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September 2004
Flowcell Location
Transducer Location
1-2
A flowcell is the section of pipe where the transducers are mounted. It
can be created either by mounting the transducers on the existing
pipeline or by mounting them on a spoolpiece. A spoolpiece is a
separately manufactured pipe section, matched to the existing pipe,
which contains ports for mounting the transducers. A spoolpiece
allows the transducers to be aligned and calibrated before inserting
the flowcell into the pipeline.
Ideally, install the flowcell in a section of pipe with unlimited access,
such as a long section of pipe that is above ground. However, if the
flowcell must be installed in an underground pipe, dig a pit around the
pipe to facilitate installation.
For a given fluid and pipe, the accuracy of the AT868 depends
primarily on the location and alignment of the transducers. In addition
to accessibility, when planning for transducer location, follow these
guidelines:
•
Locate the transducers so that there are at least 10 pipe diameters
of straight, undisturbed flow upstream and 5 pipe diameters of
straight, undisturbed flow downstream from the measurement
point. Undisturbed flow means avoiding sources of turbulence in
the fluid such as valves, flanges, expansions, and elbows; avoiding
swirl; and avoiding cavitation.
•
Locate the transducers on a common axial plane along the pipe.
Install the transducers on the side of the pipe instead of the top or
bottom, because the top of the pipe accumulates gases and the
bottom of the pipe accumulates sediment. These conditions cause
attenuation of the ultrasonic signal. There is no similar restriction
with vertical pipes. However, vertical pipes with downward flow
should be avoided to ensure a full pipe at the measurement point.
Installation
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