Fluid Components International CMF Series Manual Electronics Setup and Menus - Manual (Page 25)

T. s.
Fluid Components Intl
Document 06EN003327 Rev. - 75 FlexCOR
™
Model CMF Series
8.2 Check for air in the
system
In case of large air collections non-homogenesously distributed in the sensor, the air in the liquid
can disturb the flowmeter and lead to incorrect measurement, whereas homogenesously
distributed air and solids will not disturb measurement.
1) 0-point unstable or exceeding limit (SIGMA LIMIT, refer to reset menu)
2) Measurement of mass flow rate incorrect ?
3) Output signal unstable
4) Error symbol on (type W31, W34, F70, F71)
If one or more of the above symptoms is observed, the cause can be that there is air in the liquid.
Air in the system can be checked through the following tests:
1. Use of Service Mode
Go to the service mode menu and read the values under the menu driver amplitude. Compare
the values with the table listed in section 7.5. If the current is higher than specified it might be
because there are air bubbles in the liquid.
2. Increase of pump pressure
Close the valve, if any, after the sensor. Start the pump and consequently increase the pump
pressure. If the 0-point becomes more stable there are non-homogenseously distributed air
bubbles in the system.
3. Connection of pick-up signals in parallel (only possible for 19“ versions)
The fault can also be found by connecting pick-up 1 and pick-up 2 in parallel. Move the leads on
terminal 85 to terminal 87 on the connection PCB. This will send the same pick-up signal into both
channels in the converter.
If the 0-point becomes more stable by one of the above mentioned examples the conclusion is
that there is air in the system which affects the flowmeter operation.
Air generation souces
The air can typically be generated by the following causes:
1) Suction pressure of pump too low (pump cavitates)
2) Blocked filter or other obstruction ahead of sensor. This can produce cavitation and air
formation
3) Volatile liquid producing air bubbles at low pressure
4) Pressure in sensor too low because too low a pressure in the piping after the sensor
5) Incorrect location of sensor, refer to Chapter 4 "Installation of sensor".
8.3 Check of 0-point
accuracy
Check whether the 0-point is within the accuracy specifications given by Fluid Components Intl.
Check as follows:
Go to the basic settings menu, set low flow cut-off to 0%. Go to totalizer 1, select bidirectional mode
and select massflow.
Go back to operator menu, reset the totalizer 1 (if selected in the operator menu, otherwise reset
the totalizer in the reset menu).
Go to totalizer 1 in the operator menu and monitor the value. The totalizer now displays the actual
0-point of the system. Read the totalizer value after 1 min. mutiply the value with 60, this will give
the value xxxx.x kg/h. This can for the sensor dimension in question be compared with the
specifications given under Section 2.3 “Meter uncertainty”, max. zero point error.