Yokogawa EJA110A - Manual (Page 36)

IM 01C21B01-01E 7-4
7. OPERATION
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.
F0706.EPS
Drain screw
Drain plug
Figure 7.5.1 Draining the Transmitter
7.5.2 Venting Gas
1) Gradually open the vent screw to vent gas from the
transmitter pressur-detector section. (See Figure
7.5.2.)
2) When the transmitter is completely vented, close
the vent screw.
3) Tighen the vent screw to a torque of 10 N·m.
When you loosen the vent screw, the gas
escpes in the direction of the arrow.
F0707.EPS
Vent screw
Vent screw
Figure 7.5.2 Venting the Transmitter
7.6 Setting the Range Using the
Range-setting Switch
With actual pressure being applied to the transmitter,
the range-setting switch (push-button) located on the
optional integral indicator plate and the external zero-
adjustment screw allow users to change (re-range) the
low- and high-limit values for the measurement range
(LRV and HRV) without using BT200. However, other
changes in the display settings (scale range and
engineering unit) for the integral indicator requires
BT200.
Follow the procedure below to change the LRV and
HRV settings.
[Example]
Rerange LRV to 0 and HRV to 3 MPa.
1) Connect the transmitter and apparatus as shown in
Figure 9.3.1 and warm up for at least five minutes.
2) Press the range-setting push-button.
The integral indicator then displays “ LSET .”
3) Apply a pressure of 0 kPa (atmospheric pressure) to
the transmitter. (Note 1)
4) Turn the external zero-adjustment screw in the
desired direction. The integral indicator displays the
output signal in %.
(Note 2)
5) Adjust the output signal to 0% (1 V DC) by rotating
the external zero-adjustment screw. Doing so
completes the LRV setting.