Yokogawa EJA310A - Manual (Page 32)

IM 01C21D01-01E 7-4
7. OPERATION
7.3 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 BT200 to
dampen the transmitter output signal. Confirm the
hunting using a receiving instrument or the integral
indicator, and set the optimum damping time
constant. See Subsection 8.3.3 (3), “Damping Time
Constant Setup.”
2) After confirming the operating status, perform the
following.
IMPORTANT
• Remove the BT200 from the terminal box, and
confirm that none of the terminal screws are
loosened.
• Close the terminal box cover and the amplifier
cover. Screw each cover in tightly until it will
not turn further.
• Two covers are required to be locked on the
CENELEC and IECEx Flameproof type trans-
mitters. An Allen head bolts (shrouding bolts)
are provided under edge of the each cover for
locking. When a shrouding bolts are driven
counterclockwise by an Allen wrench, it is
coming out and locks up a cover. (See page 9-
3) After locking, the covers should be con-
firmed not to be opened by hand.
• Tighten the zero-adjustment cover mounting
screw to fix the cover in position.
7.4 Shutting Down Operation
Shut down the transmitter operation as follows.
1) Turn off the power.
2) Close the stop valve.
3) Close the tap valve.
NOTE
Whenever shutting down the transmitter for a
long period, remove any process fluid from the
transmitter pressure-detector section.
7.5 Venting or Draining Transmit-
ter Pressure-detector Section
Since this transmitter is designed to be self-draining
and self-venting with vertical impulse piping connec-
tions, neither draining nor venting will be required if
the impulse piping is configured appropriately for self-
draining or self-venting operation.
If condensate (or gas) collects in the transmitter
pressure-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 transmitter
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.
7.5.1 Draining Condensate
1) Gradually open the drain screw or drain plug and
drain the transmitter pressure-detector section. (See
Figure 7.5.1.)
2) When all accumulated liquid is completely re-
moved, close the drain screw or drain plug.
3) Tighten the drain screw to a torque of 10 N·m, and
the drain plug to a torque of 34 to 39 N·m.
When you loosen the drain screw or drain
plug, the accumulated liquid will be expelled
in the direction of the arrow.
F0707.EPS
Drain screw
Drain plug
Figure 7.5.1 Draining the Transmitter