Table of Contents
Advertisement
FIELD REVERSAL
To change the sensor from direct to reverse acting or vice
versa, disassemble down to valve housing assembly.
Remove the locking screw (detail 8) and spring seat (detail
9). With a long allen wrench, remove the set screw (detail
33) from inside the stem.
Remove the flanges. Invert the valve housing assembly
and re-install the set screw all the way to the end of the
stem. Replace the flanges and secure with screws.
Reassemble the pressure assembly to the valve housing. DO
NOT replace the spring seat or screw at this time. Apply a 5
psi process pressure to the HP process port. Apply a 30 psi
pressure to the control port. Insert the allen wrench at point
"P." Apply approximately a one pound downward force on
the allen wrench and slowly turn the set screw clockwise
until the sensor vents the control pressure on direct-acting
models. Then turn one-half turn further. On reverse acting
models, first turn the set screw clockwise until the venting
stops and then turn counterclockwise until the sensor vents
once more. Then turn one-half turn further. Apply Loctite to
set screw.
Complete the re-assembly per previous instructions and
recalibrate the sensor.
ADJUSTMENTS
Setpoint
1. Remove cap screw.
2. Apply operating control pressure to inlet port through
a .8 mm (.032") diameter or smaller orifice. Control
pressure and orifice size must be the same as that used
during normal operation.
Direct Acting
Figure 3
Table 3
Model No.
Dim. "A," mm (In.)
84374-A, C
1.65 (.065)
84374-B
.51 (.020)
3. Apply process pressure at desired setpoint to the
process port.
4. Insert a 1/8" hex wrench into the adjustment screw
and turn screw counterclockwise (clockwise for
reverse-acting units) until the valve snaps open and
sensor vents. If the valve is already open, turn the
screw clockwise (counterclockwise for reverse-acting
units) until the valve closes, then reverse direction and
turn screw until valve snaps open and vents.
5. Check operation and trim as necessary.
6. Replace the cap screw.
Differential (Applicable to Auto Reset versions only)
CAUTION: Sensor will not vent if differential
adjustment screw is turned clockwise to its
maximum insertion into the valve housing. Do not
set differential below minimum recommended value
as shown in graphs.
1. Apply operating control pressure to inlet port through
a .8 mm (.032") diameter or smaller orifice. Control
pressure and orifice size must be the same as that used
during normal operation.
2. Cycle measured pressure at the process port and
adjust the differential adjustment screw until desired
differential is obtained. Differential is increased by
turning the screw counterclockwise.
Reverse Acting
Dim. "B," mm (In.)
2.79 (.110)
2.0 (.078)
6
Advertisement
Table of Contents
