Diagnostics; Introduction; Flowcell Problems - GE PanaFlow HT User Manual

Chapter 4. Error Codes and Troubleshooting

4.3 Diagnostics

4.3.1 Introduction

This section explains how to troubleshoot the PanaFlow HT 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 that 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 chapter.

4.3.2 Flowcell Problems

If preliminary troubleshooting with the Error Code Messages and/or the Diagnostic Parameters indicates a possible
flowcell problem, proceed with this section. Flowcell problems fall into two categories: 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.
4.3.2a Fluid Problems
Most fluid-related problems result from a failure to observe the flowmeter system installation instructions. Refer to
Chapter 2, 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:
1. 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 PanaFlow HT, 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.
2. 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.
3. 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.
4. The fluid sound speed must not vary excessively.
The PanaFlow HT 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 PanaFlow HT, will result in
erratic or inaccurate flow rate readings. Refer to Chapter 3, Initial Setup and make sure that the appropriate sound
speed is programmed into the meter.
80 PanaFlow HT User's Manual