Flowserve APEX W7000 Pneumatic Positioner - Manual (Page 3)

3
Calibration Procedure:
1. Apply 0% input signal (0% = 20 kPa, 3 psi, or 4 mA).
2. Wait for steady state. It is important to wait for steady state. On very large actuators, it can take minutes to
establish.
3. Loosen locking screws A and D by about 1 turn. Locking screw D is the angled screw, just above and to the right
of the Zero thumbwheel. If the locking screws are excessively loose, you risk introducing unwanted movement.
4. Adjust “ZERO” position using thumbwheel B. You may find it convenient to turn the thumbwheel by using a
screwdriver blade in the slots.

If using a spring-return actuator, the zero point should be the point at which the positioner output pressure is
still zero, but just begins to increase on any tiny increase of signal. This enables all available spring forces to
be applied to move the valve to its safe position.

If using a double-acting actuator, the zero point is the point at which the actuator will move on any signal
increase.

If the valve jumps upscale on the initial incremental signal change, the cam is likely misaligned. See page 2
for cam alignment instructions. Revivify cam alignment, then recheck the zero adjustment

4b.Retighten locking screw D to lock the Zero Nut. DO not retighten A at this time
5. Apply 100% input signal (100% = 100 kPa, 15 psi, or 20 mA).
6. Wait for steady state.
7. Adjust the “SPAN” setting by turning screw C with a flat-blade screwdriver. This adjustment is accessed by
removing the rubber plug in the bottom of the case. The valve should stroke to 100% of desired travel, but
should not be loaded against a mechanical stop. Slightly decrease the signal to verify that the valve is tracking
the signal value. Span is calibrated when the valve strokes to 100% at exactly 100% signal:
8. Lock the calibration mechanism in place by tightening locking screw A.
9. Apply 0% signal and verify zero position. Recalibrate if necessary.