SITRANS F Ultrasonic flowmeters FST030 (HART)
Operating Instructions, 08/2017, A5E35971532-AC
85
Diagnosing and troubleshooting
9
This chapter describes various deviations from normal operation and lists suggested remedy
actions.
For more information on alarms/warnings shown in the display, see Fault codes and
corrective actions (Page 90).
9.1
Unexpected behavior
Only two general groups of errors are shown in the display: Process errors and Device
errors.
Device errors describe hardware errors, see Fault codes and corrective actions (Page 90).
Two main groups of process errors are:
●
Measuring path error
The medium in the measuring line is not permeable to sound; this applies when the liquid
is highly aerated, has high solids content, or is an emulsion, or when the pipe is empty.
The measured value on the display is set to zero. Cable is broken or detached.
The measured values have a very high dispersion so that errors in the measuring signal
evaluation is indicated. It can be caused by disturbances in the flow pipe due to
cavitation, twist or inhomogeneity such as bubbles or foreign bodies.
●
Flow measurement unreliable
The measured value on the display is set to zero and "Maintenance alarm" appears and
the bottom of the screen.
Table 9- 1
Error symptoms
Symptoms
Diagnostics
Cause
Remedy
Display shows no flow
•
Error "Measurement path
error" is pending
•
Gain for the active paths >
250
•
Transit time for the active
paths is not stable
•
Error counters are not equal
to 0.
Pipe not filled with liquid Make sure that the pipe is filled or at
least the sound path is covered with
liquid.
Cable broken/detached Make sure that the sensor cable is
connected in the terminal housing of
the transmitter.
Make sure that the screen and cen-
ter pin is connected inside the sen-
sor top.
Permanent disturbance
inside the pipe
If possible, make sure that the sen-
sor window inside the pipe is not
damaged or that no permanent
disturbance is present.