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3710 and 3720 Positioners
NAMEPLATE
AREA
SCREENED
VENT
OPENING
ZERO ADJ PIVOT
SPAN ADJ
SHAFT
(THREADED ROD)
ZERO ADJUSTER
LOCK NUT
ZERO ADJUSTER
NOTES:
1
THE SPAN ADJ ASSY IS MADE UP OF THE RANGE SPRING, SPAN ADJ SHAFT (THREADED ROD), AND SPAN ADJ KNOB.
2
THE SPAN ADJ ASSY FEATURES A RED COLOR-CODED RANGE SPRING FOR A 6 TO 30 PSIG INPUT SIGNAL
W5947
D If the actuator/valve travel, observed in step 5,
stopped short of the required valve position at
maximum input signal, increase the actuator/valve
travel by rotating the positioner span adjustment
knob toward the zero adjustment nut (key 35) to add
active spring coils to the range spring.
D If the actuator/valve travel, observed in step 5,
reaches the required valve position before the input
signal reaches the maximum input signal, decrease
the actuator/valve travel by rotating the positioner
span adjustment knob away from the zero
adjustment nut (key 35) to remove active spring coils
from the range spring.
7. After turning the span adjustment knob to change
22
1
SPAN ADJ ASSY
2
FEEDBACK
ARM ASSY
Figure 19. Features and Adjustments
ACTION BLOCK
MOUNTING SCREW HOLE
MOUNTING SCREW HOLE
CAM
actuator travel, re-zero the positioner using the
procedure given in steps 4 and 5, above.
The outputs of a properly calibrated
positioner will be in the saturated
condition (zero pressure or full supply)
when the valve is fully open or closed.
8. Increase the input signal until the input reaches
the maximum input signal. Observe the
actuator/valve travel as the input increases. Repeat
steps 3 through 8 until the actuator travel
corresponds to the input signal range.
9. Properly align the indicator and replace the
positioner cover assembly.
Instruction Manual
Form 5300
July 2005
SPOOL VALVE
INPUT MODULE
SUMMING BEAM
ASSEMBLY
SUMMING BEAM
FLEXURE
MOUNTING
SCREW
HOLE
Note
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