
applying heat to evaporate the moisture and thoroughly dry the film, substantially
as berein described.
Dated this 8th day of March 1893
EDWARD MARTIN KNIGHT.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.