PanaFlow™ XMT1000 User’s Manual 69
Chapter 4. Error Codes and Troubleshooting
4.4 Fluid and Pipe Problems
If preliminary troubleshooting with the Error Code Messages and the Diagnostic Parameters indicates a possible
problem, proceed with this section. Measurement problems fall into two categories:
• Fluid problems
• Pipe problems
Read the following sections carefully to determine if the problem is related to the fluid or the pipe. If the instructions in
this section fail to resolve the problem, contact Panametrics for assistance.
4.4.1 Fluid Problems
Most fluid-related problems result from a failure to observe the flow meter system installation instructions, as
described in Chapter: Installation.
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 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 measurement point.
Fluids with a vapor pressure relatively close to process pressure may cavitate near the measurement point.
Cavitation can usually be controlled through proper system 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, signal
warning and error message will appear on the display screen to indicate that the ultrasonic signal strength is
insufficient for reliable measurements.
• The fluid soundspeed 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. Also, fluctuations in fluid
sound speed due to changes in temperature will likely recover independently. Rapid fluctuations in the fluid
sound speed, to a value that is beyond ± 20% from that programmed into the XMT1000, will result in erratic or
inaccurate flow rate readings. This may occur when changing batch fluids.
Note:
Refer to Chapter 3: Programming, to make sure the appropriate soundspeed is programmed into the meter.
4.4.2 Pipe Problems
Pipe-related problems may result from improper choice in meter location or errors in programming. The following
may result in problematic installations:
• The collection of material at the transducer location(s).
Accumulated debris at the transducer locations will interfere with the transmission of the ultrasound signals. As a
result, accurate flow rate measurements are not possible. Realignment of the transducers often corrects these
problems but, in some cases, wetted transducers must be used. Refer to Chapter: Installation for more details on
proper installation practices.
• Inaccurate pipe measurements.
The flow rate measurement accuracy relies greatly on the accuracy of the programmed pipe dimensions.
Measure the pipe wall thickness and diameter with the same accuracy desired in the flow rate readings. Also,
check the pipe for dents, pitting or rough surfaces, eccentricity, weld deformity, straightness and other factors
that may cause inaccurate readings. Refer to the Chapter: Programming, for instructions on entering the pipe
data.
• The inside of the pipe or pipe is not sufficiently clean.
Excessive buildup of scale, rust or debris inside the pipe will interfere with flow measurements. 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 flow rate
measurements.
To Next Page
Loading...