IM 01E20D01-01E
5-11
5.  MAINTENANCE
5.9.2 Unstable Zero
START
Check for the presence of valve 
leakage.
• Confirm the flowmeter grounding. 
• Confirm whether or not the 
grounding wire is disconnected 
from the earth flange.
Recheck the fluid to be measured.
Particular care must be taken in the case 
of horizontal mounting. In order to ensure 
complete filling of the tube, either adjust 
the mounting position or switch to vertical 
mounting.
Install a defoaming device on the 
flowtube’s upstream side.
Replace the valve(s).
Completely ground the converter and  
flowtube (Refer to the section on 
grounding in the relevant user's manual.)
• Ensure that the fluid’s conductivity 
changes as little as possible.
• Do not use the meter when fluid 
conductivity is out of limits.
• Whenever possible, reduce the flow 
velocity to being in the vicinity of the 
lower conductivity limit.
• Remove dirt and scale of and near 
electrodes. 
• Use a soft brush or cloth to perform 
scale removal, and make sure that 
the lining is not damaged.
Provide the meter with sufficient 
shielding or move it away from the 
electrical equipment
NO
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
YES
YES
Are there bubbles 
in the fluid?
Are valves leaking?
Is the fluid likely to 
contain deposits?
• Does the fluid’s 
  conductivity vary?
• Is the fluid conductivity
  within the limits?
Is the flowtube
completely full of fluid?
Is the flowmeter properly
grounded?
Contact a service center.
*1: When checking for bubbles, it is 
convenient if there is a gas vent hole  
on the flowtube’s downstream side.
*1
Investigate whether or not the flowtube 
is filled with fluid and that it is free of 
bubbles.
Is the flowmeter
located near motors, transformers,
or electric equipment?
F0522.EPS