Note: Descriptions are shown in the official language in which they were submitted.
~671~
~ his i~ventioD relates to a method of, aDd apparatus
for aerating liquid stored in a settlin~ tank of a machiDe
tool system iD order to iDhibit the growth o~ anaero~ic
bacteria in that liquid, the settling tank comprising a
source from which such liquid is dr~wD for use as ~
coolant and/or a lubricant iD a machiniDg operatioD at
one or more machini~g stations of the s~stem when the
system is operatiDg and to which liquid so used is returned
after such useO
lo ~iquid stored in a machiDe tool system settling
tank can be aexated by injecting compressed air into the
liquid within the tan~ and allowing that compressed air
to bubble through the liquid, but the amount of compressed
air that is required is such that such a techDique for
aeratiDg that liquid is costl~. ~n ob~ect o~ this iDveDt-
ioD i8 to pro~ide a method of aDd apparatus for aeratiDg
liquid contained within a ~ac~ine tool s~stem settliDg
tank which does Dot require such a~ eYpensive suppl~ o~ air.
~ccording to o~e aspect Or this inveDtioD we provide
a method of aeratin~ liquid stored in a settliDg taDk of
a machiDe tool system ~omprisiDg drawing off li~uid from
tbe tank whilst tbe machine tool s~stem is shut dowD,
aerating the drawn off li~uid outside the mass of liquid
stored iD the tank and returDiDg the aerated liquid to
the mass of liguid s~ored in the tank.
~ iquid ma~ be drawD coDtiDuously from the settliDg
tank as a str2am,
-- 2 --
6'76~
aerated outside the mass of liquid stored iD the tan~ and
returDed to the mass of liquid stored iD the ta~k continu-
ously whenever the s~stem is shut down. Such a CoDtiDuous
stream of li~uid drawn from the settliDg ta~ pre~erabl~
is converted into a spray iD a region into which fresh
air flows so that tbe ~resh air and spray intermiDgle i~
that region to aerate the liquid. Preferably the stream
of liquid is converted into a spray by being directed to-
wards the apèY of coaxial tapered deflectiDg meaDs, the
lo stream striking the tapered deflectiDg means and being
deflected thereby to form a substaDtially circumfereDtially
contiDuous radially directed flow. ProvisioD o~ substaD-
tially circumferentially conti~uous outwardly directed
flaDge meaDS OD the tapered deflecti~g means, spaced ~rom
tbe ape~, whicb coact with the de~le~cted li~uid, enhances
conversion of the liguid stream into a radiall~ directed
spra~. CoDvenieDtly the spray is allowed to fall onto
a slopiDg sur~ace down whi~h it cascades to a secoDd
regioD iDto which fresh air flows, the cascading liquid
preferably being atomised further as it enters the secoDd
resioD so that the ~resh air and li~uid dropl~ts i~termingle
in the second re~ion to further aerate t~e liquid. ~he
sloping surface may be the first of a series of such
sloping surfaces, each of the second and any
~67~
subsequent sloping surface of the series extending below
the region to which the immediately preceding sloping
surface of the series slopes downwardly, so that the spray
that falls onto said first sloping surface cascades down
that surface to the respective region, is atomised further as
it enters that region so that the fresh air and liquid droplets
intermingle in that region to further aerate the liquid as
it falls through that region onto the second sloping surface
of the series down which it cascades to the respective region
and so on until the liquid falls onto the lowermost sloping~
surface of the series from which it is returned to the tank,
each such surface being arranged so that liquid received on it
cascades down it to the next region where it is atomised
and aerated further. Part of the stream of liquid drawn from
the settling tank may be bled from the main stream of liquid
that is aerated outside the mass of liquid stored in the tank,
the bled liquid being injected back into liquid contained
within the settling tank in order to generate movement of the
liquid that is contained within the settling tank. Fresh air
flow into the or each region conveniently is induced by the
passage of liquid or liquid spray to and through that region.
According to another aspect of this invention
~ 7~ ~
there is provided apparatus for use with a machine tool
s~stem ha~ing a settling tank through which liquid coolant/
lubricant is recirculated during normal operatioD, the
apparatus being e~fective to aerate the liquid stored iD
said SettliDg taDk aDd comprising control mea~s which
are adapted to,sense the operational state of the machine
tool ~ystem, liquid flow iDducing meaDs which are adapted
to draw li~uid from the ta~k, the control meaDs beiDg
operatively associ at~d with the liquid flow induciDg means
such as to actuate the liquid flow iDduciDg means to draw
liquid from the tan~ wheD the~ ~ense that the machine tool
system is shut down, aerating meaDs disposed ou~side the
mass o~ liquid sto~ed in the taDk a~d connected i~ a
liquid recirculatioD path with the tank and the liQUid
flow inducing means, the aeratiDg means being for aerating
liquid drawn from the tank b~ ~aid liquid flow iDduciDg
means and thereafter returniDg aerat,ed liquid to the tank.
Preferably said coDtrol means and said liquid f~ow
inducing means are arranged suc~ that the liquid flow
induciDg means are activiated continuously whilst the mach-
iDe tool s~stem is shut dowD so that a stream of liquid is
drawD continuously from the tank, aerated outside tke mas~
o~ liquid stored iD the taDk and retulned to the mass of
liquid stored in the tan~ coDtiDuousl~ whilst the sy~tem is
shut dowD~ ~he aerating means ma~ include a region iDto
which fresh air ~lows and means for converting liquid draw~
from the'taD~ by said liquid ~low inducing means into a
spray iD that region so that fresh air and the spra~ iDter-
mingle in that region to aerate the liquid and may be arra-
nge such that flow o~ ~resh air into
-- 5 --
.
~ 76~
the region is ind~ced b~ liquid flow through the aeratlDg
mea-Ds .
~ he aerati~g meaDs may comprise a hollow casing,
aD iDlet duct, a deflector which has a tapered surface
and which is supported within th~ hollow casiDg so that
its tapered surface tapers towards the iDlet duct with
wbich it is substaDtially coasial and so that its radially
outermost perlphery is spaced from the adjace~t wall of
the casing, aDd ap~rture means iD the easing wall through
whicb fresh air from outside the casi~g ~low into the
region that extends between tbe tapered surface o~ the
deflector aDd the adjace~t wall of tbe hollow casing, the
arrangemeDt being such that, iD use of the apparatus,
a stream of liquid that is to be aerated is directed
throu~h the inlet duct o~to the tapered sur~ace Or the
deflector b~ which it is deflected to form a substantiall~
circumrerentially contiDuous radially directed flow which
forms a liquid spra~ within said region aDd which draws
fresh air iDto the interior Or the casiDg through said
aperture means, the ~re~h air and tbe spray intermingling
within said regioD to aerate the liquid.
.
67~
Preferably a radially outwardly directed flange
i~ formed at the radially outermost periphery of the
deflector in order to assist in the conversion of the
liquid stream into a radially outwardly directed flow
of spray. Conveni~tly the flange tapers tow~rds
the large end of the tapered surface. ~`he deflector
may be pyramid shaped and such a flange may be formed
along ea~h edge of it~ base.
Preferably the hollow casing is adapted to be
mounted for use with the inlet duct formed in its top
surface. One or more members may be supported
within the hollow casing below the deflector, the upper
surface of each such member sloping downwardly from
one end which rests against a respective wall of the
hollow c~sing to another end which is spaced from the
opposite wall of the hollow casing. Pre~erably there
are several such member~ and they extend one below the
other~ alternate ones of the members resting against
alternate ones of the pair of opposed walls of the
hollow casing so that the spray that has ~ntermingled
with fresh air in the said re~ion falls onto the
upper surface of the uppermost one of said members
and cascades down that surface to a second reg~on,
~hich is formed between the lower end of that member
and the ad~acent wall of the casing, to fall throug~h
., .
_ 7 _
.
.
,
~ 6716~
that second re~ion onto the upper surface of the
next to uppermost member, cascade down the upper
surface of that next to uppermost member to a third
region, which is formed between its lower end and
the adjacent wall of the casing, and so on until it
reaches the bottom of the loA!ermost downwardly sloping
member from whence it flows back into the settling
tank. Conveniently further apertures are formed in
the casing wall ad~acent each of the regions that
are formed between the lower end of the downwardly
sloping members and the adjacent; wall of the casing
80 that fresh air from outside t;he casing can flow
into the respective region to intermingle within
that region with liquid spray which passes through
~hat region en route from one to the other of a
juxtaposed pair of the downwardl~ sloping members.
Preferably the hollow casing 19 adapted to be mounted
above liquid contained within the settling t~nk so
that the lower end of the upper surface of the lower-
most downwardly sloping member is below the level of
liquid within the settling tank during operation of
the apparatus to aerate liquid drawn from the settling
tank. Conveniently the or each member has an upwardly
directed flange at the lower end of its downwardly
sloping surface. ~he upper edge of the or each
-- 8 --
~L16~76a~
upwardly dlrected flange may be notched. Conveniently
further apertures are formed in the casing wall
ad~acent each of the regions that are ~ormed between
the lower end of the downwardly sloping members and
the adjacent wall of the casing so that fresh air from
outside the casing can flow into the respective region
to intermingle within that region with llquid spray
which traverses through that region whilst passing from
one to the other of a ~uxtaposed pair of the downwardly
sloping members. ~he further apertures may be
arranged such that the flow of fresh air into each
region is indubed by the passage of spray through tha-t
region. Preferably the hollow casing is adapted to
be mounted above liquid contained within the settling
tank so that the lower end of the upper surface of the
lowermost downwardly sloping member i-s below the level
of liquid within the settling tank during operation of
the apparatus to aerate liquid drawn from the settling
tank, the lowermost downwardly sloping member serving as
said means for returning ~erated liquid to the tank.
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_ g _ .
~3~3L67~
One embodiment of this invention will be describednow by way of example, with reference to the accompanying
drawings, of which:- .
~ igure 1 i8 a schematic illustration of a system
for aerating liquid contained within a machine tool
system settling tank in accordance with this invention;
~ igure 2 is a side elevation of a practical
embodiment o~ the system illustrated in ~igure 1, the
settling tank being shown chain dotted and partl~
broken away for convenience;
~ igure 3 is a plan view of ~igure 2;
Figure 4 is an end elevation o~ Figure 3;
Figure 5 is a transverse cross sec-tion in a
~ertical plane of the aerator unit of the system illus-
trated in ~igures 2 to 4t the unit being drawn to a
larger scale than in Figures 2 to 4; and
Flgure 6 i9 a section on the line VI~YI of ~igure
5"
.
Referring to ~igures 1 to 4, a settling tank 10 of a
- 10 -
. ~
.
, ~ .
-
;76~
machine tool system stores liquid, convenientlya mixture of oil and water, which iQ for use as a
coolant and/or a lubricant in a machining operation
carriedout at each machine station of each machine
tool of the system. ~he tank contains rotary drum
~ilter apparatus (not shown) which has its outlet
connected to a pump by which li~uid withln the tank
is drawn from the tank through the rotary drum filter
apparatus for distribution to each machine station of
each machine tool of the ~ystem, ~he pump is.located
outside the tank. ~he rotary drum filter apparatus
is usually located at the cent.re of the tank 10.
~ iquid used as a coolant or a lubricant in a
machinin~ operation carried out at eLlch machine station
of each machine tool of the system is collected and
returned to the tank 10. The returned liquid, together .
with soils, dirt, swarf and other foreign matter
collected with it,. is discharged into the tank at one
end 11 which is ~loped suitably. Figure 4 shows that
the width o~ the tank 10 at the top is approximately
three times that at the bottom, the side walls of the
tank tapering inwardly between the top and bottom
portiQns of the tank. A conveyor runs along the length
of the bottom section of the tank and up the slope
at the end 11 of the tank, A part 12 of the conveyor
is shown in ~igure 1 at the end 13 of the tank opposite
.
7~
the ~loping end 11. Soils, dirt, swarf and other
foreign matter discharged into the tank with liquid
returned from the machine tools of the machine tool
system gravitate to the narrow bottom section of the
tank and onto the upper run of the conveyor and are
carried by -that conveyor out of the tank when the
machine tool system is running.
~ igure 2 shows that a motor 14 is drivingly
coupled to a pump 15, the motor 14 and the pump 15
being mounted outside the tank 10 and below one of the
sloping side wall portions o~ the tank 10, Operation
of the motor 14 is controlled by the control system of
the machine tool system B0 that it is energised to
drive the pump 15 when the machine tool system is shut
down.
~ he inlet of the pump 15 is connected to one end
of an inlet pipe 16 which passes in a fluid tight mann;er
through an aperture in a wall of the tanX 10 and which
i~ open at its other end which is located just above
the upper run of the part 12 of the conveyor. Xence
the open end of the inlet pipe 16 is located as near
to the bottom of the tank 10 as is practicable and alqo
as close as is practicable to the end wall 13 that is
opposite the sloping end 11 at which liquid is discharged
into the tank along with 80ils, dirt, swarf and other
foreign mat-ter. The liquid ad~acent the end wall 13
- 12 -
. . , .
:
76 D ~ ~
of the tank 10 tends to be the most stagnant liquid
s~ored ~ithin the tank.
lhe outlet of the pump 15 i9 connected by a
horizontal pipe 17, which run~ outside the tank 10
for substantially ths total length of the tank 10, to
a branch pipe coupling 18 which has two outlets of
diffexent diameter. ~he larger diameter outlet of
the branch coupling 18 is connected by an angled pipe
19 to an i.nlet duct 21 of an aerator unit 22. ~he
smaller diameter outlet of the branch coupling 18 iB
connected by a small bore pipe 23 to an injector 24
which is located substantially at the centre of the
tank 10, below the normal level of liquid stored therein
and adJacent the sloping end 11 of the tank 10. The
small bore pipe 23 passes in a fluid tight manner through
an aperture in a wall of the tank 10. A valve 25 in
the small bore pipe 2~ controls liquid flow through
that pipe. ~he arrangement of the pipes 19 and 23
and the ~alve 25 is such that the vast majority of
liquid drawn from within the tank 10 by the pump 15
i~ directed to the aerator unit 22 via the angled
pipe 19~ approximately 8~ of the total Yolume of liquid
drawn from the tank 10 by the pump 15 being directed
through the small bore pipe 23 and the in~ector 24
into liquid within the tank,
- 13 -
, .. . .. .....
:
:
1 l l6 7~;~
~ he aerator unit 22 will be described in detail
now with reference to ~igures 5 and 6. It comprises
a hollow casing of generally rectangular box construc-
tion formed basically of an angle iron framework clad
with sheet metal panels which form its vertical side
walls 26, 27, 28 and 29 and a top cover 31. The angle
iron framework includes four vertical legs, one at
each corner of the cas~ing and four horizontal lengths
of angle iron at the top. The casing is open at the
bottom and is supported ~rom the structure of the tank
lO by suitable support means so that its longitudinal
axis i~ vertical and so that the bottom of each of the
four legs o~ the angle iron framework is immersed in :
liquid con~ained within the tank lO. ~he side wall
panels 2fi to 29 are shorter than the vertical legs of
the angle section framewor~ and their lower edges are
above the level of liquid contained within the tank
lO. ~he casing is orientated so that -the wider side
wall panels 26 and 27 are substantially normal to the '
longitudinal axis of the tank lO.
~ he top cover 31 carries the in.let duct 21
~hich is a vertical tube which passes through a
ciroular hole within which it is spigotted and which
i8 formed at the centre of the top plate 31. A pair
oi~ angled strips 32 and 33, which comprise portions :~
- .
. .7 . .. ,
676~ "
of the top panel 31 bent downwardly from the plane
of the remainder of the top panel 31, extend paxallel
to the wider side wall panels 26 and 27 over substan-
tially the total di~tance between the horizontal
length.q of the angle section framework to which the
narrower side wall panels 28 and 29 are fastened.
Each angled strip 32, 33 is flat and slopes downwardly
in direction outwards from the vertical axis of the
aerator unit 221. The wider side wall panels 26 and
27 pro~ect above the horizontal lengths of the angle
section framework to forn; flanges 34 and 35 which are
bent inwardly towards the axis of` the aerator unit 22
so that each of them extends substantially parallel
to the ad~acent angled strip 32, 33. Each angled
strip 32, 33 co-operates with the adjacent angled
flange 34, 35 to form an angled inlet slot through
which air can be drawn into the interior of -the hollow
casing from outside, air drawn in through each such
angled slot being directed towards the adjacent wider l
side wall panel 26, 27. . ,~
A sheet metal de~lector 36 comprises a pyramid-
shaped structure with a s~uare base and four outwardly
directed angled flanges 37, 38, 39 and 41 which extend
one along each edge of the base of the pyramid-shaped
structure. Each angled flange 37, 38, 39 and 41 and
.
- 15 -
~6'76`~ :;` ` ` `
the ad~acent triangular face of the pyramid-shaped
structure Or the deflector 36 converge towards the
respective edge of the square base. Ths deflector
36 is supported by an angle iron support framework
42 ~o that it is coaxial with the inlet duct 21
and so that its apex is at its end nearer to the "~
inlet duct 21. There is a space between each angled
flange 37, 38, 39, 41 and the adjacent wall panel 26
27, 28 and 29 of the hollow casing.
A pair o~ angle iron support members 43 and 44
slope downwardly from the wider side wall panel 27 to
the wider side panel 26, each support member 43, 44
lining a respective one of the narro~ver side wall panels
28 and 29. A planar sheet metal member 45 is supported
at either edge by the two members 43 and 44 so that it
spans the gap between those members 43 and 44 and slopes
downwardly. The upper edge of the sheet metal member
45 abu~s the vertical legs of the angle section frame-
work to which the wider side wall panel 27 is fastened.
The planar sheet metal member 45 has an upwardly
directed flange 46 extending over substantially the full
distance between the narrower side wall panels 28 and
29 at its lower end~ ~even notches are formed in the
edge of the ~lange 46 at equi~spaced intervals. ~here
is a space between the ~lange 46 and the ad~acent wider
` - 16 -
-- .
1~67'16~
'sheet metal panel 26 which carries an upwardly
opening sheet metal shroud 47. The interior of
the shroud 47 communicates with the space between
the flange 47 and the panel 26 through an aperture
which i9 formed in the panel 26 opposite the flange
46.
A second downwardly sloping planar sheet metal
member 45A is supported below the planar sheet metal
member 45 in a similar manner by angle iron support
members 43A and 44A. ~he upper edge of the second
member 45A abuts the vertical legs of the angle iron
~ramework to which the wider sheet metal side wall
panel 26 i9 attached just belowr the aperture that is
formed in that panel 26 ad~acent the lower end o.~ the
shroud 47. A notched flange 4.6A is formed at the
lower end of the second member 45A and a space is
formed between the notched flange 46A and the adjacent
wider sheet metal side wall panel 27. An upwardly
opening sheet metal shroud 47A carried by the wider
sheet metal side wall panel 27 opens at ~ts lower end
into the space formed between the notched panel 46A
and that panel 27 through an aperture fo med in that
panel 27 opposite the notched flange 46A.
A third downwardly sloping planar sheet metal
member 45B is supported below the ~econd member 45A in a
.
r -
~67~
similar manner by another pair of angle iron 5upport
member 43B and 44B~ the upper edge of the third
member 45B being in abutment with the vertical legs
of the angle iron framework to which the wider sheet
metal .side wall panel 27 is attached just below the ~.
aperture that is formed in that panel 27 opposite the
notched flange 46A. A notched flange 46~ is formed
at the lower end of the third member 45B and there is
a spaee between that notohed flange 46B and the
adjacent wider sheet metal side wall panel 26.
The interior of a second upwardly opening sheet metal
shxoud 47~, which i.s carried by the panel 26 below the
first such shroud 47, communicates with the space ~or~.led
between the notched flange 46~ and that pane' 26 throu~h
an aperture which i3 formed in that panel 26 opposite
the notched flange 46B.
A ~ourth sheet metal member 48 is supported by
suitable angle iron members below the third downw~rdly
sloping planar sheet metal member 45~. The fourth
sheet metal member 48 extends over substantially the
full-distance between the narrower sheet metal side
~all panels 28 and 29, like the other three sheet
-met&l ~embers 45, 45A and 45~, but does not slope
downwardly over its whole length. That partt 48A,
of the fourth sheet metal member 48 that extends below
. - 18 -
6~
the space between the edge of the notched flange
46~ of the third downwardly sloping planar sheet
metal member 45B is substantially hori~ontal and
extends almost to the centre oi~ the ho]low casing.
~he fourth member 48 slopes downwardly from the inner
edge of the horizontal portion 48A to a point which is
just short of the wider sheet metal side wall panel 27
and which is below the level of liquid stored within
the tank 10, even when the pump 15 is being driven to
draw liquid from the tank and circulate liquid through
the pipes 16, 17, l9 and the aerator unit 22. ~he
lower end of the downwardly sloping portion 48~ of the
~ouxth member 48 is connected by a second short
horizontal,portion 48C -to the :Lower ends of the
vertical legs of the angle sec-tion framework to which
the wider sheet metal side wall panel 27 is attached.
The aerating apparatus described above with
'reference to and as illustrated in the accompanying
drawings is inoperative whenever the machine tool
system is in operation. However, as soon as the
machine tool system is shut down and the conveyor
brought to a halt, the motor l~ is energised and the
pump 15 is driven to draw liquid from within the tank
lO, adjacent the end 13 of the tank, and to feed the
majority of that liquid through the pipes 17 and l9
.~ .
-- 19 - .
.. ` ' ' ~
, .
7~
to the aerator unit 22 through its inlet duct
21. ~he minor part of the liquid that is directed ~.
through the small bore pipe 23 is in~ected back into
the liquid within the tank 10 through the injector
24 adjacent the end 11 of the tank 10 into which the
liquid, together with swarf, ~oils, dirt and other
foreign matter is discharged durin~ operation of the
machine tool system, such liquid injected into the
tank 10 through the in~ector 24 generating movement
of liquid within the tank 10 to reduce stagnation of
that liquid.
~ he main stream of liquid that is directed into
the aerator unit 22 through thi3 inlet 21 impinges the
surfaces of the pyramid-shaped structure of the deflector
36 and is deflected by that impingement and by the
action of the angled deflector flanges 37, 38, 39 and
41 so that it is broken up into a radially outwardly
directed spray of liquid drople~s which extends sub-
stantially continuously around the circumference of
the deflector 36. ~he spray is directed across the
space between the deflector 36 and the side wall
panels 26, 27, 28 and 29 and some of that spray
impinges those side wall panels 26 to 29 and rebounds
~rom those side wall panels 26 to 29 so that it is
.. .
- 20 -
,
r J
16~
'broken up into an even flner spray. Spray within
the space between the deflector ~6 and the wider
side wall panel 27 as well as spray within the spaces
between that deflector 36 and the narrower side wall
panels 28 and 29 falls onto the third downwardly
sloping planar sheet metal member 45 therebelow.
Spray in the space between the deflector 36 and the ;
wider side wall panel 26 falls through the space
between -the notched flange 46 and that panel 26 on-to
the downwardly sloping surface of the second planar
sheet metal member 45A.
The flow of liquid through the inlet duct 21
onto the deflector 36, radiall~y outwardly from that
deflector 36 towards the side wall panels 26, 27, 28
and 29 and then downwardly onto the downwardly sloping
members 45 and 45A therebelow, induces air to flow
into the hollow ca~ing through the inlets formed by
the parallel pairs of angled strips and flanges 32 and
34, 33 and 35 and fresh air so induced to flow into
the interior of the hollow casing intermingles with
the liquid droplets of the spray within the spaces
formed between the deflector 36 and the side wall
panels 26, 27, 28 and 29 of the hollow casing and
purges that spray of bacteria~
~ iquid that falls onto the first downwardly
- 21 -
~676~ `
sloplng planar sheet metal member 45 tends to bounce
on that member 45 and cascade~ down that member 45
and over the notched edge of the notched flange 46
into the second space formed between that notched
~lange 46 and the wider ~heet metal side wall panel
26. Hence the liquid is ~urther broken up into an
atomis~d spray of liquid droplets which falls throu~h
that second space onto the second downwardly sloping
planar support member 45A. Air is induced to flow
into that second space through the upwardly opening
shroud 47 and'the aperture formed in the side wall
panel 26 at the foot of that shroud opposite the
notched ~lange 46 and that air in-termingles with the
liquid spray within that second space and further
purges that liquid.
It'will be appreciated that spray that fall~
onto the second downwardly sloping planar shee-t
metal member 45A cascades down that slope to the third
~pace where it intermingles with further fresh air
drawn into that third space through the upwardly
opening shroud 47A and the aperture formed in the
w~der sheet metal side wall panel 27 opposite the
notched flange 46A and that that liquid is further
purged in that ~pace, It will be appreciated al~o
that thè process is repeated again in the fourth space
' that is formed be-twee~ the notched flange 46~ and the
wlder side wall panel 26.
- 22 -
, ,
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~ . .
67~i~
~ iquid that falls through the space formed between
the notched panel 46B and the wiaer side wall panel 26
fallR onto tne lowermost sheet metal member 48A and
flows down the sloping portion 48A of that panel 48 into
the liquid in the tank 10 within which the lower edge
of that panel portion 48A is immersed. A tendency -~
for foam t~ be formed by the action of pouring liquid
into liquid contained in the settling tank 10 is
minimised by arranging for the bottom of the downwardly
sloping portion 48~ to be always immersed in that
liquid so that the liquid output from the aerator unit
22 is returned relatively gently into the main body
of the liquid in the settling tank 10.
~ he notches in the edges of the notched flanges
46, 46A and 46~ assist in breaking up and atomising
liquid that cascades down the respective downwardly
slop~ng planar member and over the notched surfaces
into the respective space formed between those notched
edges and the adjacent wider side wall panel 26 or 27, :
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