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3710 and 3720 Positioners
Diagnostic Connections
See figure 16.
For diagnostic testing of control valve packages
(valve, actuator, positioner, and accessories),
special connectors and hardware are available. The
hardware required for diagnostic connections
includes 3/4-inch NPT pipe nipples and pipe tees
with a 1/8-inch NPT pipe bushing for the connector.
The connector consists of a 1/8-inch NPT body and
body protector. If the diagnostic connectors are
ordered for a positioner with gauges, 1/8-inch stems
are also included.
Install connectors and hardware between the
positioner and the actuator.
1. Before assembling the pipe nipple, pipe tee, pipe
bushing, actuator piping, and connector body, apply
sealant (key 64) to all threads.
2. Assemble connectors and hardware. Remove
standard piping connections, if necessary, and install
the diagnostic connections.
D Type 3720: For a diagnostic connection to the
instrument pressure output from the converter
module, remove the 1/8-inch NPT pipe plug (key 86)
from the Type 3722 converter housing. Apply
sealant (key 83) to the threads of the 1/8-inch NPT
connector body and install it directly into the
housing.
D Types 3710, 3720: For diagnostic connections
made up of a pipe nipple, pipe tee, pipe bushing,
and connector body, turn the pipe tee to position the
connector body for easy access when doing
diagnostic testing.
Calibration
The following calibration procedures are for Type
3710 pneumatic positioner adjustment. For the Type
3720 electro-pneumatic positioner, there are no
20
A6045/IL
Figure 17. Proper Cam Position
adjustments within the Type 3722 converter portion
of the positioner. All adjustments are accomplished
within the pneumatic portion of the positioner.
WARNING
During calibration the valve will move.
To avoid personal injury or property
damage caused by the release of
pressure or process fluid, provide
some temporary means of control for
the process.
Setting the Initial Cam Position
Before trying any calibration procedure, follow these
instructions to position the cam (key 36) with respect
to the valve position.
1. Unscrew the four captive cover screws (key 8)
and remove the positioner cover assembly (key 7).
2. See figure 18. Inspect the cam (key 36) and
loosen the cam locknut (key 37).
3. Disconnect the positioner output tubing at the
actuator and attach a regulated air source or other
means of positioning the actuator.
4. Position the actuator to correspond with the initial
valve position at minimum instrument input signal.
Stroke the actuator to the final valve position and
note the direction of actuator shaft rotation. Return
the actuator to its initial valve position.
5. See figure 17. Position the cam on the roller for
the desired input signal range, for example, 0−100%,
and insure that the arrow on the cam corresponds
with the direction of actuator shaft rotation for
Instruction Manual
Form 5300
July 2005
0.8 mm
(0.031 INCH)
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