GE PanaFlow XMT1000, User Manual

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PanaFlow™ XMT1000 User’s Manual 27
Chapter 3. Error Codes and Troubleshooting
3.2 Diagnostics
3.2.1 Introduction
This section explains how to troubleshoot the XMT1000 if problems arise with the electronics enclosure, the flowcell,
or the transducers. Indications of a possible problem include:
•
Display of an error message on the LCD display screen, Vitality PC software, or HART.
•
Erratic flow readings
•
Readings of doubtful accuracy (i.e., readings which are not consistent with readings from another flow
measuring device connected to the same process).
If any of the above conditions occurs, proceed with the instructions presented in this section.
3.2.2 Flowcell Problems
If preliminary troubleshooting with the Error Code Messages and/or the Diagnostic Parameters indicates a possible
flowcell problem, proceed with this section. Usually, flowcell problems are either fluid problems or pipe problems .
Read the following sections carefully to determine if the problem is indeed related to the flowcell. If the instructions in
this section fail to resolve the problem, contact GE for assistance.
3.2.2a Fluid Problems
Most fluid-related problems result from a failure to observe the flow meter system installation instructions. Refer to
Chapter 1, Installation, to correct any installation problems.
If the physical installation of the system meets the recommended specifications, it is possible that the fluid itself may
be preventing accurate flow rate measurements. The fluid being measured must meet the following requirements:
•
The fluid must be homogeneous, single-phase, relatively clean and flowing steadily.
Although a low
level of entrained particles may have little effect on the operation of the XMT1000, excessive amounts of solid
or gas particles will absorb or disperse the ultrasound signals. This interference with the ultrasound
transmissions through the fluid will cause inaccurate flow rate measurements. In addition, temperature
gradients in the fluid flow may result in erratic or inaccurate flow rate readings.
•
The fluid must not cavitate near the flowcell.
Fluids with a high vapor pressure may cavitate near or in the
flowcell. This causes problems resulting from gas bubbles in the fluid. Cavitation can usually be controlled
through proper installation design.
•
The fluid must not excessively attenuate ultrasound signals.
Some fluids, particularly those that are very
viscous, readily absorb ultrasound energy. In such a case, an error code message will appear on the display
screen to indicate that the ultrasonic signal strength is insufficient for reliable measurements.
•
The fluid sound speed must not vary excessively.
The XMT1000 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 above
the limit programmed into the XMT1000, will result in erratic or inaccurate flow rate readings. Refer to
Chapter 2, Programming, and make sure that the appropriate sound speed limit is programmed into the meter.