Baker Hughes Panametrics Sentinel LCT8, Руководство пользователя

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5.5 Transducer problems
The Sentinel LCT8 transducers are rugged, reliable devices
that do not come into contact with the process fluid. If
erratic or inaccurate readings can be tracked to a problem
with one or more transducers, such as physical damage,
the Panametrics field service team has the appropriate
methods and tools to properly replace the transducer to
maintain the accuracy of your flow meter system without
the need to recalibrate the system. Contact your local
Panametrics representative to schedule this service.
5.6 Uncertainty in flow rate for a
non-insulated flowcell
Dimensional compensation considers the effect on the
geometrical dimensions of the flowcell due to the material
thermal expansion or contraction. The fluid temperature
inside the flowcell is measured and used for this purpose.
Under severe ambient conditions, such as -40°C in winter,
the fluid temperature can be very different, by up to 10°C,
from the pipe wall temperature. This will cause about a
0.04% error in the measured flow rate. Figure 93 below
indicates that the errors increase as the difference between
the fluid and the ambient temperatures for both insulated
and non-insulated flowcells. For non-insulated flowcells,
at large temperature differences, the error is about one
order of magnitude higher than that for insulated flowcells.
Therefore, for applications in severe weather conditions, it is
recommended that the flowcell be insulated to ensure the
accuracy of the meter.
Meter with insulation
Meter without insulation
-40 -20 0 20 40 60 80 100 120
-0.02
-0.01
0
0.01
0.02
0.03
0.04
0.05
Temperature difference between fluid and ambient (deg c)
Error in flow rate (%)
Figure 93: Example of flow error at Various temperature differences
97