Siemens SITRANS FC410 Operating Instructions Manual page 88

Troubleshooting/FAQs
10.2 Troubleshooting
Step 1: Inspecting the application
Ensure that:
1. The sensor is installed as described in Installing/mounting (Page 27).
2. The sensor is located in a vibration-free position. Vibrations can disturb the sensor and
therefore cause measurement error.
Depending on application, you should furthermore ensure the following:
● Liquid application
Ensure that the sensor is filled with liquid and liquid only.
Air or gas bubbles in the liquid cause instability and can result in measurement errors.
Flush the pipe systems and the sensor for several minutes at maximum flowrate to
remove any air bubbles which may be present.
Note
The liquid must be homogeneous in order to measure with high accuracy. If the liquid
contains solid particles of greater density than the liquid, then these solids can settle,
especially at low flow rates, which will cause instability in the sensor and lead to
measurement errors.
For pastes or process fluids with suspended solids always orient the sensor vertically with
flow in upward direction to maintain solids suspension.
● Gas application
Ensure that the gas pressure/temperature conditions contain sufficient superheat to
prevent dewing or precipitation. If the gas contains vapor or droplets then these may
precipitate, causing instability.
Step 2: Performing a zero point adjustment
The second step in the troubleshooting procedure is to zero point adjust the device. For
further information on zero point adjustment, see Commissioning (Page 51).
Step 3: Calculating the measurement error
The result of the zero point adjustment will show you if the zero point was set under good
and stable conditions.
The lower the obtained value of the parameter Zero Point Standard Deviation, the lower is
the achievable measuring error. For a well-installed flowmeter, the Zero Point Standard
Deviation corresponds to the specified zero point stability for the sensor size, see
Performance (Page 93).
The parameter Zero Point Standard Deviation is located in the Maintenance & Diagnostics
menu in the SIMATIC PDM.
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Operating Instructions, 02/2016, A5E33120874-AC
FC410 with Modbus