Year: 1897

page_text: I, JAMES WILSON, of 11, Grove Avenue, St. Anne's Hill, Wandsworth, in the County
of Surrey, do hereby declare the nature of this invention to be as follows:-
This invention relates to filters in which filter beds of granular material are
employed and in which such filter beds are from time to time cleansed by reversing
the flow of liquid and thereby breaking up the bed and washing the material of which
it is composed.
Such a filter is described in the Specification of my Patent dated 17th October
1895 No. 19515.
To receive the filter bed I provide a frame which by longitudinal and transverse
partitions is divided into numerous cells. These cells range side by side and are
open at the top and bottom. Each cell is divided into two parts, an upper and a
lower by a perforated plate and on these plates the granular material forming the
filter bed is laid to a depth such that it covers the tops of the cells to some
depth. The space in each cell beneath the perforated plate communicates with
one general air space extending beneath all the cells.
To wash the filter, water or liquid is admitted under a sufficient pressure to
the space beneath the cells; it compresses the air in this space and in the cells
until the air bursts through the filter bed, the air confined in each cell being
driven through that individual section of the bed which the cell contains. The
air and water cleanse the bed uniformly over its entire area.
.
Pipes are provided also to supply the washing liquid to each individual cell,
the pipes passing through the walls of the cells either above or below the
perforated plates. The liquid issues in jets from openings in the pipes and aids
in disturbing the bed of granular material.
I ensure the ventilation of the space beneath the filter bed by providing valves in
the walls which stand open whilst filtration is going on but close automatically to
adunit of the washing of the filter bed.
Above the filter bed to prevent the granular material of which the bed is composed
being carried away in the washing operation a perforated screen is provided. This
screen I make in parts which are arranged in ridge and furrow and so I obtain a freer
flow for the washing liquid than would be possible if the screen were flat.
I hinge
the parts of the screen together and to a base fraine so that the screen may be folded
to give free access to the filter bed beneath.

page_text: Improvements in Filters.
I, JAMES WILSON, of 11, Grove Avenue, St. Anne's Hill, Wandsworth, in the
County of Surrey, 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 filters in which filter beds of granular material are
employed and in which such filter beds are from time to time cleansed by reversing
the flow of liquid and thereby breaking up the bed and washing the material of
which it is composed.
Such a filter is described in the Specification No. 19515, dated 17th October
1895.
To receive the filter bed I provide a frame which by longitudinal and transverse
partitions is divided into numerous cells. These cells range side by side and are
open at the top and bottom. Each cell is divided into two parts, an upper and a
lower, by a perforated plate, and on these plates the granular material forming the
filter bed is laid to a depth such that it covers the tops of the cells to some depth.
The space in each cell beneath the perforated plate communicates with one general
air space extending beneath all the cells.
To wash the filter water or liquid is admitted under a sufficient pressure to the
space beneath the cells, it compresses the air in this space and in the cells until the
air bursts through the filter bed, the air confined in each cell being driven through
that individual section of the bed which the cell contains. The air and water cleanse
the bed uniformly over its entire area.
Pipes are provided also to supply the washing liquid to each individual cell, the
pipes passing through the walls of the cells either above or below the perforated
plates. The liquid issues in jets from openings in the pipes and aids in disturbing
the bed of granular material.
I ensure the ventilation of the space beneath the filter bed by providing valves in
the walls which stand open whilst filtration is going on but close automatically to
admit of the washing of the filter bed.
Above the filter bed to prevent the granular material of which the bed is composed
being carried away in the washing operation a perforated screen is provided.
In order also to prevent waste of water in place of closing the inlet valve to the
filter by means of the same float as that which starts the syphon for drawing off from
the top of the filter bed the water which has been used for washing it a separate float
actuated by another syphon is employed.
Figure 1 is a plan of a complete apparatus embodying these improvements. This
apparatus is of the class in which a separate supply of clean water is provided for
washing the filter. Figure 2 is a front elevation of the same. Figure 3 is a vertical
section on the line 3-3, Figure 1, a few parts at the bottom of the figure being
shown in elevation. Figure 4 is a vertical section on the line 4-4, Figure 3.
Figure 5 is a plan, and Figure 6 a vertical section, of a modified form of screen.
Clean water for washing the filter bed enters by the ball cock a into the small
cistern a¹ and flows by the valve a² into the large cistern a³ until the rise of the
float at which is connected to the valve a' by the lever a pivotted at a lowers and
closes the valve. Water then continues to enter the cistern a¹ until the ball a
rises and closes the cock a cutting off the supply, the cisterns a' and as being now
both full and remaining so until emptied as hereinafter described, as is an overflow
pipe from the cistern <<".

page_text: The impure water, sewage or other liquid to be filtered enters by the pipe b, past
the valve 61, into the small tank 62, and overflowing into the perforated trough b³, is
delivered into the perforated trough 6 from which it flows in fine streams onto the
filter bed splashing being prevented by the plate b. The water is thus nerated
before being filtered which is desirable. c is a casting consisting of two sets of
vertical plates at right angles to each other forming a number of cells open at top and
bottom. The casting c is supported all round on a flange d¹ projecting inwards at
the bottom of the vessel d. c¹ is a perforated plate resting on the top of the
casting c, aud c2 is a second casting similar to c and resting on the plate c¹.
number of parallel semi-circular perforated pipes resting on the plate c' and passing
completely across it, the casting c having semi-circular notches cut in the bottoms
of one set of its plates to allow of this.
are a
The pipes open at one end into the chamber d² which extends along the whole
length of one side of the vessel d. The filtering material c rests on the plate c¹
and pipes completely filling the cells of the casting c² and extending some way
above it.
Beneath the casting c is a sloping bottom d³ leading to the delivery pipe d* which
is provided with a valve ds. After filtration has proceeded for some time the filter bed
becomes partially choked and is no longer able to filter the water as quickly as it is
supplied by the pipe 6 and the level of the water above the filter bed therefore rises
and ultimately starts the small automatic syphone which draws water from above the
filter bed and delivers it by the pipe e¹ into the tank e. This tank contains a floate
which rising allows the valve b¹ to fall the two being connected by the bell crank
lever e, cordes, bell crank lever eo, cord e7, lever e³, and cord e°. The supply of dirty
water is therefore now cut off. The syphone being a small one. does not rapidly
draw off the water from above the filter bed and filtration proceeds thereby saving a
considerable amount of water which was wasted in the former apparatus.
After a
time however water overflows from the tank e into the tank flifting the float f¹ in
it. is a lever pivotted at fs and resting on the top of the float f', it is
connected by a rod f to the arin of the outlet valve d which is therefore now.
closed. The lever f2 is also connected by the rod and cord to the lever which is
at right angles to the lever a³ and is pivotted at f. On the cord f5 being slackened
the weight pulls down the other arm of the lever and drops the valve a³ onto the
top of the overflow pipe 8 so closing it. The movement of the lever fº also
depresses the right hand arm (Figure 4) of the lever as so lifting the valve a² off its
seat and causing a sudden rush of water from the cistern a into the cistern a³
raising the level of the water in the latter and starting the automatic syphon g which
draws the water out of the cistern a³ and delivers it by the pipe g¹ into the chamber d²
and also by a continuation g2 of the pipe g' into the space above the bottom d³.
Jets of water therefore are forced through the perforations in the pipes into the
filtering material whilst at the same time the air contained in the cells of the
casting c and the space beneath it is forced upwards through it. This air raises and
separates the particles of filtering material so that they are thoroughly washed. his
a moveable screen of wire gauze or canvas or other suitable material fixed on a frame
pivotted at h¹ and having at its top a float or floats h². This screen whilst permitting
the water to pass keeps back the filtering material. The scum and froth pass over
the top of the screen. As the water level above the filter bed rises the large syphon j
is started which delivers the water by the pipe into the tank f. Hitherto the
water delivered into the tanks es and f by the syphone has been able to escape over
the lower part of the weir but the greatly increased flow now raises the level
sufficiently to start the syphons k and L. When the cistern- u³ has emptied and the
water above the filter bed has been drawn off, the syphons k and empty the
tanks and so lowering the floats and f', opening the valves b¹ and ds and
filtration recommences. The clean water in the chamber d² pipes and the
hollow bottom d³ flows out at the filtered water delivery valve d. do is a hole to
enable the chamber d' to drain completely dry. The cisterns a¹ and a³ again fill and
everything is as before. mm are flap air valves their seats being set at a slight

page_text: angle so that they are normally open but are closed when the rush of washing water
comes. n is an air pipe connected to the pipe g¹ so that there is a constant
circulation of air below the filter bed.
In place of using a pivotted screen a fixed screen may be employed. Preferably
this is arranged so as to extend round three sides of the filter bed as shown in plan
at Figure 5 and in vertical section at Figure 6. In these figures o is a frame covered
with vertical sheets of canvas, wire gauze or the like, and p is a passage between the
screen and the sides of the vessel d for the escape of the water passing through the
screens.
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 [
claim in connection with filters in which the filtering material is cleansed from time
to time by reversing the direction of flow is :-
1. Dividing the filter bed into a number of cells substantially as described.
2. Supplying water at the bottom of the cells so that the air in them is forced up
through the filter bed substantially as described.
3. Supplying water to the cells so that each receives its own portion substantially
as described.
4. The use of perforated pipes or means by which the wash water will be distributed
so that each cell receives its due portion supplying the washing water to the cells
substantially as described.
5. The combination of the castings c and c², the perforated plate c' and the pipes c³
substantially as described.
6. Providing a moveable screen above the filtering bed controlled by a float which
allows the wash water to pass but prevents the filtering material from being carried
away substantially as described.
7. Screens substantially as described and shown in the drawings.
8. The method of supplying air to the bottom of the filter bed substantially as
described.
9. Filters substantially as described and shown in the drawings.