Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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MULTI-PORT ORIFICE METER FITTING
FIELD OF THE INVENTION:
The present invention relates generally to orifice meters and more
specifically to a multi-port orifice meter.
BACKGROUND OF THE INVENTION:
It is often desirable to calculate the flow rate of a fluid traveling
through a pipe. The method commonly used to determine the flow rate
involves increasing the velocity of flow by causing the fluid to flow through
a
constriction. This results in an increase in the kinetic energy of flow
accompanied by a corresponding drop in pressure at the constriction. The
actual rate of flow can then be calculated by measuring the pressure before
and after the constriction and applying the proper equations.
Of the devices used to determine flow rates, orifice meters have the
simplest design, generally comprising an orifice plate which has a circular
hole concentric with the pipe clamped between two pipe flanges. However,
one circular hole may not be able to measure the flow rate in all cases. In
order to get an accurate measurement in this instance, the flow of the fluid
in
the pipe must be stopped, the orifice plate removed and a new orifice plate
having a circular hole of a different diameter inserted. Not only is this
process
cumbersome and time consuming, there is also considerable risk of injury to
the operator who may inadvertently contact residual fluid in the pipes, which
may be toxic, during the process of changing orifice plates. The present
invention overcomes this deficiency by providing means for changing orifice
plates without having to loosen or remove any part of the fitting.
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SUMMARY OF THE INVENTION
According to a first aspect of the invention, there is provided an
orifice meter comprising: a body comprising a first plate, a second plate
parallel to
the first plate, a peripheral side wall extending from the first plate to the
second
plate to enclose an internal chamber, an inlet port through the first plate
and
communicating with the chamber and an outlet port through the second plate and
communicating with the chamber, the body having a centre axis and the inlet
port
and the outlet port being on opposite sides of the chamber and being at a
common
radial distance from the centre axis, the inlet port and the outlet port being
aligned
with one another; a rotor enclosed completely in the chamber such that the
rotor is
completely enclosed within the body between the inlet port and the outlet
port;
means mounting the rotor within the chamber for rotation about the center axis
of
the body; a plurality of metering orifices through the rotor at said radial
distance
from the center axis; means for selectively rotating the rotor so that each of
the
metering orifices can be selectively aligned with the inlet port and the
outlet port; a
removable plug on the body for accessing the chamber to replace or service the
orifice plates; transducer ports in fluid connection with the inlet port and
the outlet
port; and pressure transducers in the transducer ports for measuring a
pressure
drop across a metering orifice aligned between the inlet port and the outlet
port.
According to a second aspect of the invention, there is provided an
orifice meter comprising: a body comprising a first plate, a second plate
parallel to
the first plate, a peripheral side wall extending from the first plate to the
second
plate to enclose an internal chamber, an inlet port through the first plate
and
communicating with the chamber and an outlet port through the second plate and
communicating with the chamber, the body having a centre axis and the inlet
port
and the outlet port being on opposite sides of the chamber and being at a
common
radial distance from the centre axis, the inlet port and the outlet port being
aligned
with one another; a rotor enclosed completely in the chamber such that the
rotor is
completely enclosed within the body between the inlet port and the outlet
port;
means mounting the rotor within the chamber for rotation about the center axis
of
the body; a plurality of metering orifices through the rotor at said
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radial distance from the center axis; means for selectively rotating the rotor
so that
each of the metering orifices can be selectively aligned with the inlet port
and the
outlet port; an access aperture on a side of the body at said radial distance
from
the centre axis for removing metering orifices without removing the rotor from
the
body; and a removable plug arranged to be fitted into the access aperture for
sealing the body.
According to a third aspect of the invention, there is provided an
orifice meter comprising: a body comprising a first plate, a second plate
parallel to
the first plate, a peripheral side wall extending from the first plate to the
second
plate to enclose an internal chamber, an inlet port through the first plate
and
communicating with the chamber and an outlet port through the second plate and
communicating with the chamber, the body having a centre axis and the inlet
port
and the outlet port being on opposite sides of the chamber and being at a
common
radial distance from the centre axis, the inlet port and the outlet port being
aligned
with one another; a rotor enclosed completely in the chamber such that the
rotor is
completely enclosed within the body between the inlet port and the outlet
port;
means mounting the rotor within the chamber for rotation about the center axis
of
the body; a plurality of metering orifices through the rotor at said radial
distance
from the center axis; means for selectively rotating the rotor so that each of
the
metering orifices can be selectively aligned with the inlet port and the
outlet port; a
removable plug on the body for accessing the chamber to replace or service the
orifice plates; an inlet orifice compression ring mounted on the first plate
around
the inlet port for forming a tight seal between the inlet port and the rotor;
and an
outlet orifice compression ring mounted on the second plate around the outlet
port
for forming a tight seal befinreen the outlet port and the rotor.
Clearly, the above-described orifice meter represents an
improvement over the prior art. Once connected, the pressure transducers
measure the pressure at the inlet and outlet ports. The difference in the
pressures
is then used to calculate the flow rate. However, in the event that the flow
rate
cannot be determined with these values, the stem extending outside the orifice
meter body is used to rotate the metering orifices so that a different orifice
plate is
aligned with the inlet and outlet ports. At this point, the differential
pressure is
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determined again. If necessary, the plug can be removed for easy access to the
orifice plates for service or replacement. Furthermore, all of this is
accomplished
quickly and easily, without having to stop the flow of the fluid, disconnect
the orifice
meter, connect the replacement orifice meter and then restart the flow of the
fluid.
Thus, not only does the above-described invention represent considerable
savings
in time and effort, there is also virtually no risk of injury to the operator,
as the
orifice plate can be changed simply by turning the stem extending from the
orifice
meter body. Furthermore, as the plug allows direct access to the metering
orifices
and the interior of the orifice meter body, the orifice meter does not have to
be
disconnected in order to service or replace the orifice plates.
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DESCRIPTION OF THE FIGURES:
Figure 1 is an exploded view of the orifice meter.
Figure 2 is a schematic representation of the orifice meter.
DETAILED DESCRIPTION:
In one embodiment, the orifice meter 1 comprises an inlet flange 10, an
outlet flange 11, a center assembly 23 and a rotor 28, the details of which
are shown in Figure 1.
The inlet flange 10 and the outlet flange 11 comprise disks of identical
size and shape, designated inlet disk 12 and outlet disk 13. Both disks
include
a transducer port 14 for a pressure transducer 15 arranged within the interior
of the disks 12, 13. The details of the pressure transducers 15 are not shown
as these will be well-known to one skilled in the art. The disks 12, 13 have a
plurality of connecting apertures 16 passing through the entire width of the
disk, located at a common radial distance from the center and evenly spaced
proximal to the outer edge of the respective disks 12, 13. Additionally, the
disks 12, 13 include ports, designated as inlet port 17 and outlet port 18,
for
connection to a pipe as described below. The ports 17, 18 are at a common
radial distance from the center 19, 20 of the respective disks 12, 13 so that
the ports 17, 18 are aligned when the orifice meter 1 is assembled as
described below. Located within each of the ports 17, 18 is an orifice
compression ring 35 for farming a tight seal between the orifice meter 1 and
the ends of the pipe as described below. Furthermore, the inlet disk 12
includes a shaft aperture 21 passing through the center 19 of the inlet disk
12 for passing a shaft therethrough as described below. The outlet disk 13
includes an access aperture 22 at the same radial distance from the center 20
of the outlet disk 13 as the outlet port 13. The functions of the shaft
aperture
21 and the access aperture 22 do not depend on location, meaning that
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either or both can be located on the inlet flange 10 or the outlet flange 11
as
desired.
The center assembly 23 comprises an open ring 24 having the same
diameter as the inlet disk 12 and the inlet disk 13 described above.
S Furthermore, the open ring 24 has a plurality of connecting apertures 25
passing through the entire width of the open ring 24 shaped and located at
the same radial distance from the center 26 of the open ring 24 as the
connecting apertures 16 in the disks 12, 13 described above, evenly spaced
proximal to the outer edge of the open ring 24. These connecting apertures
16, 25 are involved in the assembly of the orifice meter 1 as described
below. The open ring 24 has an inner surface 27 that is arranged for
mounting the rotor 28 therewithin as described below.
The rotor 28 comprises a circular plate holder 29 having a center 30
and a shaft 31 connected to the circular plate holder 29 so as to pass
through the center 30 of the circular plate holder 29. Of note is that the
circular plate holder 29 is of approximately the same diameter as the open
area within the open ring 24 such that the rotor 28 can be mounted for
rotation within the open ring 24 as described below. The circular plate holder
29 includes a plurality of orifice apertures 32 evenly spaced around the
circular plate holder 29 and located at a common radial distance from the
center 30 of the circular plate holder 29. Located within each of the orifice
apertures 32 is an orifice plate 33 surrounded by an O-ring 34 of a diameter
slightly less than the diameter of the orifice apertures 32. Thus, the O-ring
34
forms a seal between the orifice plate 33 and the orifice aperture 32. Of note
is that the orifice plates 33 may have openings of various diameters and are
removably mounted within the orifice apertures 32.
Assembled, the rotor 28 is mounted into the inner ring 24 of the center
assembly 23 such that the outer edge of the circular plate holder 29 engages
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the inner surface 27 of the open ring 24 so that the rotor 28 is able to
rotate
freely within the open ring 24. Next, the shaft 31 of the rotor 28 is passed
through the shaft aperture 21 until the center assembly 23 and the inlet
flange 10 are in direct contact. The outlet flange 11 is then placed into
direct
contact with the center assembly 23 such that the centers of the inlet disk
19, the center assembly 26 and the outlet disk 20 are aligned, forming an
orifice meter 1 with a center axis. Of note is that the end of the shaft 31
that
is not connected to the circular plate holder 29 extends outward from the
orifice meter 1 so that the rotor 28 within the orifice meter 1 can be rotated
from the exterior of the orifice meter 1 by turning the shaft 31. Because the
ports 17, 18 and the orifice apertures 32 are located at a common radial
distance from their respective centers and the centers are aligned, it is
possible to align the ports 17, 18 with one another and with one of the
orifice
apertures 32. At this point, the orifice compression rings 35 within the inlet
port 17 and the outlet port 18 each interact with one side of the O-ring 34,
thereby forming a tight seal. Similarly, the connecting apertures 16 in the
inlet flange 10 and the outlet flange 11 and the connecting apertures 25 in
the center assembly 23 are aligned and bolts are passed therethrough. The
access aperture 22 is at the same radial distance from the center axis as the
orifice apertures 32 and is positioned so that it is aligned with one of the
orifice apertures not aligned with the ports 17, 18. Thus, the orifice plates
33
and O-rings 34 can be serviced or replaced from the access aperture 22
without the need to disconnect the orifice meter 1. A removable plug 36
including seals and sized and shaped to conform with the size and shape of
the access aperture 22 is fastened into the access aperture 22 with cap
screws, thereby sealing the access aperture 22. Finally, a selector disk 37 is
placed over the end of the shaft 31 that extends from the orifice meter 1, and
a disk or a collar is fastened to the shaft 31, thereby locking the shaft 31
into
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place. The selector disk 37 includes numbered positions arranged on its
surface that correspond to the positions of the orifice apertures 32 on the
circular plate holder 29 of the rotor 28 so that turning the shaft 31 from
outside the orifice meter 1 to a numbered position on the surface of the
selector disk 37 brings the corresponding orifice aperture 32 into alignment
with the ports 17, 18.
In operation, the ports 17, 18 of the orifice meter 1 are connected to a
pipe 38 as shown in Figure 2. The shaft 31 is turned to the desired position
on the selector disk 37 so that the circular plate holder 29 of the rotor 28
rotates to bring the desired orifice plate 33 into alignment with the ports
17,
18 so that a fluid can flow therethrough. The fluid flows down the pipe 38
and into the inlet port 17. At this point, the pressure is measured by the
pressure transducer 15 in the transducer port 14 of the inlet flange 10. The
fluid then flows through the orifice aperture 32 and the flow is constricted
by
the selected orifice plate 33. This causes an increase in the kinetic energy
of
the flow and a decrease in pressure. Next, the fluid passes into the outlet
port 18 where the pressure is measured by the pressure transducer 15 at the
transducer port 14 of the outlet flange 11. The difference in pressure in the
inlet flange 10 and the outlet flange 11 is used to determine the rate of
flow.
If necessary, a different orifice plate 33 can be rotated into alignment with
the inlet port 17 and the outlet port 18 and the rate of flow measured again
without disconnecting the orifice meter 1. If desired, the removable plug 36
can be removed and the orifice plate 33 in the circular plate holder 29
aligned
with the access aperture 22 can be replaced without disconnecting the orifice
meter 1. Thus, the above-described invention makes it possible to change or
even replace orifice plates 33 quickly and easily without having to loosen any
part of the fitting or disconnect the orifice meter 1.
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Since various modifications can be made in my invention as herein
above described, and many apparently widely different embodiments of same
made within the spirit and scope of the claims without departing 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.
