1. If output pressure level is low, before adjusting, check for leaks in tubing connections between positioner and actuator
and check supply pressure.
2. Make certain there is no process force or pressure in the valve (The valve should be removed or isolated from the
process.)
3. On positioners without gauges, connect gauges to ‘output 1’ and ‘output 2’ lines
4. Remove rubber cap over balance adjustment screw. (See Figure 4.)
5. Apply full actuator operating pressure to positioner supply port.
6. Set input signal to midscale (9 psi for 3-15 psi span). Output pressure level cannot be adjusted with actuator against
valve seat or travel stops. Allow actuator pressure to stabilize.
7. Observe the pressure gauges. If reading is not correct, turn balance adjustment screw about 1/8 turn at a time and
wait about 20-30 seconds for pressure to stabilize (counterclockwise to increase pressure). Continue until output
pressure level of the higher pressure gauge is approximately 80 percent of supply.
8. Replace rubber cap over balance adjustment screw.
Figure 5: Close-up of Gain Adjustment
Figure 6: Gain Adjustment
Gain Adjustment Procedure
The unique gain adjustment on the APEX 8000 positioner provides a means to increase or decrease the
responsiveness of the valve / actuator / positioner system. Increasing gain makes the valve more responsive and
faster, while decreasing gain makes the system less sensitive and slower to respond (with increased damping)
