IMPROVEMENTS IN THE MODE OF CLEANING THE FILTERING MEDIA OF FILTERS
Year: 1883

page_text: LETTERS PATENT to John Eliot Hodgkin of Queen Victoria Street in the
City of London Mechanical Engineer and Edward Perrett of Victoria
Chambers in the City of Westminster Civil Engineer. for an Invention of
"IMPROVEMENTS IN THE MODE OF CLEANING THE FILTERING MEDIA OF
FILTERS."
PROVISIONAL SPECIFICATION left by the said John Eliot Hodgkin and
Edward Perrett at the Office of the Commissioners of Patents on the
24th April 1883.
JOHN ELIOT HODGKIN of Queen Victoria Street in the City of London
Mechanical Engineer and EDWARD PERRETT of Victoria Chambers in the City of
Westminster Civil Engineer "IMPROVEMENTS IN THE MODE OF CLEANING THE
FILTERING MEDIA OF FILTERS"
Our Invention relates to a mode of cleaning the filtering media or materials
(such as sand charcoal and the like) of Filters which have become choked or dirty
by the passage of the liquid to be filtered through such material, and consists in
effecting the cleansing of the dirty material by passing through it whilst covered
with water currents of elastic fluid either continuously or intermittently preferably
air thereby disturbing the material and loosening the dirt which is carried away
by a current of water supplied for that purpose.
In some cases a body of water may be circulated by a centrifugal or other pump
through the filtering material in conjunction with a current or currents of air or
elastic fluid.
.
Where a reciprocating or a plunger pump or a displacer is used to give motion
to a body of water through the filtering medium or material for the purpose of
cleaning the same the action of the pump itself can be made to draw in air which
is discharged and forced through the filtering material along with the water at
every stroke. Or the air or other elastic fluid may be admitted under pressure as
required.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Eliot Hodgkin and Edward Perrett in the Great Seal Patent
Office on the 22nd October 1883.
JOHN ELIOT HODGKIN of Queen Victoria Street in the City of London
Mechanical Engineer and EDWARD PERRETT of Victoria Chambers in the City of
Westminster Civil Engineer "IMPROVEMENTS IN THE MODE OF CLEANING THE
FILTERING MEDIA OF FILTERS
"
Our said invention relates to a mode of cleaning the filtering media or materials
(such as sand charcoal or the like) of filters which have become choked or dirty
by the passage of the liquid during filtration through such material and consists
essentially in effecting the cleansing of the dirty material by causing currents of
air or other elastic fluid to be passed either continuously or intermittently through
the said filtering medium whilst it is covered with water thereby disturbing the
filtering material and loosening the dirt which is carried away by a current of
water supplied for that purpose from any convenient source. Our said invention
may be carried out in various ways for example the air or other elastic fluid may
be introduced by means of an air pump attached to or placed at any convenient
distance from the filter to be cleaned and connected directly therewith by a pipe
or air duct or connected with a range of filters by suitable branch pipes and cocks
so as to enable any one or more of the filters of the range to be cleaned as
desired or the air or elastic fluid may be simply admitted under pressure into the.
bottom of the filter by a pipe or pipes from a coinpressed air receiver or otherwise-
or it may be forced into the filter by the action of an inducing jet of water or by the
action of the momentum of a descending column of liquid. Moreover in those cases
where a reciprocating or a plunger pump or displacer is employed for giving
motion to a body of water through the filtering medium for the purpose of cleaning
the same the air or other elastic fluid may be introduced by the action of the
pump or displacer itself which by the addition of an air inlet valve can be made
to draw in air at each stroke. Or the disturbing current or currents of air or
other elastie fluid may if desired be passed through the filtering medium in
conjunction with a body of water caused to circulate through the filtering material
by the action of a centrifugal or other pump.
And in order that our said invention may be fully understood we shall now
proceed more particularly to describe the same and for that purpose shall refer to
the several figures on the explanatory sheets of drawings hereunto. annexed
illustrating various modes of carrying out our invention the same letters of
reference indicating corresponding parts in all the figures..
Figure 1 of our drawings is a vertical section and Figure 2 a corresponding plan
of a filter wherein the aforesaid disturbing current or currents of air or other
elastic fluid is or are intermittently forced through the filtering material by means
of an air pump.
a is the body of the filter, b the filtering material (consisting of
sand charcoal or the like) supported on the perforated plate or wire gauze sheet o
and in some cases if found desirable a similar perforated plate or wire gauze sheet d
may be placed a little distance above the filtering material. e-is the supply pipe
for the air or other elastic fluid opening into the bottom of the filter by an expanded
mouth funderneath a perforated distributing plate g and communicating with the
air pump h here shown as mounted directly upon the body of the filter and worked
by a hand lever i although the said pump may obviously be worked by power from

page_text: a crank or eccentric if preferred. k is an air inlet valve opening into the pump
barrel is a pipe for the inlet of the dirty water into the top of the filter from an
overhead tank or otherwise and m is the washout pipe these pipes communicating
with the upper part of the filter through a two way or other suitable cock or
valve n.
o is the outlet pipe and cock for the filtered water the said pipe com-
municating by preference with an overhead tank (not shown in the drawings)
above the level of the filtering material so as to keep it always covered with water.
When the filter is at work the cock or valve n is so turned or adjusted as to shut
off the washout pipe m and open the inlet pipe the clean water passing out
through the outlet pipe and cock at o and rising to the overhead tank or cistern for
its reception where used. When it is required to clean the filtering material the
cock n is so turned as to shut off for the time being the inlet pipe and open the
washout pipe m air or other elastic fluid is then forced through the filtering
material by working the air pump h thereby disturbing the said material and
allowing the impurities to be separated such impurities whilst in mechanical
suspension in the water being carried off through the washout pipe m by a current
of clean water admitted for that purpose through the the pipe o or otherwise.
Figure 3 is a vertical section and Figure 4 a corresponding sectional plan of a
filter in which the disturbing currents of air or other elastic fluid are drawn in
underneath the filtering material through an inlet valve p and perforated pipes q
and forced through the same by the alternating movements of a body of water
produced by a reciprocating or a plunger pump or displacer r in connection with
the lower part of the filter through the pipe 8.
Figure 5 is a sectional detail of another arrangement for carrying out our
invention wherein the air or other elastic fluid is induced and forced either con-
tinuously or intermittently through the filtering material by the action of a jet of
water or other liquid.
Figure 6 is a diagram showing the mode of applying the same. The pipe o and
cock o' communicate with an overhead clean water tank and open at the lower
end by a jet nozzle t into the pipe-s leading to the bottom of the filter, an air inlet
valve p being provided for admitting the air or elastic fluid which is induced by
the jet from the nozzle and forced along with the water into the filter and through
the filtering material. By alternately opening and closing the cock o' the air may
be forced in intermittently if desired.
-
Figure 7 illustrates another modification of apparatus and Figure 8 the mode of
applying the same whereby the introduction of the air or other elastic fluid is
effected intermittently by the momentum of a descending column of water in the
pipe o leading to an overhead tank. o' is a slide or other valve which is to be
alternately opened and closed by a hand lever or otherwise the air entering the
pipe & through the inlet valve p when the slide o¹ is closed and being forced into
the filter by the descending column of water when the slide is opened.
Having now described and particularly ascertained the nature of our said
invention and the manuer in which the same is or may be used or carried into
effect we would observe in conclusion that what we consider to be novel and
original and therefore claim as the invention secured to us by the hereinbefore in
part recited letters patent is :-
First. The mode of cleansing the filtering materials (such as sand charcoal or
the like) of filters by causing a current or currents of air or other elastic fluid to
be forced or to pass under pressure either intermittently or continuously through
such materials whilst covered with liquid in the filter substantially as hereinbefore
described.
Second. The application and use of a current or currents of air or other elastic
fluid in conjunction with a body of water caused to move to and fro through the
filtering medium or material by the action of a reciprocating or a plunger pump or
displacer substantially as and for the purpose herein before described.
Third. The application and use to and in the cleaning of the filtering materials

page_text: such as sand charcoal or the like of filters of a current or currents of air in con-
junction with a body of water caused to circulate through the filtering material by
the action of a centrifugal or other pump as hereinbefore described.
In witness whereof we the said John Eliot Hodgkin and Edward Perrett have
bereunto set our hands and seals this eleventh day of October in the year of
our Lord one thousand eight hundred and eighty three.