April 2004
10-10 Diagnosis and Troubleshootin g
Fluid Problems (cont.)
3. THE GAS SOUND SPEED MUST NOT VARY
EXCESSIVELY. The TransPort will tolerate relatively large,
changes in gas sound speed due to changes in gas composition
and temperature. However, such changes must occur slowly.
Rapid fluctuations in the gas sound speed, to a value that is
considerably different from that programmed into the
PT878GC, will result in erratic or inaccurate flow rate
readings. Refer to Chapter 4, Programming Site Data, pages
4-13 and 4-14.
Pipe Problems
Improper pipe conditions and/or flowcell installation can cause
problems with measurement of the gas flow. Contact GE
Panametrics if you cannot solve pipe-related problems. By far,
the most common pipe problems are the following
1. THE COLLECTION OF MATERIAL AT THE
TRANSDUCER LOCATION(S). Accumulated debris at the
transducer locations(s) will interfere with transmission of the
ultrasound signals. As a result, accurate flow rate
measurements are not possible. Realignment of the flowcell or
transducers often cures such problems. Refer to Chapter 3 for
proper transducer installation.
2. INACCURATE PIPE MEASUREMENTS. The accuracy of
the flow rate measurements is no better than the accuracy of
the programmed pipe dimen sions. For a flowcell supplied by
GE Panametrics, the correct data will be included in the
documentation. For other flow cells, measure the pipe wall
thickness and diameter with the same accuracy desired in the
flow rate readings. Also, check the pipe for dents, eccentricity ,
weld deformity, straightness and other factors that may cause
inaccurate readings. Refer to Chapter 4, Programming Site
Data, pages 4-7 to 4-10, for instructions on programming the
pipe data.