GE PT878GC Manual De Usuario

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April 2004
10-10
Diagnosis and Troubleshooting
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 dimensions. For a flowcell supplied by 
GE Panametrics, the correct data will be included in the 
documentation. For other flowcells, 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.