Yokogawa AXFA14G/C - Manual (Page 93)

IM 01E20C02-01E 9-1
9. ACTUAL OPERATION
9. ACTUAL OPERATION
After you have installed the flowtube into the process
piping, wired the input/output terminals, set up the
required parameters, and performed a pre-operation
zero adjustment, the magnetic flowmeter should output
an accurate flow signal from its terminals as soon as
flow of the fluid to be measured begins. This section
describes zero adjustment and the corresponding
procedures.
For F OUNDATION Fieldbus protocol, please refer to IM
01E20F02-01E.
For PROFIBUS PA protocol, please refer to IM
01E20F12-01E.
9.1 Pre-operation Zero
Adjustment
Zero adjustment is carried out to ensure that the output
for zero flow is 0% (i.e., 4 mA). Although adjustment
to zero is performed at the manufacturing plant prior to
shipment, this procedure must be carried out once
again following the installation of piping in order to
match the magnetic flowmeter to its operating condi-
tions.
This section describes the zero adjustment procedure
using display unit switches from the converter and
using the external status input; accordingly, one of
these methods should be selected and implemented.
IMPORTANT
• Zero adjustment should be carried out before
actual operation. Note that setting and update
functions cannot be carried out during this
procedure (i.e., for approximately 30 seconds).
• Zero adjustment should only be carried out
when the flowtube has been filled with
measurement fluid and the fluid velocity is
completely zero by closing the valve.
• Each time that the fluid being measured is
changed, it will be necessary for zero adjust-
ment to be carried out for the new fluid.