Yokogawa ADMAG AXF - Manual (Page 88)

IM 1E10C1-E 9-6
9. MAINTENANCE
9.2.2 Unstable Zero
Examine whether or not the
valves leak.
• Confirm the flow tube
grounding.
• Confirm whether or not the
grounding wire is
disconnected from the earth
terminal.
Examine whether or not the
meter tube is filled with liquid
and the liquid does not contain
bubbles.
Recheck liquid property.
Insulation deterioration is
suspected.
Contact the nearest Yokogawa
office or service center.
NO
NO
YES
YES
NO NO
NO
NO
It is better to provide a vent
hole on the downstream
side of the flow tube to
check bubbles.
Change the piping or
mounting to fill the flow
tube with the liquid.
Vertical mounting is
effective.
NO
Mount a defoaming device
on the upstream side of the
flow tube.
Stop the leak by repairing
valves.
Complete grounding (The
resistance must be 100
Ω or
less.) See “3.2.1 Protective
Ground”.
a. Insure that the liquid
conductivity does not
change beyond fluid
limits.
b. Do not use the ADMAG
SE for liquid has
conductivity below
5
µ S/cm.
c. Decrease flow velocity
near the conductivity low
limit as much as possible.
• Remove dirt and scale on
near electrodes.
• Change to vertical
mounting.
Sufficiently shield the flow
tube.
Locate the flow tube as far
as possible from these
equipments.
NO
YES
YES
YES
Are bubbles
contained in the liquid?
Is the flow tube filled
with liquid completely?
Are valves leaking?
Is grounding complete?
• Does the liquid
conductivity vary or
is it easy to change?
• Is liquid conductivity
sometimes below
5
µ S/cm?
Is the liquid
likely to cause deposits?
Is the flowmeter
located near motors,
transformers, or other
electric equipmets.
START
*1
*1
YES
YES