Yokogawa EJX118A - Manual (Page 33)

<6. Operation>
6-3
IM 01C25H01-01E
(2) When you cannot obtain the Low Range
Value from the actual measured value of
0%;
Adjust the transmitter output to the actual measured
value obtained by a digital manometer or a glass
gauge.
[Example]
The measuring range of 50 to 250 kPa; the actual
measured value of 130 kPa.
130–50
250–50
Actual measured value= x100=40.0%
(=10.4mA)
Turn the screw to match the output signal to the
actual measured value.
6.3 Starting Operation
After completing the zero point adjustment, follow
the procedure below to start operation.
1) Confirm the operating status. If the output
signal exhibits wide fluctuations (hunting) due to
periodic variation in the process pressure, use
the communicator to dampen the transmitter
output signal. Confirm the hunting using a
receiving instrument or the integral indicator,
and set the optimum damping time constant.
2) After confirming the operating status, perform
the following:
IMPORTANT
• Remove the communicator from the terminal
box, and confirm that none of the terminal
screws are loose.
• Close the terminal box cover and the
amplifier cover. Screw each cover in tightly
until it will not turn further.
• There are two covers that must be locked
on the ATEX Flameproof type transmitters.
An Allen head bolt (shrouding bolt) under
the edge of each cover is used to lock the
cover. When the shrouding bolt is driven
counterclockwise with an Allen wrench, the
bolt rotates upward and locks the cover. (See
page 7-3.) After locking the covers, confirm
that they are secure and cannot be opened
by hand.
• Tighten the zero-adjustment cover mounting
screw to secure the cover.
6.4 Shutting Down Operation
Turn off the power.
NOTE
Whenever shutting down the transmitter for a
long period, detach the transmitter (diaphragm
seals) from the tank.
6.5 Venting or Draining
Transmitter Process-
Detector Section
If condensate (or gas) collects in the transmitter
process-detector section, the measured pressure
may be in error. If it is not possible to configure the
piping for self draining (or self-venting) operation,
you will need to loosen the drain (vent) screw on the
flushing connection ring to completely drain (vent)
any stagnated liquid (gas).
However, since draining condensate or bleeding off
gas gives the pressure measurement disturbance,
this should not be done when the loop is in
operation.
WARNING
Since the accumulated liquid (or gas) may be
toxic or otherwise harmful, take appropriate care
to avoid contact with the body, or inhalation of
vapors.
6.5.1 Draining Condensate for Flushing
Connection Ring
1) Gradually open the drain screw to drain from
the flushing connection ring.
2) When the flushing connection ring is completely
drained, close the drain screw.
3) Tighten the drain screw to a torque of 10 N·m
{1 kgf·m}.