Flowcell Problems; Gas Problems - Panametrics Sentinel User Manual

Chapter 5. Diagnostics
5.4

Flowcell Problems

If preliminary troubleshooting using the Error Codes in Chapter 4 and "Displaying Diagnostic Parameters" on
page xcv indicates a possible flowcell problem, proceed with this section.
Flowcell problems fall into two general categories:

• Gas problems

• 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 Panametrics for assistance.
5.4.1 Gas Problems
Most gas-related problems result from a failure to observe the Sentinel Flow Measurement 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 gas itself may
be preventing accurate flow rate measurements. The gas being measured must meet the following requirements:
• The gas must be homogeneous, single-phase and relatively clean.
Although a low level of entrained particles may have little effect on the operation of the Sentinel system,
excessive amounts of solid (smoke) or liquid (steam) particles will absorb or disperse the ultrasound signals.
This interference with the ultrasound transmissions through the gas will cause inaccurate flow rate
measurements. In addition, temperature gradients in the gas flow may result in erratic or inaccurate flow rate
readings.
• The gas must not excessively attenuate ultrasound signals.
Some gases (e.g., high-purity carbon dioxide, hydrogen, nitrogen, etc.) readily absorb ultrasound energy. In
such cases, an E1 error code message will appear on the meter display screen to indicate that the ultrasonic
signal strength is insufficient for reliable measurements.
• The gas soundspeed must not vary excessively.
The Sentinel system will tolerate relatively large changes in the gas soundspeed, as may be caused by
variations in gas composition or temperature. However, such changes must occur slowly. Rapid fluctuations in
the gas soundspeed, to a value that is considerably different from that programmed into the Sentinel, will result
in erratic or inaccurate flow rate readings. Refer to "Displaying Measurements" on page lxxix, and make sure
that the appropriate soundspeed appears in the soundspeed display.
98 Sentinel™ User's Manual