Abstrict A flow meter insertable into a riser tube or an intake tube of
an aquarium filter includes an insert placed in the tube and along
which water flows as it is drawn by means of a power head, impeller
or pump. A flow restriction arrangement, defines a flow path with
respect to the insert. The insert carries an elongated slot with
a scale and has two oppositely directed semi-circular flanges dimensioned
so that they block water from flowing through the entire area of
the container but allow the water to enter on one side of the insert,
then flow into the slot and exit along the opposite side of the
insert. A metering float inserted adjacent the scale and is positioned
at a level height relative to the flow rate of water passing the
insert. This value can be read on the scale.
Claims What is claimed is:
1. A flow meter for insertion in a flow tube of an aquarium filter
for measuring the flow rate of water being filtered and returned
into an aquarium tank, the flow meter comprising:
an insert snugly fit within the flow tube;
scale means provided with respect to said insert;
a metering float for floating in the flow tube adjacent the scale
means for indicating on said scale means a flow rate of water passing
through said container, said insert subdividing an interior of said
tube into two opposite sides along an axis of said tube and externally
of said insert, said insert being provided with an elongated slot;
and
means defining a flow path of water passing said insert, said flow
path defining means being constructed so as to permit water to flow
within said tube along one of said sides into said slot and along
said another opposite side, to raise the float to a height dependent
upon the rate of flow of the water.
2. A flow meter as in claim 1 wherein said insert comprises, a
plate formed with said slot, and two end flanges extending perpendicular
to said plate and in two diametrically opposite directions therefrom.
3. A flow meter as in claim 2 wherein said flow tube is substantially
cylindrical.
4. A flow meter as in claim 3 wherein said flanges are substantially
semi-circular.
5. A flow meter as in claim 4 wherein said insert includes at
each end thereof a narrow finger-like strip extending normal to
said plate and in the direction away from a respective end flange;
said flanges, said slot and said strips defining said flow path
means.
6. A flow meter as in claim 5 wherein each said strip has an end
face facing away from said end flange, said end face forming with
a diametrically opposing point of said semi-circular flange a dimension
corresponding to an inner diameter of said container.
7. A flow meter as in claim 6 wherein said plate has a width corresponding
to the inner diameter of said container.
8. A flow meter as in claim 1 wherein said slot has substantially
parallel side edges.
9. A flow meter as in claim 8 wherein said scale means includes
a varying scale provided on a front side of said insert laterally
of said slot.
10. A flow meter as in claim 1 wherein said slot has a varying
width along an axis of elongation thereof.
11. A flow meter as in claim 1 wherein said flow tube is a riser
tube of an undergravel filter.
12. A flow meter as in claim 11 wherein an air lift tube is provided
in the riser tube above said flow meter.
13. A flow meter as in claim 11 wherein said riser tube supports
a power head at an upper edge thereof for drawing water through
said riser tube, said power head being downstream of said flow meter.
14. A flow meter as in claim 1 wherein said flow tube is an intake
tube of an external aquarium filter.
15. A flow meter as in claim 14 wherein said intake tube is connected
to a pump of said aquarium filter, said pump drawing water through
said intake tube, said pump being downstream of said flow meter.
16. A flow meter for insertion in a flow tube of an aquarium filter
for measuring flow rate of water being filtered and returned into
an aquarium tank, the flow meter comprising:
an insert snugly fitting in the flow tube;
scale means provided with respect to said insert;
a metering float floating adjacent said insert for indicating on
said scale means a flow rate of water passing through the flow tube;
and
means defining a flow path of water passing adjacent said insert,
said insert including a plate being of a width corresponding to
an inner diameter of said flow tube and having a central elongated
slot, said insert further including at two opposite ends thereof
respective flanges extending in opposite directions from and perpendicular
to said plate, so that said flanges respectively block a flow path
of water at opposing ends of the two sides of said plate causing
the water to flow along one side of the plate, then into said slot
and then along the other side of the plate.
17. A flow meter as in claim 16 wherein said flanges are semi-circular
and together define a diameter corresponding to an inner diameter
of said container.
18. A flow meter as in claim 17 wherein said insert further includes
two narrow strips each secured to a respective one of said flanges
and extending away therefrom.
19. A flow meter for insertion in a flow tube of an aquarium filter
for measuring the flow rate of water being filtered and returned
into an aquarium tank, the flow meter comprising:
an insert snugly fit within the flow tube;
scale means provided with respect to said insert;
a metering float for floating in the flow tube adjacent the scale
means for indicating on said scale means a flow rate of water passing
through said container, said insert being provided with an elongated
slot; and
means defining a flow path of water passing said insert, said flow
path defining means being constructed so as to permit water to flow
along one side of said insert into said slot and along another opposite
side of said insert, to raise the float to a height dependent upon
the rate of flow of the water,
said insert comprising a plate formed with said slot and two end
flanges extending perpendicular to said plate and in two diametrically
opposite directions therefrom.
20. A flow meter as in claim 19 wherein said flow tube is substantially
cylindrical.
21. A flow meter as in claim 20 wherein said flanges are substantially
semi-circular.
22. A flow meter as in claim 21 wherein said insert includes at
each end thereof a narrow finger-like strip extending normal to
said plate and in the direction away from a respective end flange;
said flanges, said slot and said strips defining said flow path
means.
23. A flow meter as in claim 22 wherein each said strip has an
end face facing away from said end flange, said end face forming
with a diametrically opposing point of said semi-circular flange
a dimension corresponding to an inner diameter of said container.
24. A flow meter as in claim 23 wherein said plate has a width
corresponding to the inner diameter of said container.
25. A flow meter as in claim 19 wherein said slot has substantially
parallel side edges.
26. A flow meter as in claim 25 wherein said scale means includes
a varying scale provided on a front side of said insert laterally
of said slot.
27. A flow meter as in claim 19 wherein said slot has a varying
width along an axis of elongation thereof.
28. A flow meter as in claim 19 wherein said flow tube is a riser
tube of an undergravel filter.
29. A flow meter as in claim 28 wherein an air lift tube is provided
in the riser tube above said flow meter.
30. A flow meter as in claim 29 wherein said riser tube supports
a power head at an upper edge thereof for drawing water through
said riser tube, said power head being downstream of said flow meter.
31. A flow meter as in claim 19 wherein said flow tube is an intake
tube of an external aquarium filter.
32. A flow meter as in claim 31 wherein said intake tube is connected
to a pump of said aquarium filter, said pump drawing water through
said intake tube, said pump being downstream of said flow meter.
Description BACKGROUND OF THE INVENTION
The present invention pertains to aquarium filters, and more particularly
to a device for measuring a flow rate of water flowing from an aquarium
tank through a filter and returned to the aquarium tank. More specifically,
the invention pertains to a flow meter insertable in a flow tube
leading to a pump or power head by which water is drawn through
the flow tube and is returned to the aquarium tank.
External and internal aquarium filters are regularly utilized for
aeration and filtration of aquarium water and also to provide circulation
to the water in the aquarium tank. One type of aquarium filter is
an externally mounted filter which accommodates a filtration medium
and includes an impeller mechanism inducing the circulation of water
from the aquarium through the filtration medium and then returns
the clean water to the aquarium. Another type of aquarium filter
is an internal filter typically disposed beneath the surface of
the aquarium bed and known as an undergravel aquarium filter. Undergravel
aquarium filters are equipped with a riser tube which conducts water
passed through the gravel bed and the perforated plate of the filter
back to the water within the aquarium tank above the perforated
plate. So-called power heads are utilized for drawing the water
through the gravel bed and into a chamber under the perforated plate
of the filter. The power head then causes water to flow upward in
the riser tube and back into the aquarium tank. Alternately, an
air pump coupled to an air store can be used with the air store
suspended within the riser tube and causing an air lift of the water
in the riser tube.
In certain cases, it may be desirable to measure the flow rate
of water flowing through the filter of the external or internal
type and circulated back into the aquarium tank.
Flow meters for measurement of fluid flow rate are well known in
the art. One of the known types of flow meters is a rotameter which
is comprised of a float positioned inside a tapered tube and, by
action of fluid flowing up through the tube, is moved inside the
tube. A flow restriction is provided at an annular area between
the float and the tube and this area increases in the direction
of rise of the float. The pressure differential is fixed, determined
by the weight of the float and the buoyant forces. The annular area
and hence the float level increase with the flow rate. The rotameter
is calibrated for direct flow reading by etching an appropriate
scale on the surface of the tube. The calibration depends on the
float dimensions, tube taper and fluid properties.
In using a flow meter for an aquarium filter it is desirable to
have the flow meter easily cleaned, simple in operation, safe for
the fish inhabitants of the aquarium, and preferably of a type easily
replaceable.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a flow meter
for insertion in a flow tube connected to a power head or pump which
draws water through the flow tube, the water coming from an aquarium
tank, and returns it back to the tank.
It is another object of the present invention to provide a flow
meter for measuring flow rate of water being filtered and returned
into an aquarium tank.
It is a further object of the invention to provide a flow meter
having a wide volumetric range.
Yet another object of the invention is to provide a variable-area
flow meter which is easy to use with aquarium filters.
Briefly, in accordance with the invention, there is provided a
flow meter for insertion in a flow tube of an aquarium filter. The
flow tube can be the riser tube of an undergravel filter having
a power head at its top for drawing water through the tube and past
the flow meter, or with an air lift formed in the riser tube. Alternately,
the flow can be the intake tube of an external aquarium filter having
one end inserted in the tank and another end discharging into the
filter. An impeller at the discharge end draws water through the
intake tube and past the flow meter.
The flow meter includes a substantially flat elongated plate snugly
fit within the flow tube so that preferably no water can leak on
the sides between the edges of the plate and the inner wall of the
flow tube. The plate substantially splits the tube longitudinally
in two halves. The plate includes an elongated slot along its length
and two end flanges extending normal to and oriented in two opposing
directions relative to the plate. Each flange is a semicircle that
closes off its half of the flow tube. A scale is provided along
the slot, and a metering float is positioned between one side of
the plate and the container wall in between the two flanges. Water
enters the flow tube and as it gets to the flow meter is blocked
on one side by the lower flange and is forced to flow along only
one side of the plate. It is on that side that the float is positioned.
The water flows along side the plate but is blocked from exiting
by the upper flange. The water therefore flows through the elongated
slot to the other side of the plate. The flowing water crossing
through the slot lifts the float. The height to which it lifts the
float is dependent upon the rate of flow of the water. This height
can be calibrated in terms of rate of flow and read out on the scale
adjacent the slot.
In an embodiment, the insert includes two narrow fingers each extending
normal to the plate and away from the respective flange provided
on the end of the insert to provide a tight fit of the insert in
the flow tube.
In an embodiment, the metering float is ball-shaped.
In an embodiment, the flow meter is positioned in the aquarium
filter downstream of the power head, pump, or air store.
The aforementioned objects, features and advantages of the invention
will, in part, be pointed out with particularity, and will, in part,
become obvious from the following more detailed description of the
invention, taken in conjunction with the accompanying drawing, which
form an integral part thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front elevational view of the flow meter inserted in
a flow tube according to the invention;
FIG. 2 is a rear elevational view of the flow meter of FIG. 1;
FIG. 3 is a front elevational view of an alternate embodiment of
the flow meter.
FIG. 4 is a side view of an undergravel filter located within an
aquarium tank and a riser tube with the flow meter of FIG. 1 inserted
therein;
FIG. 5 is a view similar to FIG. 4 and showing the use of an air
lift arrangement in the riser tube; and
FIG. 6 is a perspective view of an external aquarium filter with
the flow meter inserted in the intake tube of the filter.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, therein shown a flow meter which
is designated generally by reference numeral 10 and is inserted
in a substantially cylindrical flow tube 12 of transparent material,
for example, glass or plastic. At its upper end will be a pump,
vacuum, impeller, or the like to draw water up through the flow
tube. An insert 14 comprised of a flat elongated plate 24 is placed
in the flow tube 12 so that two oppositely oriented end flanges
16 and 18 provided on plate 24 snugly fit within the interior of
tube 12. Each end flange 16 18 is of a semi-circular configuration
and has an outwardly extending narrow finger 20 22. Each finger
20 22 diametrically opposes the respective semi-circular flange.
The end face of each finger includes with the remotest point of
the semi-circular flange a diameter which corresponds to the inner
diameter of the flow tube 12 so that there is a reliable and tight
fit of insert 14. This snug fit will also serve to hold the insert
at a predetermined level in flow tube 12. A substantially triangular
plate 26 can be provided at each end of plate 24 between the end
portion of plate 24 and each outwardly protruding end flange 16
18. Each, plate 26 is attached to the respective surfaces of insert
14 to increase rigidity of the end flange 16 18.
The plate 24 is formed with an elongated slot 28 extending therethrough
and forming a path for water flow, as will be explained hereinafter.
A scale 30 is provided on a front side 38 of plate 24 adjacent
the elongated slot.
It is to be understood that the straight-line slot shown in FIGS.
1 and 2 is only as an exemplified embodiment. Slots of varying cross-sectional
area can be provided, as for example, the upwardly flaring slot
28 of FIG. 3. Such varying the size of the slot varies the area
for the flow path. Such variations can be used to adjust the scale
30' increments, and to control the other variables such as the weight
of the float, etc.
It is to be pointed out that the diameter of each flange 16 18
and the width of elongated plate 24 correspond to the inner diameter
of flow tube 12 whereby no flow is permitted between the inner wall
of tube 12 and each of the opposite lateral side edges 32 34 of
plate 24. Likewise, each flange blocks half of the flow tube serving
to divert the flow path to the opposite side of the plate 24.
A metering float 36 is provided, in the exemplified embodiment
of the present invention, as a ball located at a back side 40 of
plate 24 between the flat surface of the plate and the inner wall
of tube 12.
The flow path for the water entering a lower distal end 42 of flow
tube 12 as shown by arrows, is blocked by lower flange 18 and is
directed into a channel included between the inner wall of tube
12 and the back side 40 of plate 24. Then water, prevented to flow
upwardly towards an upper distal end 44 of flow tube 12 by the upper
flange 16 is forced through elongated slot 28 to the front side
of plate 24 and, from there, unobstructed, exits from the open end
44 of flow tube 12. Thus, the flow restriction area in the flow
meter according to the invention is provided in two semi-circular
channels 46 and 48 each limited by the front or back surface of
plate 24 respectively, and the facing inner wall of flow tube 12.
The ball-shaped float 36 will be positioned inside the flow tube
12 by action of water flowing up through the tube. The level position
of float 36 corresponds to the flow rate of water passing through
the flow tube this can be read out on scale 30.
Referring now to FIG. 4 there is shown an aquarium tank 50. An
undergravel filter 52 includes a gravel bed 54 which is supported
on a perforated flat supporting plate 56 of filter 52. A skirt 58
holds the gravel bed 54 in spaced relationship with a bottom wall
60 of the aquarium tank.
A riser tube 62 extends upwardly from a clear water chamber 64
below the perforated plate 56. A power head 66 is seated on an upper
edge 68 of the riser tube. The power head 66 which sucks water from
chamber 64 through riser tube 62 has a motor-driven water pump.
The construction of the power head is disclosed in detail, for example
in U.S. Pat. No. 4512724.
Water is filtered by filter 52. The aquarium contaminants drawn
between the particles of the gravel, which forms the aquarium bed,
is mechanically filtered as the contaminants become physically entrapped
in the gravel bed 54. Additionally, aerobic bacteria which accumulates
on the gravel and on the filter plate provides for biological filtration
of the aquarium water. Thereby, the aquarium gravel bed 54 serves
as a mechanical and biological filtering device which traps particles
and in addition, converts some sewage particles into non-toxic substances.
Power head 66 is provided with an outlet tube 70 which typically
has a nozzle which directs the water sucked by the pump of power
head 66 from chamber 64 back into the aquarium tank 50. Power heads
of this type can also be equipped with aeration means to aerate
the water returning into the aquarium.
The flow meter 10 described in connection with FIGS. 1 and 2 is
placed in the riser tube 62. The flow meter is frictionally positional
within the riser tube and is retained in place by a tight fit. The
filtered water collected in chamber 64 between the perforated wall
56 and the bottom wall of the aquarium is drawn from the chamber
by a suction action of the power head 66. Water sucked from chamber
64 rises along tube 62 and flows through the flow meter 10 before
it reaches the power head. Thus the flow rate is indicated by the
position of float 36 on scale 30 of the flow meter. The water sucked
by the power head is aerated in the power head and returned to the
aquarium tank 50 through outlet tube 70.
FIG. 5 shows an arrangement similar to FIG. 4 but now places the
flow meter further to the bottom of the riser tube 62. Above the
flow meter, and downstream thereof is placed an air store 67 connected
to an air tube 69 coupled to an air pump 71 supported externally
of the tank. Air pumped through the air store causes bubbles to
rise in the riser tube causing an air lift effect in the riser.
The flow meter will measure the rate of flow of the water.
With reference to FIG. 6 it will be seen that the flow meter 10
is employed in an aquarium filter apparatus generally designated
at 80 and comprising a container 82 accommodating a filter cartridge
84. The aquarium filter 80 is of a type which is placed externally
of the aquarium tank and is described in detail in applicant's U.S.
Pat. No. 4512885 which is incorporated herein by reference. Container
82 which is formed of transparent plastic material is covered with
a cover member 86 also of transparent plastic. The filtering chamber
within tank 82 is divided by the filter cartridge 84 inserted therein.
The compartment of tank 82 formed between a rear wall 88 of the
tank and the filter cartridge 84 is the filtering chamber whereas
the compartment formed forward of the filter cartridge 84 and extending
up to a front wall 90 defines a clean water compartment. Filter
cartridge 84 extends substantially over the entire height of tank
82. A water intake assembly 92 is positioned in tank 82. The intake
assembly is removable and comprises a substantially U-shaped intake
flow tube 94 including a first vertical leg 96 and a second vertical
leg 98 interconnected by a connecting leg 100. Vertical leg 96 terminates
at its lower end at a level lower than the termination of leg 98.
An upper distal end 102 of leg 100 extends beyond its interconnection
with leg 98 and is closed with a plug serving as a control valve.
The lower distal end of leg 98 terminates in a collar 104. An extension
tube (not shown) can be inserted into the collar 104. A rotor assembly
of an impeller-type 106 snugly fits into a chamber within a stator
unit.
With the intake assembly positioned in the filter container 82
the filter assembly 80 is then positioned over the upper edge of
an aquarium with a ledge 110 of a spillway 112 so as to retain the
filter in place at the upper edge of the aquarium tank.
When the filter 80 is properly positioned, the downwardly extending
water intake leg 96 reaches into the aquarium water. The motor 106
is then energized by connecting it to a source of energy. This will
then energize the stator and cause the rotor to turn. This in turn
will cause the motor impeller to begin pumping. As a result, the
contaminated water which is drawn up through the vertical intake
tube 96 and into the aquarium filter for filtration and subsequent
return to the aquarium.
Flow meter 10 is inserted in the intake flow tube 96. The flow
meter is secured in place by friction engagement with the inside
walls of the intake tube. The flow rate of the water drawn into
leg 96 from the aquarium tank is measured and indicated on the scale
of the flow meter 10.
In both arrangements of FIGS. 4 and 5 the motor pump or power
head is located downstream of the flow meter. The range of the flow
rate to be measured by the flow meter according to the invention
is typically between 5 gal/hr to 300 gal/hr.
There has been described heretofore the best embodiments of the
invention presently contemplated. However, it is to be understood
that various changes and modifications may be made thereto without
departing from the spirit of the invention. |