18
R121
Types EZH and EZHSO
Europe, Middle East and
Africa Only
SHUTDOWN
If the pilot bleed control line pressure is shut
down first, the downstream system may be
subjected to full inlet pressure (P
u
).
1. If the pilot setting must be disturbed, be sure to keep
some tension on the spring. This will prevent trapping
inlet pressure during blow down.
2. Slowly close the valves in the following order:
- Inlet block valve
- Outlet block valve
- Control line valve(s), if used
3. Open the vent valves to depressurize the system.
STAGES 2 AND 3
TRIGGERED
POSITION
Travel
stop
Travel
stop
Travel
stop
STAGE 1
Figure 15. Setpoint Verification Phase
Type PRX Pilot Adjustment
To adjust a standard Type PRX pilot, loosen the locknut
and turn the adjusting screw.
Turning the adjusting screw clockwise into the spring case
increases the spring compression and pressure setting.
Turning the adjusting screw counter clockwise decreases
the spring compression and pressure setting.
When the required pressure setting is maintained for
several minutes, tighten the locknut to lock the adjusting
screw in position.
Type PRX Pilot Restrictor and Damper
Screw Adjustment
Note
Recommended initial setting of the restrictor
screw is turned completely in (clockwise)
and then turned out 1/2 turn. The damper
screw initial setting is turned completely out
(counter clockwise).
The Type PRX/125 (upstream monitor pilot in
working monitor installations) does not have
a restrictor screw.
The restrictor screw of the Type PRX pilot can be used if
there is hunting of the set pressure. Slowly turning out the
restrictor screw (counterclockwise) will help steady the
set pressure.
Turning out the restrictor screw will slightly decrease set
pressure, so adjustment of the pilot adjusting screw may
be necessary.
The damper screw can be turned in (clockwise) to slow the
response of the regulator. It is advisable that adjustment of
the damper and restrictor screws be limited to 1/4 turn at a
time to observe the response of the regulator(s).
CAUTION
!
