Chapter 4. Error Codes and Troubleshooting
76 AT600 User’s Manual
4.2.2a Fluid Problems (cont)
4. The fluid sound speed must not vary excessively.
The AT600 will tolerate relatively large changes in the fluid sound speed, as may be caused by variations in fluid
composition and/or temperature. However, such changes must occur slowly. Rapid fluctuations in the fluid sound
speed, to a value that is considerably different from that programmed into the AT600, will result in erratic or
inaccurate flow rate readings. Refer to Chapter 3, Initial Setup and Programming, and make sure that the
appropriate sound speed is programmed into the meter.
4.2.2b Pipe Problems
Pipe-related problems may result either from a failure to observe the installation instructions, as described in Chapter 2,
or from improper programming of the meter. 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 location(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, and in some cases, transducers that protrude into the flow stream may be used. Refer to Chapter 2,
Installation, for more details on proper installation practices.
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, 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 3, Initial Setup, for instructions on programming the pipe data.
In addition to the actual pipe dimensions, the path length (P) and the axial dimension (L), based on the actual
transducer mounting locations, must be accurately programmed into the flowmeter. For a GE Sensing flowcell, this
data will be included with the documentation for the system. If the transducers are mounted onto an existing pipe,
these dimensions must be precisely measured.
3. The inside of the pipe or flowcell must be relatively clean.
Excessive buildup of scale, rust or debris will interfere with flow measurement. Generally, a thin coating or a solid
well-adhered build up on the pipe wall will not cause problems. Loose scale and thick coatings (such as tar or oil)
will interfere with ultrasound transmission and may result in incorrect or unreliable measurements.
4.2.3 Transducer Problems
Ultrasonic transducers are rugged, reliable devices. However, they are subject to physical damage from mishandling
and chemical attack. The following list of potential problems is grouped according to transducer type. Contact GE if
you cannot solve a transducer-related problem.
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