Measuring and testing – Probe or probe mounting
Reexamination Certificate
2001-08-30
2004-07-13
Garber, Charles D. (Department: 2856)
Measuring and testing
Probe or probe mounting
Reexamination Certificate
active
06761078
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to meters that measure the flow of a fluid. More particularly, the present invention relates to ultrasonic meters measuring fluid flow through a pipe. Still more particularly, the present invention relates to a structure for mounting transducers to an ultrasonic flow meter.
2. Description of the Related Art
After a hydrocarbon, such as natural gas, has been removed from the ground, it is often transported from place to place via pipelines. Very often, an owner or operator of a pipeline desires to accurately know how much gas is flowing through the pipeline. For example, where a billion standard cubic feet of natural gas flows through a single pipeline, even small percentage errors can result in serious miscalculations regarding the amount of gas flowing through the pipeline. Further, particular accuracy for the measurement is demanded when gas is changing hands, or “custody”, because custody transfer applications often involve the exchange of money. Even so, an accurate meter is desirable for all phases of gas or fluid production, transportation, and distribution operations, and for off-shore platforms.
In response to the need for accurate gas flow measurement, ultrasonic flowmeters were developed. Ultrasonic flowmeters, also named sonic or acoustic flowmeters, revolutionized the gas industry because of their many advantages. For example, ultrasonic flowmeters are accurate over a large range of flow rates. Because ultrasonic gas flowmeters are non-intrusive, gas flows through the gas pipeline without encountering an increased pressure region. Consequently, considerable savings are achieved because the gas flows more easily in the pipe. In addition, ultrasonic flowmeters can also measure gas flow accurately despite changing gas composition.
FIG. 1
shows a prior art ultrasonic transducer mount
100
. The mount
100
includes a base
130
with a side surface
131
and a flat surface
132
. Arcuately located on the base flat surface
132
are cap screw holes
110
-
113
for receiving cap screws
114
-
117
(not shown) respectively. Also located on base flat surface
132
are two jackscrew holes
120
,
121
located 180° apart for receiving jackscrews (not shown). The jackscrews are used for removal of the mount from the meter housing. Also located on the base flat surface
132
are two mount cover holes
118
,
119
located 180° apart for receiving the mount cover screws (not shown). Extending from the base
130
is a holder sleeve
140
. The inner diameter (ID) of the holder sleeve
140
engages a transducer holder that holds a transducer (not shown). On the outside of holder sleeve
140
is union sleeve
150
. Sleeve
150
is not removable from holder sleeve
140
. On the outer diameter (OD) of union sleeve
150
are threads
151
for engagement with a union nut (not shown). The union nut is part of an extractor tool (not shown) for removal of the transducer holder and transducer.
In operation, the cap screws (not shown) attach the mount
100
to a meter housing (not shown). The transducer and transducer holder are then inserted into the holder sleeve
140
. Once inserted, the transducer holder forms a fluid-tight seal at the joint with the holder sleeve. A mount cover (not shown) attaches to the mount base with screws that engage the mount cover holes
118
,
119
. The mount cover locks the transducer holder in place and prevents inadvertent disassembly during use and electrical connection to the transducer.
For removal of the transducer holder and transducer, first the mount cover is removed. The extractor tool (not shown) is then attached to the transducer mount. The extractor tool consists of an extractor tool valve (not shown) and a removable unit for isolation of the transducer holder and transducer from the transducer mount and meter housing. The extractor tool attaches to the transducer mount by the extractor tool valve union nut (not shown) engaging the union sleeve threads
151
. Once engaged, the extractor tool makes an fluid-tight seal with the union valve seal. This seal allows removal of the transducer holder and transducer without releasing pressure from the meter housing and pipeline. The transducer and transducer holder are then removed from the holder sleeve
140
through the extractor tool valve and placed in a chamber in the extractor tool removable unit. Once the transducer holder and transducer are removed, the chamber is sealed from the holder sleeve. Once sealed, the transducer and transducer holder can be removed from the extractor tool.
For removal of the transducer mount
100
, pressure must be vented from the housing and the cap screws (not shown) must be removed. Jackscrews are then inserted into jackscrew holes
120
,
121
. As the screws draw into the holes, they engage the meter housing surface. Further drawing the screws into the jackscrew holes forces the mount
100
out of engagement with the meter housing.
The large size of the current T-slot transducer mount provides certain drawbacks. Specifically, the current transducer mount causes problems with small meter housings. For example, the cast bosses for the very large OD transducer mounts greatly increase the casting weight of the housing casting because of the material needed at each transducer location boss to allow the mount to be attached. The housing transducer location bosses for the very large OD mounts also greatly increase the end to end length of the meter housing. The increased length is a major concern because the bore of the meter must be machined. The ability to machine a small ID over a very long length becomes harder as the length increases. This is true even if the bore is machined from each end. There are also cost issues concerned with the large size transducer mounts because of the large amount of material used.
It would be advantageous to design a transducer mount that is smaller in size than conventional designs, and that can be manufactured more inexpensively. Ideally, the new transducer mount would be compatible with existing extractor tools, transducers, and holders to facilitate a smooth transition to the new mount design. The new transducer mount would also allow for a smaller size meter housing than conventional meter housings. The smaller size meter housing would have a decreased casting weight and a decreased end to end length. It would also be advantageous to locate the transducer ports in the housing in the same location for different pressure rating transducer mounts. Despite the apparent advantages of such a transducer mount, to date no such mount has been commercially introduced.
SUMMARY OF THE INVENTION
The present invention comprises an improved ultrasonic transducer mount. Unlike prior transducer mounts, the improved transducer mount includes a removable union sleeve with an outer diameter (OD) that engages the inner diameter (ID) of the extractor tool union nut. A retaining ring holds the union sleeve in place on the outside of a transducer holder sleeve. The union sleeve and the retaining ring need only be used with the extractor tool for removal of the transducer.
According to an exemplary embodiment, the union sleeve fits over a holder sleeve on the mount. The holder sleeve has at least one flat surface that engages a similar configuration on the ID of the union sleeve. The flat surface(s) prevent(s) relative rotation between the union sleeve and holder sleeve after installation on the mount and during engagement and disengagement of the extractor tool.
The end of the union sleeve contacting the retaining ring includes a counter bore on the contacting face. The counter bore fully circumscribes the retaining ring when the union nut pulls the union sleeve against the retaining ring during engagement. This counter bore prevents inadvertent disassembly of the retaining ring from the groove if the extractor tool valve rotates as
Conley & Rose, P.C.
Daniel Industries Inc.
Garber Charles D.
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