Dual chamber orifice fitting

A dual chamber orifice fitting comprising a first chamber maintained in fluid communication with a pipeline, a fluid flowing in the pipeline passing through the first chamber; a second chamber selectively maintained in fluid communication with the first chamber; a sealing member selectively rotatable from a first position wherein the sealing member seals the first chamber from the second chamber, and a second position wherein the sealing member permits the first chamber to be placed in fluid communication with the second chamber.

BACKGROUND OF THE INVENTION 
This invention relates generally to a flow measurement device and more 
particularly to a dual chamber orifice fitting comprising a flow 
measurement device using an orifice plate which measures and utilizes 
differential pressure as a basis of flow measurement. While such orifice 
fittings and orifice plates have taken various forms, they have 
encountered a number of problems, including a requirement of high 
maintenance, the possibility of operator error, and complicated individual 
apparatuses to perform the function required. 
Generally, pipelines are used to transport fluids, including but not 
limited to oil and gas from wells. In order to measure the flow rate of 
these fluids in the pipeline, orifice plates are installed in a special 
fitting, or orifice plate carrier, and are thereafter installed in-line 
within the pipeline sections. When placed within the pipeline and in the 
fluid flow path, the orifice plates somewhat restricts the flow. 
Thereafter, a flow pressure differential develops between the flow on the 
upstream and downstream side of the orifice plate. Based on this 
measurement, and the comparison of the cross-sectional area of the 
pipeline to the cross-sectional area of the smaller through hole formed in 
the orifice plate, the flow rate of the fluid can be determined. 
In many pipelines which must have their flow measured, it is very expensive 
or time consuming to shut down the pipeline to change the orifice plate, 
or make other required repairs thereto. Since the orifice plate must be 
placed within the pipeline in order to measure the flow of the fluid, it 
has been found to be beneficial to allow for the removal and replacement 
of such orifice plates without depressurizing the flow of fluid, and 
emptying the pipeline. Therefore, while early orifice plates have been 
situated within the pipes, and have required the shutdown of the pipe in 
order to change orifice plates, more recently, systems have been designed 
to allow for the insertion and removal of orifice plates in the pipeline 
without interrupting flow of the fluid therethrough. 
In order to properly employ such a system which allows for the insertion 
and removal of such an orifice plate without interrupting the flow of the 
fluid, a number of features in the system are required. First, it is 
necessary to have a first chamber which encompasses the fluid flow path 
through the pipeline and second chamber, selectively spaced apart from the 
first chamber, which does not encompass the fluid flow path through the 
pipeline. These chambers must be selectively maintained either in fluid 
communication with each other or sealed from each other, and must be 
maintained in a fluid tight state even under high pressure as applied by 
the fluid flow in a pipeline. The system must allow for the movement of 
the orifice plate from the pipeline and first chamber, into the second 
chamber which can thereafter be separated from the first chamber by a 
fluid tight seal, and thereafter opened so that the orifice plate may be 
replaced, repaired or simply removed. Such systems have been well known in 
the art, and are shown in U.S. Pat. No. 5,318,073 (Kendrick, et al.) and 
any number of "senior" orifice fittings (senior referring to a dual 
chamber system), as are produced by Daniel, Perry Equipment Corporation 
and various other manufacturers. 
As noted above, each of these apparatuses work with the requirement of a 
fluid tight seal between a first chamber, which is in fluid communication 
with the pipeline and encompasses the fluid flow path of the pipeline, and 
a second chamber which may be placed selectively in and out of fluid 
communication therewith. In order to achieve such a seal, prior art dual 
chamber orifice fittings rely on a sliding valve which requires the 
addition of grease or other sealing fluid thereto in order to insure that 
the valve slides properly and forms a fluid tight seal when closed. Such a 
sealing member is shown as closing valve V in U.S. Pat. No. 4,014,366 
(Critendon). This patent describes a sliding valve fitting as is used in 
the prior art, whereby a sliding valve plug portion contains teeth on a 
portion thereof, which are meshed with a gear and rotating handle, or 
other automatic rotation device. By rotating this handle or device, the 
user moves the sliding valve plug portion against the passage between the 
first and second chambers, and thereby seals the second chamber from the 
first chamber. However, devices utilizing such a sliding mechanism has 
suffered from a number of defects. 
First, the time required to move such a valve portion into position is 
great. Additionally, such a device utilizes a plurality of gears, racks 
and pinions complicating the device and requires the regular insertion of 
grease or other sealing fluid into the apparatus in order to preserve a 
fluid tight seal between the sliding valve plug mechanism and the casing 
forming the passage between the first and second chambers. Finally, since 
such a sliding valve plug device requires the determination by an operator 
whether the required fluid tight seal has been formed, and whether the 
sliding valve plug portion has been moved into its proper position, it is 
possible that the fluid flow could be released before the seal has been 
formed, thereby allowing fluid under pressure from the pipeline to escape 
and thereby not be contained within the pipeline or fitting causing a 
potentially dangerous situation. Therefore, it would be beneficial to 
provide a valve mechanism for sealing between a first and second chamber 
of a dual chamber orifice fitting which could be moved into place quickly, 
which does not require any insertion of grease or other lubrication 
substance, and which is simple in design and is automatically placed into 
the proper position to seal the chamber so that fluid cannot escape. 
Additionally, it would be beneficial to provide a safety locking mechanism 
so that the valve mechanism could not be moved from its sealed position 
accidentally. 
The accuracy of the measurement given by the dual chamber orifice fitting 
depends on a large number of factors, including, as noted above, the ratio 
of the cross-sectional area of the through hole formed in the orifice 
plate to the cross-sectional area of the pipeline through which the fluid 
is flowing, and additionally the centering of the through hole formed in 
the orifice plate with the fluid flow path, and the leakage of any fluid 
around the orifice plate which does not flow through the through hole 
formed in the orifice plate. 
Thus, to ensure that the orifice plate properly measures the fluid flowing 
in the pipeline, it is necessary to ensure that all of the fluid flowing 
through the pipeline is directed through the through hole formed in the 
orifice plate and that none is allowed to flow through the pipeline 
without passing through this through hole in the orifice plate. It is also 
necessary to insure that the seal holding the orifice plate remain fluid 
tight, thereby not allowing any fluid to flow through the pipeline other 
than through the through hole formed in the orifice plate. Such a seal 
member for an orifice plate is shown in U.S. Pat. No. 5,318,073 issued to 
Kendrick, et al., wherein a seal member is shown which extends on the 
upper and lower surface of an orifice plate, in order to ensure that the 
orifice plate is maintained in contact with solid portions of the pipe so 
as to ensure that fluid does not flow therebetween. While such a design 
has been somewhat satisfactory, such a design is most effective upon 
proper placement of the seal within the chamber in the pipe. 
However, during insertion of the orifice plate while the fluid is flowing 
through the pipe, it is possible that the seal member could be improperly 
deformed due to the downward movement of the orifice plate and seal member 
through the laterally moving fluid in the pipeline. If improperly 
deformed, it is possible that the seal will not be properly seated, and 
therefore will allow water to pass between the seal and the orifice plate, 
and not direct all of the fluid through the through hole formed in the 
orifice plate, thereby affecting the accuracy of any fluid flow 
measurement. Therefore, it would also be beneficial to provide a seal 
member for an orifice plate which will not improperly deform when the 
orifice plate is inserted into a pipe under pressurized fluid conditions 
and which would therefore properly seal the orifice plate to the pipeline 
and increase the accuracy of measurement of fluid flow. 
Finally, a further requirement of proper fluid flow measurement is that the 
through hole formed in the orifice plate through which the fluid is 
directed must remain properly centered in the pipeline and in the fluid 
flow path. However, since the orifice plate is being inserted into the 
pipeline and the fluid flow path under pressure, it is possible that the 
orifice plate might not be precisely centered within the fluid flow path. 
This off-center positioning may result in inaccurate measurement of fluid 
flow rates. Therefore, it would further be desirable to provide an orifice 
plate whose position can easily be adjusted while the orifice plate 
remains within the carrier plate. 
In prior art dual chamber orifice fittings, the second, or upper, chamber 
is formed with two selectively openable valves. The first is an 
equalization valve. The use of this valve allows for the equalization of 
pressure between the first and second chamber, thereby allowing fluid into 
the second chamber, without removing the seal between the first and second 
chambers. The second, is a bleeding, or evacuation valve whereby after the 
orifice plate is moved from the first chamber to the second chamber, and 
the seal between the first chamber and the second chamber is replaced, the 
fluid maintained within the second chamber is evacuated in order to reduce 
the pressure therein. While the prior art devices utilize two valves for 
this purpose, it is possible, through operator error, to open both valves 
at the same time, thereby allowing material to flow under high pressure 
from the first chamber into the second chamber, and to be forced out the 
evacuation valve, thereby causing a potentially dangerous situation. 
Therefore, it would be desirable to provide a system whereby it is not 
possible for there to be communication between the first and second 
chambers, and between the second chamber and external atmosphere at the 
same time. 
SUMMARY OF THE INVENTION 
Generally speaking, in accordance with the invention, a dual chamber 
orifice fitting is provided for measuring fluid flow in a pipeline, and 
which allows for the change of the orifice plate employed therein which 
measures the fluid flow without the depressurization of the pipeline, and 
without the turning off of fluid flow therein. First, an apparatus is 
provided whereby an eccentric plug valve is provided for sealing between a 
first and second chamber in the apparatus. The eccentric plug is 
selectively moveable from a first position wherein the plug seals the 
passage between the first and second chambers, to a second position 
whereby the first and second chambers are placed in fluid communication 
with each other. The movement of the plug from the first to the second 
position is achieved by the rotation, either mechanically or 
automatically, of a rotational positioning arm which is geared in order to 
perform this movement. 
In a preferred embodiment, a safety locking mechanism is provided on the 
rotational positioning arm so as to ensure that the movement of the seal 
from the first position to the second position is not initiated in error. 
Specifically, this will ensure that the second chamber is not open to the 
exterior when the seal between the first and second chambers is opened. 
Specifically, a circular through hole is formed in an orifice plate carrier 
which has a further raised collar portion. An orifice plate seal has an 
upper portion having an upper diameter and a lower portion having a lower 
diameter, the lower diameter being slightly greater than that of the upper 
diameter. Thus the orifice plate seals forms an outer circumferential edge 
at an angle where the larger lower diameter meets the upper smaller 
diameter. This angle is mirrored by a similar angle on the inner edge of 
the raised collar portion of the orifice plate carrier and raised collar 
portion thereof. Thus, the orifice plate seal is slightly compressed and 
placed into the orifice plate, the angled circumferential edge engaging 
the angled inner edge of the raised collar portion of the orifice plate 
carrier. The orifice plate seal is disposed within the orifice facing 
upstream to the fluid flow within the pipe so that the fluid flowing in 
the pipeline will further ensure contact between orifice plate carrier and 
the orifice plate seal, and any upward or downward motion of the orifice 
plate carrier will not cause the orifice plate seal to be separated from 
the orifice plate carrier or the orifice plate because of the angled outer 
circumferential portion of the orifice plate seal member. 
Additionally, adjustment pins are provided in the body of the lower chamber 
and are designed to maintain contact with the raised collar portion of the 
orifice plate carrier when the orifice plate carrier is inserted into the 
pipeline and fluid flow path. These adjustment pins allow for movement of 
the orifice plate carrier and the orifice plate so that the orifice plate 
may be properly centered in the fluid flow path. This centering may be 
performed while the orifice plate is maintained within the pipeline, and 
under high pressure fluid flow conditions. Either two pins or three pins 
may be provided, depending on the desired degree of flexibility in 
determining the actual position of the orifice plate. 
In another embodiment, an L-port valve is provided to selectively isolate 
the first chamber from the second chamber, whereby a single valve is 
selectively positionable in three positions. The valve is formed having an 
"L" shape and is seated in a "T" shaped valve seat, the valve seat 
separating the first chamber from the second chamber and the second 
chamber from ambient air. When the port is in the first position the first 
and second chambers are placed in fluid communication, thereby equalizing 
the pressure within said first and second chambers. In the second 
position, the evacuation position, the fluid is evacuated from the second 
chamber, after the seal is replaced between the first and second chambers. 
Finally, in the third position, the block position, both the passage 
between said first and second chamber, and the evacuation passage are 
blocked, thereby ensuring fluid tight sealing of both the first and second 
chambers, and also the seal between the first and second chambers. Since a 
single valve is used, it is not possible for the passage between the first 
and second chambers, and the evacuation chamber to be open at the same 
time, and thereby a potentially dangerous situation is averted. 
Accordingly, it is an object of the invention to provide an improved dual 
chamber orifice fitting capable of measuring the flow of a fluid through a 
pipeline in a highly accurate manner. 
Another object of the invention is to provide an improved dual chamber 
orifice fitting that allows for simple and secure sealing and opening of a 
passage between a first and second chamber in the orifice fitting. 
A further object of the invention is to provide an improved dual chamber 
orifice fitting in which an eccentric valve plug is used to seal the 
passage between the first and second chambers in the orifice fitting so 
that fluid is maintained within the proper chamber and in the pipeline. 
Another object of the invention is to provide an orifice plate carrier, 
orifice plate seal and orifice plate which ensure that fluid flowing in a 
pipeline is directed through the through hole formed in the orifice plate. 
Still a further object of the invention is to provide an orifice plate seal 
with an angled outer circumference so that during upward and downward 
movement of the plate seal member through a laterally flowing fluid in a 
pipeline, the orifice plate seal member is not deformed, and no fluid 
passes around the outside of the orifice seal member. 
Yet another object of the invention is to provide adjustment pins for 
adjusting the positioning of the orifice plate. 
A still further object of the invention is to provide an improved dual 
chamber orifice fitting, which has an orifice plate, with pins for 
adjusting the positioning of the through hole formed in the orifice plate, 
the adjustment pins being adjustable while the orifice plate is in proper 
placement within the pipeline, and under high fluid flow pressure. 
Another object of the invention is to provide an improved dual chamber 
orifice fitting employing a valve which is selectively positionable 
between at least a first position providing fluid communication between a 
first and second chamber, a second position providing evacuation of the 
second chamber, and a third position sealing the first and second chambers 
from each other. 
Still other objects and advantages of the invention will in part be obvious 
and will in part be apparent from the specifications and drawings. 
The invention accordingly comprises the features of construction, 
combinations of elements, an arrangement of parts which will be 
exemplified in the constructions hereinafter set forth and the scope of 
the invention will be indicated in the claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Reference is first made to FIGS. 1 and 2 which depict a dual chamber 
orifice fitting 10 constructed in accordance with a first embodiment of 
the invention. Dual chamber orifice fitting 10 includes an inlet 21 for 
receiving fluid flow from a pipe. A flange 22 formed on a front side of 
orifice fitting 10 about inlet 21 is used to bolt orifice fitting 10 to a 
section of a pipeline, which is not shown. Flange 22 is further formed 
with bolt holes 23 which are included for this purpose. Alternatively, 
flange 22 may include weld bevels (not shown) thereby allowing flange 22 
to be welded directly to the pipeline. Additionally, a combination of 
welding and bolt holes using bolts (not shown) may also be employed to 
secure fitting 10 to the pipeline. An outlet 24 is situated on a back side 
of dual chamber orifice fitting 10 opposite flange 22, to which the 
pipeline is attached, and which allows for the fluid flowing through the 
pipeline and orifice fitting to exit the fitting, thus returning the fluid 
to the pipeline. 
Dual chamber orifice fitting 10 is further formed with a first lower 
chamber and a second upper chamber 40. As known in the art upper chamber 
40 is affixed to lower chamber 20 by bolts 42, or the like. As is 
discussed further below, the first lower chamber 20 comprises a portion of 
dual chamber orifice fitting 10 which operates as part of the pipeline, 
and in which an orifice plate 65 (described below) is retained during use. 
Furthermore, second upper chamber 40 is a portion of dual chamber orifice 
fitting to which orifice plate 65 is moved when it is to be changed or 
repaired, thereby separating orifice plate 65 from the fluid flow. First 
lower chamber 20 is further formed with a rod positioning sleeve 25 which 
allows dual chamber orifice fitting 10 to be supported by a rod or the 
like passed through and retained by rod positioning sleeve 25. 
Now making reference to FIG. 3 as well, lower chamber 20 includes a support 
surface 26 having an opening 34 therein for supporting upper chamber 40 in 
a meeting relationship. Bolt holes 27 are formed in support surface 26 for 
receiving retaining bolts 42. A cavity 28 is formed in lower chamber 20 
and a slit 29 is formed to provide a passageway between cavity 28 and a 
flow passage 30 (FIG. 4) formed between inlet 21 and outlet 24. Opening 
31b and symmetrical outlet 31a (not shown) are disposed coaxially to each 
other in sides of lower chamber 20. A cover 32 is mounted to lower chamber 
20 at opening 31a and a gland retainer 33 is mounted to lower chamber 20 
at opening 31b. 
Reference is again made to FIG. 3, which depicts an exploded view of dual 
chamber orifice fitting 10, wherein first lower chamber 20 and second 
upper chamber 40 have been separated from each other. First lower chamber 
20 is provided with an eccentric plug member 80, a rotational movement rod 
62 and adjustment pins 75, in addition to the elements previously 
described, each of which will be discussed in detail below. 
As is shown in FIGS. 4 and 6, second upper chamber 40 is formed independent 
of first lower chamber 20, but during use is maintained in intimate 
contact therewith through the fixing of second upper chamber onto first 
lower chamber through the use of attachment bolts 42. These chambers are 
situated relative to each other so that communication path 35 is aligned 
in the two chambers, and a continuous communication path 35 is formed 
therethrough. 
Referring to FIGS. 4 and 6, second upper chamber 40 is further formed of a 
body portion 48, the top of which is sealed by an upper retaining member 
46 and a retaining fitting 46a, both of which are retained against body 
portion 48 by retaining bolts 47 to seal cavity 56 at the top thereof. 
Retaining bolts 47, upper retaining member 46 and retaining fitting 46a 
are selectively removable to allow access to cavity 56 of second upper 
chamber 40. A plate movement rod 44 having gears 45 thereon is rotatably 
mounted within cavity 56. Plate movement rod 44 may be rotated after 
engagement of gear rachet 63 with parallel gear racks 66 and 67 (FIG. 2) 
of orifice plate 60 (described hereinafter) in order to further move 
orifice plate 60 in the vertical direction, and also to move orifice plate 
60 out from body portion 48 of second upper chamber 40 when required, 
after retaining bolts 47, upper retaining member 46 and retaining fitting 
46a have been removed. 
As is shown in FIGS. 2 and 3 and more specifically in FIG. 4, second upper 
chamber 40 is formed with a cavity 56 therethrough. A pressure 
equalization channel 53 provides a fluid path between cavity 56 and the 
exterior of chamber 40. A channel 57 provides a pathway between cavity 28 
and the exterior of upper chamber 40. A third channel 58 also extends from 
cavity 56 to the exterior of upper chamber 40. 
Pressure equalization valve 52 disposed within channel 53 and is 
displaceable between a first position in which channel 53 and channel 57 
are closed from each other preventing formation of an equalization path 
between first lower chamber 20 and second upper chamber 40, and a second 
position whereby first lower chamber 20 and second upper chamber 40 are 
placed in fluid communication with each other through a pressure 
equalization path formed by channel 53 and channel 57. 
A sleeve 59 is seated in channel sleeve 58. Sleeve 59 is formed with an 
opening 61, an inlet 78 and a pressure evacuation path 55. A pressure 
evacuation valve 54 seated within sleeve 59 is displaceable between a 
first position, whereby pressure evacuation path 55 communicates with 
inlet 78 placing cavity 56 in fluid communication with ambient air, or 
other evacuation apparatus, and a second position blocking inlet 78 
whereby pressure evacuation path 55 and cavity 56 are not in fluid 
communication with ambient air or the like. 
Eccentric plug member 80 is rotatably mounted within cavity 28 between 
cover 32 and gland retainer 33. Eccentric plug member 80 is specifically 
designed to form a fluid tight seal between first lower chamber 20 and 
second upper chamber 40 when to positioned in its sealing position. 
Eccentric plug member 80 includes a substantially C-shaped portion 84 
having an inner face 83 and outer circumferential face 81. Off center 
rotational support rods 82a, 82b extend from plug portion 84 from either 
end thereof and allow the eccentric rotation of eccentric plug member 80 
within cavity 28. Support rods 82a, 82b are rotatably supported by cover 
32 and gland retainer 33, respectively. Eccentric plug member 80 is 
selectively rotatable from a first position, in which eccentric plug 
member 80 forms a fluid tight seal between first lower chamber 20 and 
second upper chamber 40, and a second position whereby first lower chamber 
20 and second upper chamber 40 are placed in fluid communication through a 
communication path 35 (see FIG. 4). 
In a preferred embodiment, eccentric plug member 80 is formed of a 
rubberized material so as to ensure a proper seal between outer 
circumferential face 81 thereof and radial engaging face 86 of plug 
fitting 85, and which does not require the use of grease or other 
lubricant to allow proper movement thereof. Additionally, grease or other 
sealing fluid is not required to insure a fluid tight seal. 
In order to ensure that eccentric plug member 80 forms a fluid tight seal, 
a plug fitting 85 is mounted to upper chamber 40 about communication path 
35 to engage eccentric plug member 80 when eccentric plug member 80 is in 
the first position. As is more specifically shown in FIGS. 10 and 11, plug 
fitting 85 includes a radial engaging face 86 formed about a slit 89 which 
is dimensioned to engage outer circumferential face 81 of eccentric plug 
member 80 as is more explicitly shown in FIGS. 12-14. Therefore, when 
eccentric plug member 80 is retained in its first or sealing position, 
outer circumferential face 81 thereof is maintained in contact with radial 
engaging face 86 of plug fitting 85, thereby forming a fluid tight seal 
therebetween. The pressure from the fluid flowing through first lower 
chamber 20 imparts a force upon inner face 83 of eccentric plug member 80, 
thereby further aiding the maintenance of a fluid tight seal. 
Dual chamber orifice fitting 10 also includes an orifice plate carrier 60. 
An orifice plate 65 is fixed to orifice plate carrier 60 through an 
orifice plate seal 70, all of which are shown in FIG. 3. As is 
additionally shown in FIG. 5, orifice plate carrier 60 further comprises 
parallel gear racks 66 and 67 extending vertically along the outside edge 
of one surface of orifice plate carrier 60. During use, as shown in FIG. 
6, orifice plate carrier 60 is disposed within flow passage 30. Orifice 
plate carrier 60 can be raised and lowered within dual chamber orifice 
fitting 10 by shaft 62 and pinions 63 which mesh with parallel gear racks 
66 and 67 to vertically move orifice plate carrier 60 between a first 
position in flow passage 30 and a second position in cavity 56. Rotation 
of shaft 62 in a first direction moves orifice plate carrier 60 through 
communication path 35. After a predetermined amount of movement in the 
vertical direction, gears 45, mounted in second upper chamber 40, come 
into contact with contact parallel gear racks 66 and 67 and rotate to 
continue the upward movement of orifice plate carrier 60 and its 
associated components into second upper chamber 40 so that orifice plate 
carrier 60 is completely disposed within cavity 56. 
Orifice plate carrier 60 is formed with an opening 71 therethrough to 
receive orifice plate 65 and orifice plate seal member 70 disposed between 
orifice plate 65 and orifice plate carrier 60. As is further shown in 
FIGS. 7-9, orifice plate seal 70 engages the outer circumferential edge of 
orifice plate 65. Orifice plate seal 70 is formed with a planar portion 74 
which is maintained in contact with orifice plate carrier 60. Planar 
portion 74 extends to a bead portion 79 to form a shoulder 84 
therebetween. An angled outer circumferential edge 73 of orifice plate 
seal 70 forms an obtuse angle .theta. with orifice plate carrier 60. 
Orifice plate collar 64 includes an angled interior circumferential edge 
88 which forms an acute angle with orifice plate carrier 60 which is the 
compliment of angle .theta.. 
As is more completely shown in FIG. 8, orifice plate seal 70 is inserted 
into orifice plate carrier 60 after orifice plate 65 has been inserted 
into orifice plate seal 70. The angled outer circumferential edge 73 of 
orifice plate seal 70 engages the interior circumferential edge 88 of a 
collar portion 64 of orifice plate carrier 60, as is shown in FIGS. 17 and 
18, anchoring seal member 70 between shoulder 84 and outer circumferential 
edge 73 to form a substantially fluid tight seal between seal 70 and 
collar 64. As shown in FIG. 8, fluid flows in the direction of arrow F 
through a pipe in which the dual chamber orifice fitting, and in effect 
orifice plate carrier 60, orifice plate 65 and orifice seal 70 have been 
inserted. Orifice plate carrier 60 carries orifice plate 65 on the 
upstream side thereof. Thus, the fluid pressure against orifice plate seal 
70 compresses seal 70 against the inner circumference of collar 64 and 
helps to ensure the fluid tight seal between orifice plate seal 70 and 
orifice plate 65, thereby facilitating all fluid passing through the pipe 
to pass through orifice plate 65. Angled outer circumferential edge 73 of 
orifice plate seal 70 catches angled interior circumferential edge 88 of 
collar portion 64 so that the engagement of orifice plate seal 70 with the 
collar portion 64 of orifice plate carrier 60 ensures that during 
insertion or removal of orifice plate carrier 60, a fluid tight seal is 
maintained between orifice plate 65 and orifice plate carrier 60, thereby 
insuring that fluid does not leak around the edges of orifice plate seal 
70. 
First lower chamber 20 is further provided with adjustment pins 75 for 
adjusting the position of orifice plate carrier 60, or orifice plate 65, 
when in position within first lower chamber 20 and under fluid flow 
conditions. As is shown in FIG. 17, in a first embodiment, adjustment pins 
75 are situated against the outside edge of collar portion 64 which is in 
turn formed integrally with orifice plate carrier 60. In this embodiment, 
two adjustment pins are provided. Also provided is a ball plunger 77 
situated at the top of orifice plate carrier 60 to impart a downward force 
thereon. As shown in FIG. 18, each of pins 75 and plunger 77 imparts a 
force on orifice plate carrier 60, these forces allowing for the fine 
positioning of orifice plate carrier 60. By adjustment of these adjustment 
pins 75, collar portion 64 and orifice plate carrier 60, along with 
orifice plate 65 and orifice plate seal 70 can be moved relative to first 
lower chamber 20. This movement relative to first lower chamber 20 allows 
for fine adjustment of the positioning of the orifice plate carrier 60, 
and thereby allows an operator to properly center orifice plate 65 within 
the fluid flow path. 
As is further shown in FIG. 3, and FIG. 19, adjustment pins 75 are retained 
within the outer wall 120 of first lower chamber 20. When plugs 76, 
disposed within outer wall 120, are removed from first lower chamber 20, 
access may be had to adjustment pins 75 from outside the dual chamber 
orifice fitting 10 while orifice plate carrier 60 and associated hardware 
is within the fluid flow path. Therefore, these adjustments to ensure the 
centering of the opening formed in the orifice plate and, thus the proper 
working of the apparatus, can be made while the apparatus and orifice 
plate 65 are in operation. Adjustment pins 75 are adjusted to move the 
collar portion 64 relative to first lower chamber 20 and therefore orifice 
plate carrier 60 to the left, right and vertically. Therefore, these two 
adjustment pins 75, along with the downward force imparted by ball plunger 
77 allow for adjustment of the positioning of the orifice plate relative 
to the fluid flow as needed. The use of orifice plate carrier 60, orifice 
plate seal 65, orifice plate 70, adjustment pins, and any other associated 
hardware may also be used with a single chamber orifice fitting. 
When it is desirable for the first lower chamber 20 and second upper 
chamber 40 to be placed in fluid communication with each other, eccentric 
plug member 80 may be rotated in the direction of arrow A (FIG. 6) to a 
second position whereby outer circumferential face 81 is removed from 
contact with radial engaging face 86 thereby opening communication path 35 
and placing the two chambers in fluid communication with each other, and 
thus allowing fluid to flow from first lower chamber 20 into second upper 
chamber 40. When in its second position, eccentric plug member 80 also 
allows for the movement of orifice plate carrier 60 through communication 
path 35, as is discussed below. 
FIG. 23 depicts a locking device to insure that a plug member is not 
inadvertently opened. Specifically, a bracket 98 is attached to a side of 
the first lower chamber 20 adjacent cover 32 by bolts 100. Bracket 98 is 
formed with at least two holes 102, 104 therein. A positioning retainer 99 
is fixed to a portion of rotational support rod 82 extending through cover 
32 and rotates therewith. Retainer 99 is formed with a hole 106 therein. 
As is shown, rotational support rod 82a can be rotated between a position 
in which hole 106 of retainer 99 is aligned with hole 104 of bracket 98 
and a second position in which hole 106 of bracket 99 is aligned with hole 
107 of bracket 99. To secure the position of plug 80, a padlock or the 
like could be passed through hole 106 when aligned with holes 102 or 104, 
thereby insuring that the plug will not be rotated inadvertently. 
Reference is now made to FIGS. 24 and 25, wherein an automatic locking 
mechanism is provided in accordance with another embodiment of the 
invention. Like numerals are utilized to indicate like structure. A 
positioning arm 94 is mounted on rotational support rod 82a to rotate 
therewith. A positioning pin 96 is slidably disposed within a hole 108 
formed therethrough. A positioning pin retainer plate 93 is mounted on 
positioning pin 96. A positioning spring 97 is disposed about pin 96 
between arm 94 and retainer plate 93. Positioning pin 96 is biased 
downward as is shown in FIG. 25 by positioning spring 97. Also provided is 
a positioning bracket 95, positioning bracket 95, like bracket 98, being 
provided with a first hole 10 and a second hole (not shown) formed 
therethrough. When positioning arm 94 is placed in the closed position and 
eccentric plug member 80 is positioned to seal the first and second 
chambers from each other, positioning pin 96 will be aligned with the 
first hole formed through positioning bracket 95. Positioning pin 96 which 
is biased downward automatically moves into first hole 110 formed in 
positioning bracket 95 by positioning spring 97, thereby ensuring that 
eccentric plug member 80 is in its proper place, and also ensuring that 
eccentric plug member 80 will not be moved inadvertently from this sealed 
position. 
When an operator wishes to open eccentric plug 80 and move it to its second 
position, whereby first lower chamber 20 and second upper chamber 40 are 
placed in fluid communication, positioning pin 96 is raised from its place 
in first hole 110 formed in positioning bracket 95 against the biasing 
force of positioning spring 97, and thereafter the positioning arm is 
moved to a position so that positioning pin 96 is aligned with the second 
hole formed in positioning bracket 95. Positioning pin 96 is again biased 
downward by positioning spring 97 and automatically moves into the second 
hole formed in positioning bracket 95, thereby locking positioning arm 94, 
and also eccentric plug member 80 into its second open position. Since 
movement of positioning arm 94 requires an operator to move positioning 
pin 96 against the biasing force of biasing spring 97, positioning arm 94 
will not be moved inadvertently. Additionally, since positioning pin 96 is 
automatically biased into the proper hole in positioning bracket 95, there 
is no possibility of an operator not employing the locking mechanism. 
In an alternative embodiment depicted in FIGS. 20 and 21, like elements 
indicated by like structure, adjustment pins 75 are designed to pass 
through slots 69 of a collar portion 68. Collar portion 68 operates 
similarly to collar portion 64 described above, except slots 69 allow 
adjustment pins to come into contact with orifice plate seal 70. In this 
embodiment, adjustment pins 75 would shift orifice plate seal 70, and thus 
in turn orifice plate 65 relative to slotted collar portion 68 and orifice 
plate carrier 60. As is shown in FIG. 21, the centering of orifice plate 
65 would be performed as above, but only orifice plate 65 and orifice 
plate seal would shift position. 
Although as described above, two adjustment pins are used, in alterative 
embodiments, as shown in FIG. 22, it is possible to provide first lower 
chamber with three adjustment pins 75 rather than the two previously 
provided. These three adjustment pins would then interface with collar 
portion 64 of orifice plate carrier 60 in three positions as is shown in 
FIG. 22. Ball plunger 77 would still be provided in order to impart a 
downward force thereon, and the positioning of orifice plate 65 would be 
achieved through the use of three pins 75. Additionally, as above, it 
would be possible to provide a slotted collar 68 with three slots 69 to 
accommodate three adjustment pins 75. These pins would contact orifice 
plate seal 70 and would operate as noted above. 
It is noted that pressure equalization valve 52 and pressure evacuation 
valve 54 are formed as separate entities. However, in an alternative 
embodiment, it is possible to utilize a single L-port valve 90 to control 
both pressure equalization and bleeding. Such an L-port valve is shown in 
FIG. 15 and is shown mounted in a second upper chamber 40' as shown in 
FIG. 26. If such a valve were utilized, the valve includes three fluid 
passages substantially forming a T as shown schematically in FIGS. 
16A-16C. A first passage 112 would extend from first lower chamber 20 to 
the valve position, a second passage 114 would extend from second upper 
chamber 40 to the valve position, and a third passage 116 would extend 
from the valve position to ambient air or of the proper evacuation area as 
is shown in FIGS. 16A-16C and FIG. 26 by way of example. Specifically, as 
shown in FIGS. 16A-16C, the trunk of the T would lead to first lower 
chamber 20, one of the two arms of the T would lead to second upper 
chamber 40 and the other of the arms of the T would lead to the proper 
evacuation point. However, any formulation of directions of the passages 
could be employed. Thus, L-port valve 90 (FIG. 15) would be displaceable 
through the use of a handle 92 or other mechanical means, between a first 
position whereby first lower chamber 20 were placed in fluid communication 
with second upper chamber 40, thereby equalizing pressure between the two 
chambers, a second position whereby second upper chamber 40 would be 
placed in fluid communication with ambient air or the proper evacuation 
means thereby forming a pressure evacuation path, and a third position 
whereby first lower chamber 20, and second upper chamber 40 would be 
sealed fluid tight from each other and from ambient air, thus constituting 
a block position. It is further noted with reference to FIGS. 15-16C, that 
the precise direction of each of the passages is specifically dependent 
upon the positioning of the valve in second upper chamber 40. The actual 
direction of any of these paths or where these paths lead may be altered 
without altering the effectiveness of this L-port valve apparatus as long 
as the three positions are performing the three required functions by 
providing the appropriate paths. 
During use, dual chamber orifice fitting 10 would be inserted in line in 
the pipeline prior to the commencement of fluid flow therethrough. 
Therefore, as noted above, inlet 21 would be connected to the pipeline 
through bolts inserted through bolt holes 23 of flange 22. Additionally, 
outlet 24 would be connected to the outlet pipeline, thereby forming a 
continuous path from the pipeline, through dual chamber orifice fitting 10 
and then back to the pipeline through outlet 24. When being assembled 
before fluid flow is commenced through the pipeline, orifice plate carrier 
60, which carries orifice plate 65 and orifice plate seal 70, is placed 
within first lower chamber 20 and in the eventual fluid flow path through 
the pipeline, this position being shown in FIG. 4 and FIG. 5. Thereafter, 
upon the commencement of fluid flow through the pipeline, orifice plate 65 
will already be in place, and the measurement of fluid can begin. Note 
that it might be necessary, after fluid flow begins, if orifice plate 65, 
or orifice plate carrier 60 were to shift its position, to utilize 
adjustment pins 75 in order to center orifice plate 65 within the pipeline 
as described above, and as will be further described below. 
After fluid flow through the pipeline has been started, operations might be 
necessary while the fluid flow continues. These consist of removing the 
orifice plate in order to change the orifice plate, perform any other 
maintenance, or for any other reason. 
To remove orifice plate 60, it is first necessary to move eccentric plug 
member 80 from its first position, in which it forms a fluid tight seal 
between first chamber 20 and second chamber 40 to its second position 
whereby first lower chamber 20 and second upper chamber 40 are placed in 
fluid communication with each other. However, before eccentric plug member 
80 is moved, it is necessary to open pressure equalization valve 52 to 
place the two chambers 20 and 40 in fluid communication, thereby allowing 
second upper chamber 40 to fill with fluid and reach a pressure equal to 
that in first lower chamber 20. After the pressure between the two 
chambers is equalized, equalization valve 52 is closed. Thereafter, the 
movement of eccentric plug member 80 is achieved through the rotation of 
positioning arm 94 by removing positioning pin 96 from the first hole in 
positioning bracket 95, rotating the positioning arm 90.degree., or any 
other required rotational amount based on gearing mechanisms, and 
releasing positioning pin into the second through hole in positioning 
bracket 95. It should be noted that this procedure could also be performed 
without the positioning bracket, by simply moving the positioning arm 94 
from a first position to a second position. Movement of plug 80 may be 
accomplished without positioning arm 94 by directly turning rotating 
rotational support rod 82a. Movement of positioning arm 94 in turn rotates 
rotational support rod 82 to which eccentric plug member 80 is fixed. 
As is further shown in FIG. 4, outer circumferential face 81 of eccentric 
plug member 80 is moved away from radially engaging face 86 of plug 
fitting 85, thereby opening communication path 35 between first lower 
chamber 20 and second lower chamber 40, placing these chambers in fluid 
communication with each other. It should be noted that if the apparatus is 
operated with communication path 35 open, it is not necessary to perform 
these first two steps, since the chambers will be in fluid communication 
through communication path 35, and thus at equal pressure. Also eccentric 
plug member 80 will already be in its second position. 
Movement of eccentric plug member 80 from its first position to its second 
position further opens up communication path 35 to allow orifice plate 
carrier 60 and its associated components to pass therethrough. After 
communication path 35 has been opened, the next step required is to move 
orifice plate carrier 60 vertically out of the fluid flow path in the 
pipeline. Because eccentric plug 80 is eccentric and substantially 
C-shaped, it is positioned out of the travel path of orifice carrier plate 
60. By rotating rotational movement rod 62 in a predetermined direction, 
gears 63, meshing with racks 66 and 67 moves orifice plate carrier 60 
towards communication path 35. Gear 63 mounted on rotational movement rod 
62 remain meshed with parallel gear racks 66 and 67 mounted on orifice 
plate carrier 60. When rotational movement rod 62 is rotated in the proper 
direction, gears 63 move orifice plate carrier 60 upward through contact 
with parallel gear racks 66 and 67. This rotation is continued until the 
lower edge of orifice plate carrier 60 reaches the level of rotational 
movement rods 62. 
At this point, orifice plate carrier 60 will be contained within 
communication path 35, and will be situated between first lower chamber 20 
and second upper chamber 40. Additionally at this time, gears 45 mounted 
on plate movement rod 44 will have come into contact with parallel gear 
racks 66 and 67 mounted on orifice plate carrier 60. Rotation of plate 
movement rod 44 moves orifice plate carrier 60 further in the vertical 
position when gears 45 mesh with parallel gear racks 66 and 67. To 
continue the movement of orifice plate carrier 60 into cavity 56, plate 
movement rod 44 is rotated in the predetermined direction, and gears 45 
move orifice plate carrier 60 into cavity 56 by meshing parallel gear 
racks 66 and 67. This movement is continued until the entirety of orifice 
plate carrier 60 is contained within second upper chamber 40. 
At this time, it is necessary to seal second upper chamber 40 from first 
lower chamber 20 before opening second upper chamber 40 and removing 
orifice plate carrier 60. This is achieved by the movement of eccentric 
plug member 80 from its second position, whereby communication path 35 is 
open and first lower chamber 20 and second upper chamber 40 are in fluid 
communication with each other, to its first position, whereby first lower 
chamber 20 and second upper chamber 40 are sealed from each other. This 
movement is achieved by the opposite step required to move eccentric plug 
member 80 from its first position to its second position, specifically 
moving positioning pin from the second through hole in positioning bracket 
95, rotating positioning arm in the direction opposite to that utilized 
previously, and replacing positioning pin 96 in the first hole of 
positioning bracket 95. This movement rotates rotational support rod 82a 
in the proper direction, thereby replacing outer circumferential face 81 
of eccentric plug member 80 against radial engaging face 86 of plug 
fitting 85. It should be noted at this time that no additional grease or 
sealant material is required to be inserted into the mechanism in order to 
insure a proper seal. Because of the use of eccentric plug member 80, and 
the specific shape thereof, the engagement between outer circumferential 
face 81 and radially engaging phase 86 is fluid tight, and is aided by the 
pressure of the fluid in first lower chamber 20 against inner face 83 of 
eccentric plug member 80. 
After eccentric plug member 80 has been replaced, first lower chamber 20 
and second upper chamber 40 will be sealed from each other, thereby 
sealing second upper chamber 40 from the fluid flow through the pipeline. 
However, at this time, the pressure of the fluid within second upper 
chamber 40 is greater than atmospheric pressure, and would be somewhat 
similar to the pressure imparted by the fluid flow through the pipeline. 
Therefore, it is necessary to release the pressure in this second upper 
chamber 40 before opening second upper chamber 40. Therefore, pressure 
evacuation valve 54 is opened to allow the fluid to be evacuated from 
second upper chamber 40 through pressure evacuation path 55. It is noted 
that this pressure evacuation path through pressure evacuation valve 54 
may evacuate the fluid within second upper chamber 40 to ambient air, or 
to other proper waste facility, depending upon the type of fluid being 
transported in the pipeline. After opening pressure evacuation valve, the 
pressure within second upper chamber 40 will drop to ambient pressure, and 
thereafter pressure evacuation valve 54 can be closed. 
At this point in time, it is then possible to open second upper chamber 40, 
since the chamber is no longer pressurized, and thereafter remove orifice 
plate carrier 60. This opening is achieved as is shown in FIG. 3 and FIG. 
4, by the removal of retaining bolts 47 from upper retaining member 46 and 
retaining fitting 46a. After these bolts are removed, both upper retaining 
member 46 and retaining fitting 46a may be removed from the upper portion 
of second upper chamber 40. Thereafter, to allow for the removal of 
orifice plate carrier 60, it is necessary to further rotate plate movement 
rod 44 in the proper direction to urge orifice plate carrier 60 further in 
the vertical direction, and therefore out of the upper portion of second 
upper chamber 40. After orifice plate carrier 60 is removed from second 
upper chamber 40, it is possible to remove orifice plate 65 and orifice 
plate seal 70, in order to insert a new orifice plate seal 70 and orifice 
plate 65, or to perform any repairs required on any of the parts. 
Therefore, by removing the orifice plate using the dual chamber orifice 
fitting 10, it is possible to remove such plate without the requirement of 
interrupting the flow of fluid through the pipeline. 
Next, after repairs or replacement has been performed, orifice plate 65 and 
orifice plate seal 70 would be replaced in orifice plate carrier 60, to 
form a unit as described above. Thereafter, it is necessary to reinsert 
orifice plate carrier 60 into the path of the fluid flow through the 
pipeline. Therefore, orifice plate carrier 60, containing orifice plate 65 
and orifice plate seal 70 is inserted into the upper portion of second 
upper chamber 40 until parallel gear racks 66 and 67 come into contact 
with gears 45 of plate movement rod 44. Thereafter, plate movement rod 44 
is rotated in the proper direction, opposite the above described 
predetermined direction, to move orifice plate carrier downward into 
second upper chamber 40. This direction will be opposite of that 
previously used to move orifice plate carrier upward. Movement will be 
achieved through gears 45 engaging parallel gear racks 66 and 67 and 
urging orifice plate carrier 60 downward in the vertical direction. This 
movement is continued until the entire orifice plate carrier 60 is 
contained within second upper chamber 40. Thereafter, upper retaining 
member 46 and retaining fitting 46a are placed in their proper positions 
within second upper chamber 40, and retaining bolts 47 are inserted and 
tightened to secure upper retaining member 46 and retaining fitting 46a 
within second upper chamber 40, thereby forming a fluid tight seal, and 
sealing second upper chamber 40 from ambient air or the like. 
Next, it is necessary to close pressure evacuation valve 54 and then to 
equalize the pressure between second upper chamber 40 and first lower 
chamber 20 before communication path 35 is opened. Therefore, pressure 
equalization valve 52 should be opened, therefore placing first lower 
chamber 20 and second upper chamber 40 in fluid communication with each 
other through pressure equalization path 35. The opening of this pressure 
equalization path allows fluid from first lower chamber 20 to enter second 
upper chamber 40, thereby equalizing the pressure therebetween. 
It should be noted that if the L-port valve of FIG. 15 is utilized, the 
steps described regarding pressure evacuation valve 54 and pressure 
equalization valve 52 would be performed somewhat differently. 
Specifically, when the two chambers are to be sealed from each other, the 
L-port valve would be placed in a block position, as shown in FIG. 16C. 
During the pressure evacuation step, the L port would be placed in an 
evacuation position as is shown in FIG. 16B. This would allow second upper 
chamber 40 to be in fluid communication with ambient air, or other 
evacuation mechanisms. Finally, when the equalization step is performed 
between first lower chamber 20 and second upper chamber 40, the L-port 
valve would be placed in an equalizing position as shown in FIG. 16A, 
thereby placing first lower chamber 20 in fluid communication with second 
upper chamber 40. As noted above, the use of this L-port valve allows for 
ease of choice between the three positions, and also insures that both the 
pressure equalization valve and pressure evacuation valve are not opened 
at the same time, thereby reducing the danger involved in removing orifice 
plate carrier 60 from the fluid flow of the pipeline. 
After the pressure has been equalized between the two chambers, eccentric 
plug member 80 is opened, thereby opening communication path 35 between 
first lower chamber 20 and second upper chamber 40. Eccentric plug member 
80 is opened through the same procedure as is followed above to move 
eccentric plug member 80 from its first position to its second position. 
After communication path 35 is opened, plate movement rod 44 is further 
rotated in the direction whereby orifice plate carrier 60 is moved into 
first lower chamber 20. This movement is continued until parallel gear 
racks 66 and 67 no longer mesh with gears 45 of plate movement rod 44. 
After orifice plate carrier 60 moves into communication path 35, gears 63 
will mesh with the lower edge of orifice plate carrier 60 and parallel 
gear racks 66 and 67. Thereafter, rotational movement rod 62 is moved in 
the proper direction so as to continue and complete the movement of 
orifice plate carrier 60 into first lower chamber 20, and into the path of 
fluid flow in the pipeline. 
After the downward movement of orifice plate carrier 60 by rotational 
movement rod 62 has been completed, orifice plate carrier 60 will be 
properly positioned within the fluid flow in the pipeline. Thereafter, 
eccentric plug member 80 is closed so as to seal first lower chamber 20 
and second upper chamber 40 from each other. The movement of this 
eccentric plug member 80 from its second position to its first position is 
performed as is noted above when removing orifice plate carrier 60. 
Additionally, the pressure in second upper chamber should be released 
through the use of pressure evacuation valve 54 as described above. If 
dual chamber orifice fitting 10 is to be operated with eccentric plug 
member 80 in the open, or second position, the last two steps of moving 
eccentric plug member 80 and releasing the pressure in second upper 
chamber 40 need not be performed. 
After orifice plate carrier 60 has been replaced in the fluid flow path of 
the fluid in the pipeline, if necessary, adjustment pins 75 may be 
employed to insure that the orifice plate and hole therethrough is 
centered within the pipeline. As noted above during the description of 
these adjustment pins, either two adjustment pins or three adjustment pins 
may be provided. These adjustment pins may be adjusted from outside of 
dual chamber orifice fitting 10, and may be used to insure that the 
orifice plate is properly centered in the fluid flow path while the fluid 
continues to flow. After the orifice plate has been properly centered, 
measurement of the fluid flow in the pipeline can be resumed. 
Thus, an improved dual chamber orifice fitting has been disclosed, wherein 
an improved plug member is utilized, adjustment pins may be used to insure 
proper centering of the orifice plate, a single valve may be used for 
pressure equalization and pressure evacuation, and an improved seal member 
is provided on the orifice plates to insure proper measurement. Each of 
these improvements is beneficial to the overall functioning of the dual 
chamber orifice plate, and insures more accurate measurement of fluid flow 
in a pipeline measured thereby. 
Because of its shape, the pressure of the fluid against the eccentric plug 
aids to maintain the fluid tight seal between the first and second 
chambers, and no additional grease or sealing fluid is required to 
maintain a fluid tight seal. Additionally, since the eccentric plug moves 
rotationally, as opposed to the lateral movement which is employed in the 
prior art, it is possible to easily move the plug to and from the first 
and second positions and the rotation may be geared in any way to provide 
any additional mechanical advantage necessary to overcome the fluid 
pressure against the eccentric plug. 
An orifice plate seal is provided which specifically maintains its seal, 
and is in fact aided by the pressure of the fluid flowing in the pipeline. 
During upward or downward movement of the orifice plate when it is being 
inserted into or removed from the pipeline, a fluid tight seal is 
maintained around the outer edge of the seal, and therefore all fluid 
flowing through the pipeline is directed through the through hole formed 
in the orifice plate. 
It will thus be seen that the objects set forth above, and those made 
apparent from the preceding description, are efficiently attained and, 
since certain changes may be made in the above construction without 
departing from the spirit and scope of the invention, it is intended that 
all matter contained in the above description or shown in the accompanying 
drawings shall be interpreted as illustrative and not in a limiting sense. 
It is also to be understood that the following claims are intended to cover 
all of the generic and specific features of the invention herein 
described, and all statements of the scope of the invention which, as a 
matter of language, might be said to fall therebetween.