Improvements in the Arrangement and Construction of Filtering Apparatus.
Year: 1888

page_text: TRUVIDIONAL
Improvements in the Arrangement and Construction of Filtering
Apparatus.
We FRANCIS HENRY ATKINS and WALTER GEORGE ATKINS, both of 6B Victoria
Street Westminster in the County of Middlesex Civil Engineers do hereby declare
the nature of this invention to be as follows :-
:-
This invention relates to improvements in the arrangement and construction of
filtering apparatus of the character for which we received Letters Patent dated the
18th December 1878 No. 5199.
In this apparatus a hollow shaft is arranged as described in the Specification of the
Letters Patent before referred to is perforated and made to act for a centre tube for
collecting and carrying away the filtered liquid.
On this shaft at suitable distances apart we now mount double discs or filtering
frames arranged and constructed as follows:-
These double frames (advantageously made of cast iron or of other suitable material)
are formed in circles or as parts of circles (advantageously sectors) of approximately
circular form and arranged to receive the porous filtering plates or slabs which are
cemented or otherwise suitably secured thereon or therein.
The form or shape of these filtering slabs, blocks or plates may be varied and the
framework formed to receive them of corresponding contour.
The double hollow disc or frame is secured to the hollow centre shaft by bolts or
other suitable means and also if desired the separate parts thereof may be secured to.
one another.
The form of the centre hollow tube or shaft may be circular as described in our
Specification before referred to or may be square or of other suitable shape.
These double frames. are or may be secured to the central shaft by long bolts passed
through from the outer circumference of such frames into the central shaft and one form
of fastening these is to have the inner end of the bolts headed so as to pass through a
corresponding slot in the centre shaft and then by a quarter turn of the bolt the head
is turned round so as to hold securely against the inside of the shaft.
Any suitable number of these double filtering discs arranged and constructed as
previously described may be mounted on the centre hollow shaft in a tank or chamber
of suitable dimensions and the operation is as follows;
The water or liquid to be filtered flows into the tank and percolates or filters through
either of the two external faces of the hollow filtering discs aforesaid and thus reaches
the interior of the said discs thence passing to the centre tube and so flows away to
the main or reservoir.
For the purpose of cleaning the filtering medium or material when it becomes
choked the centre shaft and discs thereon are caused to rotate at the same time a
current of air is sent back through the centre tube by any suitable arrangement of
apparatus and diffuses itself throughout the interiors of the double discs and blows
through the porous slabs aforesaid.
The filtering medium is thus cleaned in a very effectual manner the impurities or
deposits being loosened and partly removed their perfect removal being advantageously
effected by means of a series of spray pipes which direct jets of water under pressure
on the external surfaces.
Water may also be used internally to assist in cleaning if desired.
In place of the frames being made of metal as herein before described we may form
these double frames entirely of earthenware or other porous slabs cemented directly
together and bolted direct to the centre shaft through their outer circumference.
Dated this 5th day of May 1888.
A

page_text: COMPLETE SPECIFICATION.
Improvements in the Arrangement and Construction of Filtering
Apparatus.
FRANCIS HENRY ATKINS and WALTER GEORGE ATKINS both of 6B Victoria Street
Westminster and 33 Bouverie Street Fleet Street, London, England, Civil Engineers.
This invention relates to improvements in the arrangement and construction of
filtering apparatus for continuously filtering large quantities of water (such as for
town supplies) and relates to that character of filtering apparatus for which Letters
Patent were granted to Francis Henry Atkins in 1873 No. 556 and to us jointly
in 1878 No. 5199. In the former, Patent single metal frames were used for the
purpose of receiving the filtering medium and were placed in an open tank so
arranged that the said frames could be removed and afterwards cleaned by scraping
the impurities off the outer surface of the filtering medium. This arrangement of
apparatus and method of cleaning the same presented certain difficulties in practice.
In the Patent No. 5199 A.D. 1878 the filtering apparatus therein described
consists of a series of double hollow discs arranged and mounted on a hollow shaft
the whole being placed in a suitable cistern. The liquid to be purified filters
through either of the two sides or faces of the double hollow discs whence it can
only escape by means of the hollow shaft which collects and conveys it to the
outside of the cistern. Our improvements relate to that portion of the filtering
apparatus therein described which consists of discs or plates of porous stone or
porous earthenware or charcoal, coke or other suitable porous material.
Hitherto there has been considerable difficulty in forming such double hollow
discs when attempting to construct them entirely of the desired filtering medium
owing to the difficulty in moulding the various portions in the requisite forms, nor
is there sufficient strength, and our present invention is intended to obviate such
difficulties by the employment of certain frames in which the said porous plates or
filtering medium is mounted and to effect other improvements which will be herein-
after explained.
In carrying out our present invention we construct a double open circular or
polygonal frame work somewhat resembling an ordinary wheel advantageously made
of cast iron though other material or materials may be used if desired. The
periphery of this wheel-like frame is solid outwardly and there are arms somewhat
like spokes of a wheel extending from the periphery to a central boss which may
be compared to the hub of a wheel. Inside the periphery, on each side of the arms
or spokes, and also round the larger circumference of the central boss there are
two continuous parallel ribs or flanges forming ledges for the purpose of supporting
porous slabs or plates which form the filtering medium. These parallel ribs are
separated by a convenient distance so as to leave a clear hollow space between them
communicating freely with the central boss, which is hollow and has also an opening
at right angles to the two faces or sides of the frame such as is usual in the hub of a
wheel. The utility of these various parts and their arrangements are hereinafter fully
described.
The filtering medium consists of slabs or plates of porous material so shaped as to
fit into the open spaces formed on each of the two sides of the double open frame
work, rests against the continuous ribs, and is secured by cement or in other suitable
manner. All the open spaces of the framework are thus filled in with such porous
slabs which therefore form the general surfaces of the two sides of the disc and leave a
hollow space inside. Hence we term a filtering disc formed in this manner a double
hollow disc.
Several of these double hollow discs are mounted on a hollow centre shaft. The
said shaft is pierced with holes, one end of the shaft is open and the other closed.
Near the open end a shoulder or collar is formed and there is a feather extending
nearly the whole length. Where the feather terminates a thread is formed which
receives a nut and the extreme end rests on a bearing. A spur wheel is fitted on

page_text: the shaft next the shoulder, then any desired number of hollow discs are placed
on the shaft each having a slot in its boss corresponding with the feather and the
nut is then screwed on the thread. The object of the feather is that when the
shaft revolves the discs must also revolve, and the object of the nut is to force
the faces of the boss of each disc tightly against the next one thus forming a
water-tight joint round the shaft.
This shaft and the double hollow discs mounted thereon form a filter which is placed
in a tank or vessel, the closed end of the shaft resting on a bearing and the open end
fitting into a stuffing box or other suitable arrangement for discharging water from
the shaft to the outside of the tank without allowing the escape of water outside the
shaft.
In the process of filtering the impure water is admitted to the tank and surrounds
the double hollow discs and shaft. The liquid filters through the porous material
and thus reaches the inside of the double hollow discs whence it passes through the
hollow bosses and through the holes with which the shaft is pierced into the hollow
shaft itself, is discharged through the stuffing box to the outside of the tank and
led away for use. The impurities in the water are arrested by the porous material.
To facilitate the construction of the double open framework when it is intended that
the complete disc shall be of large diameter the said framework may be constructed in
two or more parts, and when of more than two the various parts take the form
approximately of sectors of a circle, each sector having suitable arms or spokes
extending from the periphery to the requisite portion of the central boss.
These arms or spokes are similar to those already described with the exception of
the two extreme ones of each sector and these are solid outwardly and have two parallel
ribs on the inside similar to those on the inside of the periphery. The said sectors
may have cross arms extending from and joining one radial arm to another, such cross
arms having two parallel ribs similar to and in connection with those already referred
to and hereinafter further described and illustrated.
Large discs of this description are fitted on a hollow centre shaft in a different
manner to the small discs already described. Each sector is bolted to the shaft
quite independently of the other sectors which make up one complete disc, and the
boss of one disc does not touch that of the next disc. The extreme radial arms
and periphery of each sector being closed outwardly, the only joint to be made is
where the boss fits against the shaft. This arrangement offers great facilities both
in the first construction and also in case of accident at any time to one of the
porous slabs when any particular sector can be easily removed and a duplicate
substituted as hereinafter described and shown in the drawings.
In other respects the shaft corresponds with the smaller one already described in
having one end open and fitting into a stuffing box or other suitable arrangement for
discharging the filtered water; it is fitted with a spur wheel, worm wheel or other
arrangement for causing it and consequently the discs secured to it to revolve when
being cleaned and the opposite extreme end is closed and rests on a bearing. There
is no feather or thread and nut.
The said periphery and arins may either be fitted with ribs in the aforesaid manner
or may have any other convenient arrangement for supporting the filtering plates so
as to leave a clear hollow space between the two sides or faces of the sector.
DESCRIPTION OF THE DRAWINGS.
Similar letters of reference indicate corresponding parts throughout.
Figure 1. shows an elevation on line 1, 1, (Figure 2) of one of the two faces or sides
of a double open circular frame work with two of the filtering slabs or plates fitted

page_text: arrangement of pipes, valves, mechanism for causing the shaft and discs to revolve
when being cleaned, and other items hereafter described.
To illustrate the construction more clearly, Figures 4 and 5 show upon a larger
scale various parts of the double hollow discs shown in Figures 1 and 2.
The periphery a is solid outwardly. There are arms 6 somewhat like spokes of a
wheel extending from the periphery to the central boss c. Inside the periphery a on
each side of the arms b and round the larger circumference of the central boss c there
are two continuous parallel ribs or flanges forming ledges d for the purpose of receiving
and supporting the filtering medium e. These parallel ribs are separated by a con-
venient distance so as to leave a hollow space f between them as shown in the sections,
Figures 2 and 5. This space f communicates freely through the passage g with the
space o formed in the hollow boss c which latter has also a central opening at right
angles to the diameter by means of which the whole framework is mounted on a hollow
centre shaft h which is pierced with holes i. The water percolates through the porous
slabs and takes the course indicated by the arrows in Figure 5.
Figures 54, 5, 5º, 5º, show other sections of framework which may be employed
if desired for receiving the porous slabs or plates, these sections being merely
equivalents.
Figure 54 shews the frame made in two rings with an outer ring shrunk on to
securely hold them. Figure 5B shows the frame work made in two parts with lugs
by which the two parts are bolted together.
Figures 5c, and 5º, show sections of different solid peripheries.
It will be obvious that we do not limit ourselves to any particular section for
framework.
Figure 6 illustrates our improved method of constructing double hollow discs upon a
larger scale than those shown in Figures 1 and 2. In this case the arms bare similar
to those shown in Figures 4 and 5 but the arms 6' are similar to the periphery being
closed outwardly and have two parallel ribs corresponding with the ribs on the
periphery and arms b. Each half is bolted separately to the centre shaft h by means
of a radial bolt a passed through the interior of the frame and the two halves for
further security may be bolted together at the lugs k. The inside of the boss and the
outside of the shaft are (6
55
turned so that a water tight joint is readily made.
Figure 7 illustrates our improved method of constructing double hollow discs
upon a still larger scale the framework consisting of four separate parts or sectors.
The periphery is of a similar form to that shewn in Figure 5. The arms bare
similar to those shown in Figure 4. with the addition that there are cross arms b
in order both to strengthen the direct radial arms and also in order that the slabs
of filtering medium need not be so large as would be the case if it had to extend
from the periphery to the central boss. The arms 6 are of similar construction
to the periphery, being closed outwardly and having parallel ribs d on the inside
corresponding with those already described.
Figure 7 is a section on line 3-3 Figure 8 showing a view of the interior face of
one of the sides of a sector of the disc Figure 7.
If desired supporting pieces 63 63 are cast or formed between the two sides of the
hollow framework to strengthen and support same.
In some cases an extra ledge (or ledges); may be used as shown in Figure 7 quite
flat on its outer surface so that one large slab as el Figure 7 may be laid right over
same or in place thereof two or more small slabs may be used and be joined over such
ledge (or ledges) į so as to make up the equivalent of the one large slab e¹ and be
secured as previously described.
Each sector is secured to the hollow centre shaft h by means of bolts a' as shown,
the heads a of these bolts being passed through the holes and a quarter turn is then
given them thus the heads a are secured to the shaft h and the whole of the sectors
firmly secured to the centre shaft, or the bolts a¹ may be screwed direct into holes
tapped to receive them in the shaft h, or they may be secured in any other suitable
manner.

page_text: sector so that a water-tight join is readily made when the sector is placed in position
and secured by means of the bolts a¹.
Figure 8 shows an edge view of our improved discs partly in section mounted in
position on the hollow centre shaft in the tank.
In this view two different modifications in the construction of the periphery of
framework are shown in section, the framework of disc marked y corresponding with
that shown in Figure 5" and the framework of disc marked z being similar to that
shown in Figure 5. each such modification showing also different supporting pieces 6*
applied thereto.
I
2
Figure 84 shows the arrangement of spray pipes m in action when cleaning the
discs as hereinafter explained.
According to the size of the filtering apparatus required any number of double
hollow discs are mounted on a hollow shaft the whole being placed in a tank into
which the water to be filtered is admitted.
Figure 9 is an exterior view in elevation of a tank fitted with our improved filtering
apparatus ready for use.
Figure 10 is a corresponding view of same apparatus with front of tank removed
and showing the gearing for revolving the shaft and discs thereon during cleaning.
Figure 11 is a side elevation of same apparatus with side of tank removed.
Figure 12 shows a plan of a range of our improved filtering apparatus corresponding
with that shown in Figures 9, 10 and 11 and indicates a convenient arrangement of
pipes and valves; for inlet for unfiltered water, outlet for filtered water and waste;
also connections for compressed air or steam.
Such a range of four filters with discs of about 7 feet in diameter is suitable for
filtering about one million gallons per 24 hours.
Figure 13 is a ground plan partly in section.
Figure 14 a longitudinal elevation partly in section, and Figure 15 is a transverse
sectional elevation, these figures 13, 14 and 15 together showing a complete plant and
the method of working same.
There is a double range of filtering apparatus, each range consisting of 8 tanks
supplied with the water, to be filtered by a conduit t.
There are also shewn steam boilers 99, engine r for rotating the discs during
cleaning, and engines for compressing the air if the latter is used in cleaning, also
reservoirs for storing a supply of compressed air. The figures also indicate a
mode of conveying motion from the engine to the respective ranges of filters, the
rotating mechanisms attached to each tank and series of double hollow discs being
indicated in a more detailed manner upon Figures 10, 11 and 12.
Convenient connections are also shown from the air compressing engines to the
compressed air reservoirs ¹¹ and thence to the compressed air or steam pipe p
extending along each range of filters and communicating as hereinafter described with
the interior of each hollow centre shaft upon which the double hollow discs are
mounted the steam being admitted to the pipe p in any convenient manner and the
compressed air shut off or dispensed with altogether. uu represent overhead travelling
cranes employed to facilitate the handling of the various sectors of filtering discs or
other parts of the apparatus. A system of tram lines is also indicated for the
conveyance of parts of the apparatus to and from a workshop for repairs, such
workshop being conveniently situated in the engine room as shown in Figure 13
or elsewhere. Such a range of our improved Filtering apparatus (with discs also of
about 7 feet in diameter) is suitable for a supply of from eight million to ten million
gallons 24 hours.
per
The designs shown for plant to deal with one million gallons and 8 to ten million
gallons respectively per 24 hours are only intended to illustrate the principle of
our improved Filtering apparatus. We do not bind ourselves to such designs
because considerable variation may be necessary according to the nature of the
water and local circumstances. This will be readily understood by everyone having
had experience in filtration...
...

page_text: In the several Figures the letter indicates the inlet admitting unfiltered water to
the tank, the letter w the outlet for filtered water, and the letter the outlet for
emptying the tank when cleaning or repairing.
n is a pipe conveying high pressure water the spray pipes m, and p is a pipe
conveying air or steam under pressure to the interior of the hollow centre shaft h and
double hollow filter discs during cleaning.
The mechanism shown in Figures 2 and 3 and also that shown in Figures 10, 11
and 12 for the purpose of rotating the hollow centre shaft and double hollow filter
discs during cleaning are merely indicated as being convenient, but other suitable
means of imparting motion to the filtering discs may be employed if so desired.
The action of our improved Filtering apparatus is as follows:-The Tank is
kept charged with water to be filtered. This percolates or filters in the direction
shown by the arrows through the porous slabs or plates which form the sides of a
double hollow disc and the impurities in the water are arrested by the said porous
slabs or plates. The filtered water inside the double hollow disc passes through
the, openings. g and. through the holes i into the hollow centre shaft is discharged
through the stuffing box to the outside of the tank and is led away for use.
The operation of cleaning the double hollow discs is as follows:-
The flow of the water (to be filtered) into the tank is stopped, and also that of the
filtered water, and such tank partly or wholly emptied. The hollow centre shaft
and the double hollow. discs mounted thereon are caused to revolve slowly as
hereinbefore described. At the same time a current of air or steam from the
pipe p is sent back through the centre shaft and diffuses itself throughout the interior
of the discs. This has the effect of driving out the water (held in the porous slabs
by capillary attraction) and this water carries with it the impurities that have been
arrested during filtration.
When the tank is emptied, the lower part of the diso contains some water and thus
as the discs revolve the porous slabs in the lower part are alternately charged with
water and this water driven out by air or steam as those porous slabs which were below
the centre shaft rise above it. This can be continued to any extent by sending back
into the centre shaft h water that has been filtered to further charge the discs at the
same time that the air or steam is being blown through them. The pressure of air or
steam required is very moderate viz. about 3 or 4 lbs. to the square inch usually
answering the purpose satisfactorily.
The removal of these impurities is completed by means of jets of water (or steam)
under pressure directed against the outer surfaces of the discs by means of small
pipes m placed between but not in contact with the discs. The employment of
steam as an alternative. to the compressed air used in cleaning will be found very
advantageous, for instance this use of steam will be found especially effective for
destroying any germs or organic matter arrested by the filtering medium.
The frequency with which it is desirable to use steam in this manner depends upon
the character and amount of the impurities contained in the water being filtered.
By means of our improved Filtering apparatus a single filter may be constructed,
possessing an area of one thousand square feet or more and may be completely aerated
or steamed cleaned and filtering resumed in less than half an hour, one man only
being necessary. Also in case of one of the porous slabs in any sector becoming
damaged such sector can be easily removed a reserve sector fitted in its place and the
filtering resumed in a very short space of time.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:
1. In filtering Apparatus the employment of a double open framework (advan-
tageously made of cast iron) to receive porous slabs, blocks or plates, the whole
forming a double hollow disc. The said frame being secured on a central hollow shaft
arranged and combined substantially in the manner and for the purposes hereinbefore
described and represented in the drawings hereunto annexed,

page_text: 2. The improved arrangement and construction of filtering apparatus substantially
in the manner and for the purposes hereinbefore described and represented in the
drawings hereunto annexed.
Dated this 5th day of March 1889.
TONGUE & BIRKBECK,
34, Southampton Buildings, London, W.C., Agents for the Patentees.