Typical causes of air in the liquid
• The entry pipe and sensor have not been properly filled with liquid.
• The pump cavitates, the rotary speed of the pump is too high in relation to the supply of liquid
to the pump.
• The flow rate in the pipe is too high, so components sitting in front of the flowmeter can
cause cavitation.
• If there is a filter installed before the flowmeter, it may be close to blocking, which also can
cause cavitation.
• Liquid flashes to vapor bubbles while passing through partially open valves or orifices.
• The piping on the pump suction side, pump gaskets or the pump itself is not tight. Air gets
sucked into the system due to a low pressure on the pump suction side.
• The piping on the pump suction side, pump gaskets or the pump itself is not tight. Air gets
sucked into the system due to a low pressure on the pump suction side.
Solid particles in the liquid
If the solid particles in a liquid have a density higher than that of the liquid, they can precipitate
inside the sensor and cause instability which leads to a measurement error.
If solid particles are present in the liquid, they must be homogeneously distributed and have
similar density as the liquid. Otherwise they can cause relatively large measurement errors.
It is important that the sensor is installed so that solid particles can easily run out of the sensor.
1. Ensure that the sensor is installed vertically with an upwards flow.
2. Check if solid particles are present in the liquid:
Take a sample of the liquid, fill a glass and see if the solids precipitate.
10.4
Diagnosing with PDM
SIMATIC PDM is a suitable tool for diagnosing the device.
You can use SIMATIC PDM to read all available parameters to a table for analyzing offline, view
online/actual process values and online/actual diagnostic information.
Requirements
The following procedure must be completed before diagnosing:
• Installation of PDM and PDM device driver
• Connection of communications or digital communications interface
Refer to Remote commissioning with PDM FCT010 (Page 50).
Diagnostics and troubleshooting FCT010
10.4 Diagnosing with PDM
SITRANS MASS 2100 & FC300 (FCT010/DSL)
Operating Instructions, 06/2020, A5E39788682-AB
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