Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02663340 2009-04-07
INTAKE NOZZLE FOR A PUMP
This invention relates to an intake nozzle for a pump for removing
liquid from a surface.
BACKGROUND OF THE INVENTION
It is commonly necessary to pump liquid from a surface in the event of
a flood or spill, or from the bottom surface of a tank or containment area to
remove
the fluid.
Submersible sump pumps are available which sit flat on the surface
and can pump down to a relatively low liquid surface level. However these are
generally of low capacity and are unsuitable in situations where large volumes
of
liquid are to be pumped.
A larger volume of flow can be generated using a remote pump with an
intake line leading to the surface. Typically such pumps are provided with a
generally conical strainer device that fits on the end of the suction line to
prevent
debris from entering the pump suction. The problem with the strainer device is
that it
does not allow the pump to pump the fluid level down to the floor. The pump
loses
suction leaving a significant standing fluid level.
It is desirable to pump the fluid level down as much as possible before
losing suction.
The movement of fluid while pumping is caused by creating a pressure
differential so that the fluid flows from higher to lower pressure. Because of
the
design of the strainer, the pump loses suction while there is still a
significant amount
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of water to be pumped from a flat surface. This effect takes place because air
breaks through into the pump suction as the fluid level drops, due to the
design of
the strainer device. This also happens when pumping without the strainer
device.
SUMMARY OF THE INVENTION
It is one object of the invention to provide an improved intake nozzle
for a pump which allows liquid on a surface to be pumped down to a height of
liquid
close to the surface.
According to one aspect of the invention there is provided a intake
nozzle for a pump comprising:
a cylindrical duct portion defining a circular bottom mouth surrounding
a central upstanding axis of the duct portion with the bottom mouth arranged
to face
downwardly toward an upwardly facing flat surface from which liquid is to be
drawn
into the mouth;
the duct portion being arranged for connection to an inlet pipe of the
pump so that the pump draws liquid from the nozzle into the pump for
discharge;
a plate member surrounding the bottom mouth and defining a
downwardly facing nozzle surface for facing the flat surface, so that the
liquid is
drawn between the flat surface and the downwardly facing nozzle surface before
entering the bottom mouth;
a plurality of spacer members extending downwardly from the nozzle
surface for spacing the nozzle surface from the flat surface;
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the nozzle surface being shaped and spaced from the flat surface so
as to define an annular gap surrounding the bottom mouth which defines with
the flat
surface an annular area at the annular gap which is substantially equal to the
circular area of the bottom mouth;
the nozzle surface being shaped between the annular gap and the
mouth so as to define an inwardly and upwardly extending curved surface
portion
which is shaped such that an annular area between the surface portion and the
flat
surface at any circle surrounding the central axis of the bottom mouth is
substantially
equal to the circular area of the bottom mouth;
the plate member extending outwardly from the annular gap to an
outer peripheral edge of the nozzle surface so as to define a peripheral
intake mouth
between the flat surface and the outer edge of the downwardly facing nozzle
surface
through which the liquid is drawn to pass under the nozzle surface to the
bottom
mouth;
the nozzle surface being shaped such that, as it extends outwardly
from the annular gap to the peripheral mouth, the annular area at any circle
surrounding the central axis between the nozzle surface and the flat surface
increases with the radius.
The flat surface can be that of a floor, for example of a basement or
other flooded area, or can be a base of a tank, pool or other container to be
emptied.
Thus in this case the bottom surface of the nozzle simply sits on the floor or
base
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facing downwardly. Alternatively the flat surface maybe a surface forming part
of the
nozzle itself.
Preferably the nozzle surface is simply flat between the annular gap
and the peripheral mouth. Thus the gap remains constant and the increase in
circumference acts to gradually increase the annular area at each circle as
the
radius increases. Alternatively the gap may gradually increase or may
gradually
decrease provided the annular area increases, since the gradual increase acts
to
slow the velocity of the liquid as it enters and passes through the gap under
the
nozzle surface.
Preferably the outer peripheral edge is located at a diameter which is
at least double the diameter at the annular gap since this provides a
relatively large
area at the peripheral edge to cause a low velocity at the edge which
increases
significantly as it approaches the annular gap.
Preferably the annular gap is located at a diameter which is at least
double the diameter of the bottom mouth. In this way the liquid flow gradually
and
smoothly changes in direction from the horizontal direction under the nozzle
surface
into the vertical direction as it passes through the bottom mouth. It will be
appreciated that the larger the radius of the device, the more efficient it
will be at
reducing the gap so as to reduce the velocity and thus the likelihood of air
breakthrough at the gap. Different models can be provided for different pump
sizes
with different gaps and different overall diameters.
The suction tube can be integral with the duct portion of the nozzle or
CA 02663340 2009-04-07
can be separate with a suitable coupling.
Preferably the plate member is circular at the peripheral edge,
although other shapes are possible.
Preferably the duct is vertical and defines an upper open mouth, for
5 connection to the intake pipe of the pump, which is spaced above the plate
member.
This leads the liquid away from the nozzle with minimum direction changes,
although
the duct may include an elbow which changes the direction to a horizontal
direction
across the surface. The duct may contain a screen type filter to prevent
debris
entering the pump if the device loses contact with the surface while the pump
is
operating.
Preferably the spacer members extend from the nozzle surface at
positions spaced outwardly of the annular gap so as not to interfere with the
flow in
the area of the annular gap and the curved surface interconnecting it to the
bottom
mouth.
Preferably the spacer members are relatively small and thus are
arranged so as to avoid reducing the annular. area at a circle intersecting
the spacer
member to an area less than the circular area of the bottom mouth. That is the
spacer members are merely supports to hold the nozzle surface spaced from the
floor or base and are not intended to guide liquid flow.
Thus the arrangement as described hereinafter provides a new pump
suction device. The device as described may have one or more of the following
features and advantages:
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It is a round device that sits on the bottom surface to be pumped. It has
a large surface area in comparison with the mouth of the pipe and sits very
close to
the surface.
Because the device sits very close to the surface, it acts as a strainer
and prevents debris from entering the pump suction. The debris cannot fit into
the
gap between the device and the floor.
The flow path through the device is carefully designed to reduce the
fluid velocity at the edges of the device. The fluid velocity creates fluid
friction, and
the pressure drop created is proportional to the friction so that a lower
velocity
provides less pressure drop and less flow reduction. The suction line for any
given
pump size has a fixed Pump Total Flow Area (TFA) which this is the cross
sectional
area of the pump suction line. The TFA for a pump is determined by the size of
the
suction. In this device the TFA is held constant through the device from the
annular
gap through the bottom mouth, such that the flow area between the floor and
the
device is the same as the pump suction TFA at annular gap defined by the
nozzle
profile. The device extends beyond the annular gap to the outer periphery, and
as it
extends out, the flow area of the gap increases with the radius. This increase
in gap
flow area results in a proportional decrease in fluid velocity thus the fluid
enters the
gap at the edge of the device at a slow speed. It accelerates towards the
center of
the device. When it reaches the annular gap at the outer edge of the nozzle
profile,
it will reach constant speed. It will then maintain the constant speed through
the
nozzle area and the pump suction tube and suction hose (all the way to the
pump).
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The pump works by reducing the pressure at the suction. This
reduced pressure causes the fluid to flow to the pump. By increasing the flow
area
at the outside edge of the gap (above the TFA), this device reduces the unit
pressure drop at the outside edge of the nozzle. This is why the velocity of
the fluid
into the edge of the device is lower than the velocity through the suction
hose. This
low velocity reduces the pump suction so as to reduce the possibility of air
breakthrough and is a key feature in allowing the device to lower the fluid
level as
close to the floor as is possible.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the invention will now be described in conjunction
with the accompanying drawings in which:
Figure 1 is an isometric view of a nozzle according to the present
invention.
Figure 2 is a vertical cross sectional view of the nozzle of Figure 1.
Figure 3 is a bottom plan view of the nozzle of Figure 1.
In the drawings like characters of reference indicate corresponding
parts in the different figures.
DETAILED DESCRIPTION
The embodiment of the intake nozzle 10 shown in the drawings is
arranged to sit on a flat surface 13 to remove liquid from the surface by the
suction
of the pump 14 which has an intake line 15 connected by a coupling 16 to the
nozzle.
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The nozzle comprises a cylindrical duct portion 11 and a plate member
17 surrounding the duct portion, The duct portion stands vertically upwardly
and
defines a circular bottom mouth 12 surrounding a central upstanding axis 12A
of the
duct portion and a circular upper end 12B which connects to the circular pipe
15 with
a common inner diameter through the connection and to the pump.
The bottom mouth 12 faces downwardly toward the upwardly facing
flat surface 13 from which liquid is to be drawn into the mouth.
The plate member 17 surrounding the bottom mouth and defines a
downwardly facing nozzle surface 18 facing the flat surface 13, so that the
liquid is
drawn between the flat surface and the downwardly facing nozzle surface to
flow
inwardly from an outer edge 19 of the plate member before entering the bottom
mouth 12.
The surface 18 is supported from the surface 13 by a plurality of
spacer members 20 extending downwardly from the nozzle surface arranged at a
height for spacing the nozzle surface from the flat surface by a predetermined
required distance. The spaced members are small in relation to the area of the
bottom surface 18 so as to avoid interfering with flow through the gap and can
be
located at any suitable location at or adjacent the peripheral edge 19.
The nozzle surface 18 forms a flat annular portion 18A from the edge
19 to an inner edge 18B of the flat portion surrounding the bottom mouth 12
which is
spaced outwardly of the mouth.
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The nozzle surface 18 is shaped between the edge 18B and the mouth
12 so as to define an inwardly and upwardly extending surface portion 18C
which is
smoothly curved upwardly and inwardly to the mouth 12.
The nozzle surface 18 defines an annular gap 18D at the edge 18B
extending from the nozzle surface to the flat surface which defines an annular
area
Al at the annular gap 18D as defined by the height of the gap 18D multiplied
by the
circumference of the circle at the gap 18D. This area Al is arranged to be
substantially equal to the circular area A2 of the bottom mouth, which is
equal to the
area of the intake pipe 15.
The portion 18C of the nozzle surface 18 is shaped such that the
annular area Al defined vertically between the nozzle surface 18C and the flat
surface 13 at any circle surrounding the central axis 12A of the bottom mouth
is
substantially equal to the area Al. Thus the area of the annular gap remains
constant from the gap 18D through to the mouth 12. The mathematical shape of
the
curved surface to achieve this condition can be readily calculated or designed
and
typically a curve known as a 'power law' curve or a 'radial distribution' can
achieve
this condition.
The plate member extends outwardly from the annular gap 18D at the
inner edge 18C of the flat portion 18A to the outer peripheral edge 19 of the
nozzle
surface so as to define a peripheral intake mouth 19A between the flat surface
13
and the outer edge 19 of through which the liquid is drawn to pass under the
nozzle
surface to the bottom mouth. This gap acts as a strainer or filter to prevent
the entry
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of over-size debris into the mouth 12 which could interfere with the operation
of the
pump.
Of course it will be appreciated that the flat nozzle surface, as it
extends outwardly from the annular gap 18D to the peripheral mouth 19, the
annular
5 area at any circle surrounding the central axis increases with the radius.
In this way
the velocity of the liquid entering the gap 19 is at its slowest and it
gradually
increases to the gap 18D, from which the velocity remains constant through the
mouth 12 and the pipe to the pump.
As the plate member is relatively large compared with the mouth 12,
10 the outer peripheral edge .19 is located at a diameter which is at least
double the
diameter at the annular gap 18D.
Also the annular gap 18D is located at a diameter which is at least
double the diameter of the bottom mouth 12.
The spacer members 20 are located at positions spaced outwardly of
the annular gap 18D so that they do not interfere with the flow in the
constant
velocity area between the gap 18D and the mouth 12. They are sufficiently
small
that they avoid reducing the annular area A3 at a circle 18F intersecting the
spacer
members to an area less than the circular area Al of the bottom mouth and
preferably the area A3 is much greater than the area Al so that the velocity
is slow
as the liquid passes the spacer members 20.
Since various modifications can be made in my invention as herein
above described, and many apparently widely different embodiments of same made
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within the spirit and scope of the claims without department from such spirit
and
scope, it is intended that all matter contained in the accompanying
specification shall
be interpreted as illustrative only and not in a limiting sense.
