Improvements in Mechanical Filters."
Year: 1896

page_text: Date of Application, 19th Dec., 1896-Accepted, 18th Dec., 1897
COMPLETE SPECIFICATION.
"Improvements in Mechanical Filters."
I, ISAAC SHIMWELL MCDOUGALL, of High Bank, Didsbury, in the County of
Lancaster, Manufacturer, 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 mechanical filters in which the separation of suspended
or precipitated impurities in the liquid is effected by passing the liquid through
any material having sufficiently fine interstices or passages such as coke, sand,
cork, or felted or textile fabrics.
My invention is also applicable to cases where soluble or fluid impurities such
as fatty acids or lime and other metallic salts after having been precipitated by
chemical or other means are held suspended in the liquid.
My invention partly consists in an arrangement of mechanism whereby
rapidity of charging and discharging the filter is secured, and further in a special
construction of the filter so designed that the filtering medium is held in com-
pression.
My object in so compressing is to secure an equal resistance to the flow of the
liquid being filtered throughout all the interstices of the filtering medium.
Referring to the accompnaying sheet of drawing.
The figure is a sectional elevation of my improved filter.
In carrying my invention into effect according to one modification, as illus-
trated in the drawing, I construct a cylinder such as A of cast or wrought metal.
On the top of cylinder A is a cover B which carries a screw spindle C working
through a nut fixed to it, having at its lower end the sieve plate D. Immediately
underneath the cover B and on the cylinder are two pipes E and F, of which E
is a charging hand hole closed by a flange, and F is the outlet pipe.
On the bottom of the cylinder AI fix a cover G which has the inlet pipe H
attached to it, and fitted on a branch of this pipe is a mud tap I.
At the bottom of the cylinder A and between the cover H and the cylinder is
situated a large sieve plate K.
In operating my improved filter the cylinder A is completely filled with finely
granulated coke, and by means of the screw C acting upon the sieve plate D the
coke is compressed tightly in the cylinder between the sieve plate D and the sieve
plate K.
I preferably use coke, but any other filtering medium may be employed.
To the pipe H the water supply to be filtered is coupled up.
The water first passes through the. sieve plate K, and gradually rises through
the coke, passes through the sieve plate D, and finally discharges at pipe F in.a
clear or filtered state.
On the supply pipe H I usually place a safety gauge such as L, so that the
ise of pressure due to clogging up of the filter may be noted.
When I desire to clean the filter I usually connect up the pipe F at the top of
he filter, and mud cock I at the bottom to steam supply, and at the required
noment I cause steam to travel through the filter from F to I, or in the reverse

page_text: direction from I to F, for the purpose of cleansing the filter, taking care to cut
off the water supply pipe H and delivery pipe F previously.
To enable me to keep up the flow of water when the filter. is being cleansed
I provide the three valves M M M and the connecting pipes.
When I desire the water to pass through the filter I close the valve M¹ and
open the valves M M³, and when I wish the water to pass without entering the
filter I open the valve M' and close the valves M M². The water then passes along
the pipes N in the direction of the arrows...
When the filtering medium is exhausted, and it becomes necessary to remove it
and substitute fresh material, this may be rapidly done by lifting the sieve
plate by the screw C till it passes up above the aperture E in the side. The
cover is then removed from the charging hand hole E. Then the discharging
hand hole O is opened at the bottom, and the material is removed from below and
replaced from above.
The construction of the two sieve plates D and K is clearly shown in the figure.
Two stout cast iron or metal plates with perforations, carry between them a gauze
disc or discs, the plates acting as a support to the gauze in whichever direction
the pressure takes place within the filter.
It is to be distinctly understood that I do not limit myself to the filtering
medium already described, but I may use any other medium capable of distribut-
ing itself evenly under pressure.
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 :-
1. In mechanical filters in which a granular, porous, fibrous or felted material
is employed, the application of a travelling sieve plate to give pressure to the
filtering medium so that it may be held in compression and equally distributed,
and offer equal resistance throughout its mass to the passage of the liquid' being
filtered, substantially as described
i
2. In mechanical filters in which a finely granulated filtering medium is
employed, the mechanical arrangement for discharging the spent medium, and
re-filling with fresh material in an expeditious manner as herein before described
and illustrated on the accompanying drawing.
3. The construction and arrangement of mechanical filters as hereinbeforò
described, with reference to the drawing.
Dated this 10th day of December 1896.
MARKS & CLERK,
18 Southampton Buildings, London, W.C. and
13 Temple Street, Birmingham. Agents for the Applicant.