GE CTF878, User & Service Manual

Page: 48 / 72

February 2009
4-4 Troubleshooting
Pipe/Fluid Problems
If preliminary troubleshooting with the Error Code Messages and/or
the Diagnostic Menu indicates a possible pipe/fluid problem, proceed
with this section. Pipe/fluid problems fall into two categories:
•
gas problems
•
pipe problems.
Read the following sections carefully to determine if the problem is
indeed related to the pipe/fluid. If the instructions in this section fail
to resolve the problem, contact the factory for assistance.
Gas Problems
Most gas-related problems result from a failure to observe the
flowmeter system installation instructions. Refer to
Installation ,
Chapter 2 of the Startup Guide, 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:
1.
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 CTF878, excessive amounts of solid or
liquid particles will absorb or disperse the ultrasound signals. This
interference with the ultrasound transmissions through the gas will
cause inaccurate flow rate measurements.
2.
The gas must not excessively attenuate ultrasound signals.
Some gases (i.e., high-purity carbon dioxide, hydrogen, etc.)
readily absorb ultrasound energy. In such a case, an
E4
and/or
E6
error code message will appear on the display screen to indicate
that the ultrasonic signal strength is insufficient for reliable
measurements.