Operators manual
© 2017 Honeywell International Inc.
Operators manual underground gas pressure reducing station
Type: COCON 13
Page 12
2.4.4
Pressure
Control
Two
operation
modes
are
possible:
active
and
monitor
control.
Both
modes
operate
identical
and
can
be
reversed
during
testing
and
operation.
During
normal
operation
the
upstream
control
valve
monitors
the
outlet
pressure
in
wide
‐
open
position,
while
the
downstream
valve
reduces
inlet
to
outlet
pressure
in
throttling
position.
Control
has
been
based
upon
cascaded
loops
(with
master
and
slave)
which
have
been
proven
reliable
and
accurate
under
most
operation
conditions.
The
outlet
pressure
depends
upon
the
dome
‐
load
(motorization)
as
set
and
corrected
by
the
pilot.
2.4.5
Active
Control
Fig.
3.3.1
Low
Pressure
If
the
dome
load
(active
motorization)
on
the
active
valve
(1)
exceeds
the
outlet
pressure,
the
diaphragm
(2)
will
move
upward.
This
increases
the
stem
travel
and
allows
the
active
to
compensate
(directly)
for
low
pressure.
High
Pressure