Improvements in Filters.
Year: 1889

page_text: Date of Application, 21st Feb., 1889
Complete Specification Left, 19th Nov., 1889-Accepted, 21st Dec., 1889
PROVISIONAL SPECIFICATION.
Improvements in Filters.
I, WILLIAM MATHER of Salford Iron Works Manchester in the County of Lancaster
Engineer do hereby declare the nature of this invention to be as follows:-
When filters are employed for treating foul waters, the interstices of the filtering
material are apt to become choked or the surface may become covered by deposit of
impurities, so that after a time the flow of the liquid becomes greatly impeded or it
may be stopped altogether. In order to provide against this, filters have been
arranged with communications such that the direction of flow of the liquid can for a
time be reversed so as to wash out the deposited impurities from the interstices of the
filtering material and so to put it in condition for operating afresh. My invention
relates to means of rendering this reversal of flow automatic, and so dispensing with
attendance for that purpose, the filter and its communications being so arranged that
when the filter becomes so far choked as to impede flow through it, the flow is for
a time automatically reversed, and, the filter being thus scoured out, is re-established
in condition for direct flow through it.
The arrangement which I adopt for this purpose may be applied either to an open
or to a closed filter, in which the liquid to be filtered is fed at the top, and the filtered
liquid flows out by perforated pipes at or near the bottom. I arrange in the feed
and delivery pipes suitable cocks or valves conn cted together. In one condition,
which is the usual working condition, of those cocks or valves, the feed passes to the
top of the filter and the delivery passes from the bottom. When the cocks or
valves are simultaneously shifted, the feed passes directly to the bottom, and the
delivery passes from the top of the filter, not to the usual delivery pipe, but to a
suitable subsidence receptacle. In order to effect the shifting of the cocks or valves,
I provide in an open filter an overflow pipe at a determined height above the
ordinary working level of the feed water, or in a closed filter I provide an escape
valve loaded to a determined pressure. When the filter becomes so choked that
the level of its feed rises to the overflow pipe or that the pressure at the top of
the filter increases sufficiently to open the escape valve, liquid passes by the overflow
pipe or by the escape valve to a tank which it charges, and this tank being on a
counterpoised lever, when it is thus charged, descends, and by its descent shifts the
cocks or valves above referred to, so that the liquid, instead of passing into the top
of the filter, now passes into the bottom, ascends through the filtering material
washing out deposited impurities and carrying them with it to the subsidence
receptacle. This reversal of flow occupies only a short time, for the counterpoised
tank, after descending and operating the cocks or valves; reaches a position where a
valve in its bottom is opened allowing its contents to escape, whereupon it is caused
by the counterpoise to reascend shifting back the cocks or valves to their ordinary
working condition. Instead of using foul water to scour out the filter as above
described, the communications may be arranged so that water already more or less
purified may be used for that purpose. For more effectually clearing out the
impurities washed up from the filtering materials, I prefer to carry them off by a
central vertical pipe having its upper inlet arranged within a trumpet shaped mouth
piece, so that the current exerts an ejector action promoting the rapid outflow of the
impurities from the surface of the filter.
Dated this 21st day of February 1889.
ABEL & IMRAY,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in Filters.
I, WILLIAM MATHER of Salford Iron Works, Manchester in the County of Lan-
caster, 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 :-
When filters are employed for treating foul waters, the interstices of the filtering
material are apt to become choked or the surface may become covered by deposit of
impurities, so that after a time the flow of the liquid becomes greatly impeded, or it
may be stopped altogether. In order to provide against this, filters have been
arranged with communications such that the direction of flow of the liquid can for a
time be reversed so as to wash out the deposited impurities from the interstices of the
filtering material, and so to put it in condition for operating afresh.
My invention relates to means of rendering this reversal of flow automatic and so
dispensing with attendance for that purpose, the filter and its communications being
so arranged that when the filter becomes so far choked as to impede flow through it,
the flow is for a time automatically reversed, and the filter being thus scoured out, is
re-established in condition for direct flow through it.
The arrangement which I adopt for this purpose may be applied either to an open
or a closed filter, in which the liquid to be filtered is fed at the top and the filtered!
liquid flows out by perforated pipes at or near the bottom. I arrange in the feed and
delivery pipes suitable cocks or valves conne ted together. In one condition, which is
the usual working condition of these cocks or valves, the feed passes to the top of the
filter and the delivery passes from the bottom.
When the cocks or valves are simultaneously shifted the feed passes directly to the
bottom, and the delivery passes from the top of the filter, not to the usual delivery
pipe, but to a suitable subsidence receptacle.
In order to effect the shifting of the cocks or valves, I provide in an open filter an
overflow pipe at a determined height above the ordinary working level of the feed
water, or in a closed filter I provide an escape valve loaded to a determined pressure.
When the filter becomes so choked that the level of its feed rises to the overflow pipe
or that the pressure at the top of the filter increases sufficiently to open the escape
valve, liquid passes by the overflow pipe or by the escape to a tank which it charges,
and this tank being on a counterpoised lever, when it is thus charged descends, and
by its descent shifts the cocks or valves above referred to, so that the liquid, instead of
passing into the top of the filter, now passes into the bottom, and ascends through the
filtering material washing deposited impurities and carrying them with it to the
subsidence receptacle.
This reversal of flow occupies only a short time for the counterpoised tank, after
descending and operating the cocks or valves, reaches a position where a valve in its
bottom is opened allowing its contents to escape, whereupon it is caused by the
counterpoise to reascend shifting back the cocks or valves to their ordinary working
condition. Instead of using foul water to scour out the filter as above described, the
communications may be arranged so that water already more or less purified may be
used for that purpose. For more effectually clearing out the impurities washed up
from the filtering materials, I prefer to carry them off by a central vertical pipe
having its upper inlet arranged within a trumpet shaped mouth piece so that the
current exerts an ejector action promoting the rapid outflow of the impurities from the
surface of the filter.
Fig. 1 of the accompanying drawings is a vertical section partly in elevation of a
self cleansing filter according to my invention.
A is the casing or vessel of the filter which is closed at the top and the bottom so
that it works under such pressure as is due to the column of supply. It is charged
to a certain height with suitable filtering material leaving a space X between the
surface of the material and the top cover. B is the pipe supplying water to be

page_text: filtered, and C is the pipe for discharging the filtered water, this pipe communi-
cating with perforated pipes D within the filter. At some distance below the surface
of the filtering material there is a set of perforated pipes E communicating with
a supply of cleansing water. A pipe F open at the top extends up the centre
of the filter nearly to the top, its upper part being situated within a conoidal
deflecting hood G. At the lower end of the pipe F is a valve casing H containing a
flexible diaphragm I arranged to close or open the mouth of the pipe F according
as the pressure under the diaphragm is greater or less than the pressure in the
pipe itself. The space under the diaphragm I communicates by a pipe K with
a loaded relief valve V whence there is a discharge into a cistern M and the
pipe K communicates by a small pipe N with the upper part of the filter. From
the valve casing H above the diaphragm I a pipe L leads to the cistern M. This
cistern M is suspended by a rod P to which are linked the levers of valves B¹ E¹ (1
governing the pipes BEC, respectively, one or all of these levers being weighted
so as to overbalance the cistern M when it is empty, but to allow it to descend when
it is filled with water.
O is a pipe provided with a cock or valve O' for connecting when desired, the
pipes E and C.
At the bottom of the cistern M there is a plug valve S suspended from a fixed
point by a chains which is slack when the cistern M is in its highest position as
shewn, but which when the cistern M descends, becomes tightened so as to unseat
the valve S.
The valves B' and C¹ being open and E¹ and O₁ closed, water fills the space ✗,
and the pressure of the water therein communicated by the pipes N and K to the
underside of the diaphragm I keeps up the diaphragm closing the pipe F. The
water passing through the filtering material is discharged by the pipes D and C.
When owing to the choking of the filter the pressure in X increases so far as
to open the loaded relief valve V there is a rush of water from the pipe K into
the cistern M causing it to descend closing the valves B and C and opening E'.
Also as the pipe N is small as compared with K the pressure under the diaphragm I.
is reduced so that it descends opening the pipe F. Water now entering by the
pipes E washes upwards the dirt lodged in the interstices of the filtering material
above the pipes E, and by the siphon action of the pipe F and the hood G the
water with suspended dirt is carried rapidly off and discharged into the cistern M
which is thus kept down notwithstanding that the plug valve S is beld open. When
this flow has continued so far that the liquid in X comes below the level of the
lower edge of the hood G, air entering the space X through an air valve Z, the
siphon action of the pipe F ceases, the cistern M becomes. emptied and reascends
closing the valve and opening B' and C¹ thus re-establishing the regular action of
the filter.
Sometimes it is desirable to scour out the filter to a lower level than that of the
pipes E. For that purpose the valve O¹ is opened and O2 is closed allowing the
Scouring water to pass through the pipes D into the filtering material.
The lever of the relief valve V is preferably connected by a chain to the cistern M
so that when the cistern M descends the relief valve becomes fully opened. The pipe F
instead of being carried down within the filter may be carried down outside as indicated
by the dotted lines F'.
Although I have shewn in the drawing my invention applied to a filter closed at
the top and adapted for working under pressure, the same apparatus is applicable to
an open topped filter, the upper part X being made so much higher as may be neces-
sary to communicate by the pipe N pressure sufficient to open the relief valve V
when the choking of the filtering material causes the column in the space X to rise a
certain height above the normal level which it occupies when there is comparatively
free passage through the filter.
The time during which the scouring action is carried on should be greater or less
according to the nature and amount of the impurities deposited in the filtering
material. This time may be regulated by the appliance shewn in Fig. 2.

page_text: From the lever of the valve V is suspended a vessel W presenting a cup a with
openings immediately under the discharge from the valve. The apertures of the
cup a may be made greater or less in area according as it is required to fill the
vessel W more or less rapidly, or the vessel may be provided with an air cock b which
can be opened more or less for the same purpose. Within the vessel W is a siphon c
by which the water is rapidly discharged from the vessel when it has reached
sufficiently high in it to start the siphon. When the valve, V is opened by the
increase of pressure in the upper part of the filter, a portion of the water discharged
by the valve enters the vessel W and this additional load, even when it is small,
overcomes the counterweight on the valve lever causing the valve V to open fully
thus reducing the pressure under the diaphragm I and bringing the scouring action
into operation as above described. This action continues until the vessel W is so far
filled as to start the action of the siphon c. When this takes place the vessel W is
rapidly emptied by the siphon and the valve V is then closed causing the diaphragm I
to rise so as to stop the scouring discharge and to restore all the parts to the condition
for filtering.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
A self cleansing filter having a supply pipe to the upper part of the filtering vessel,
a discharge pipe near its bottom and an intermediate scouring pipe all provided with
valves linked to the suspending rod of a valved cistern into which opens the dis-
charge of an adjustable relief valve subject to the pressure in, the upper part of the
vessel, operating in combination with a hood and pipe with diaphragm valve arranged
as a syphon discharge from the upper part of the vessel, substantially as and for the
purposes set forth.
Dated this 18th day of November 1889.
ABEL & IMRAY,
Agents for the Applicant.