User`s manual

<7. Operation>
7-3
IM 01C25B01-01E
7.2 Zero Point Adjustment
After completing preparations for operating the
transmitter, adjust the zero point.
Zero point adjustment can be done by turning the
transmitter’s zero-adjustment screw or by using
the communicator. This section describes the
procedure for the zero-adjustment screw. For the
communicator procedure, see the communication
manual.
IMPORTANT
Do not turn off the power to the transmitter
immediately after performing a zero point
adjustment. Powering off within 30 seconds of
performing this procedure will return the zero
point to its previous setting.
NOTE
Before performing this adjustment, make sure
that the external zero adjustment function has
NOT been disabled by a parameter setting.
To check the output signal, use a digital multimeter,
calibrator, or communicator.
7.2.1 Adjusting Zero Point for Differential
Pressure Transmitters
Before adjusting zero point, make sure that the
equalizingvalveisopen.
Zero-adjustment
screw cover
F0705.ai
Figure 7.4 External Zero Adjustment Screw
The zero-adjustment screw is located inside the
cover.
Use a slotted screwdriver to turn the zero-
adjustmentscrew.Equalizethetransmitter,then
turn the screw clockwise to increase the output or
counterclockwise to decrease the output. The zero
point adjustment can be made with a resolution
of 0.01% of the setting range. The degree of zero
adjustments varies with the screw turning speed;
turnthescrewslowlytomakeaneadjustment,
quicklytomakearoughadjustment.
When using differential pressure transmitters for
level measurement and if you cannot obtain the
lower range value from the actual measurement
value of 0%, refer to subsection 7.2.2(2).
7.2.2 Adjusting Zero Point for Gauge/
AbsolutePressureTransmitters
(1) WhenyoucanobtaintheLowRangeValue
from the actual measured value of 0% (0
kPa,atmosphericpressure);
For pressure measurement using gauge pressure
transmitters, follow the steps below before
performing zero point adjustment.
1) Close the tap valve (main valve).
2) Loosenthellplugsothatthepressureapplied
to the transmitter is only the head of the seal
liquid.
3) Adjust the zero point at this status.
4) Aftertheadjustment,closethellplugandthen
gradually open the tap valve.
Use a slotted screwdriver to turn the zero-
adjustment screw. Turn the screw clockwise
to increase the output or counterclockwise to
decrease the output. The zero point adjustment can
be made with a resolution of 0.01% of the setting
range. Since the degree of the zero adjustment
varies with the screw turning speed, turn the screw
slowlytomakeaneadjustmentandquicklyto
make a rough adjustment.