CALIBRATION
TROUBLESHOOTING CALIBRATION ADJUSTMENTS
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Servo Adjustments (Type AV4 Positioner)
The Type AV4 positioner servo comes from the factory completely
calibrated. The adjustments shown in the following procedures
should only be performed when required.
outlines the
criterion for the adjustments.
The purpose of this procedure is to adjust the servo so that it pro-
duces a 20.7 to 103 kilopascals (three to 15 pounds per square
inch gage) pneumatic signal when pulsing the input. Use the fol-
lowing procedure to perform the check.
1. If electrical connections have not been made, refer to
1. Connect supply air (172 to 1034 kPa (25 to 150 psig)) to the S
port on the manifold (if equipped) or positioner. The minimum sup-
ply pressure must be 34.4 kPa (5.0 psig) above the operating
requirements of the actuator.
2. Apply the supply air to the positioner.
3. Connect a calibrated pressure gage (or some other accurate
pressure measuring device) to the I port. This allows you to moni-
tor the signal pressure during calibration.
4. Adjust the internal pressure to the minimum value (13.8 to
17.0 kPa (2.0 to 2.5 psig)). Do so by closing the
lower
contact
until the pressure stops decreasing.
a. If 13.8 to 17.0 kPa (2.0 to 2.5 psig) pressure is obtained,
proceed to Step 6.
b. If the desired pressure is not obtained, proceed to Step 5.
5. Loosen and back off the minimum locknut. With the
lower
contact closed, rotate the minimum stop screw (clockwise to
increase) until a pressure of 13.8 to 17.0 kPa (2.0 to 2.5 psig) is
obtained. Verify that the hub screw is still in contact with the tip of
the minimum stop screw (Fig.
). Tighten the minimum locknut
and check the pressure.
WARNING
Type AV positioners are suitable for a maximum supply
pressure of 1034 kPa (150 psig). Do not exceed maximum
recommended final control element operating pressure.