Introduction

Pneumatic actuators are widely used in modern industrial automation to open and close valves automatically. The AT pneumatic actuator is a common example. Adjusting its limits essentially means setting the actuator travel range, or, in plain terms, controlling how far the valve opens. Correctly set limits help the valve work properly and prevent damage from excessive opening or closing. This article breaks the adjustment procedure into 6 steps to help you set the limits accurately.

1. Before Adjustment: Disconnect the Air Supply

Safety always comes first:

  • Disconnect the air supply and make sure the actuator is stopped.
  • Confirm that the actuator cannot move unexpectedly during adjustment.

2. Position Manually and Determine the Adjustment Range

After disconnecting the air, establish the limit reference manually:

  • Manually turn the pneumatic actuator to the valve's fully open or fully closed position.
  • The purpose of this step is to establish the limit adjustment range.

3. Open the Limit Switch Box

Next, open the limit switch box on the actuator:

  • Loosen the screws on the limit switch box.
  • Remove the cover to expose the limit switch adjustment mechanism.

4. Adjust the Two Microswitches: The Key Step

This is the central part of the procedure. Inside the limit switch box are two microswitches that correspond to the actuator's cams:

  • Adjust the positions of the two microswitches to establish the limit switches' actuation points.
  • Each actuation point corresponds to a specific valve opening.
  • Accurate positioning of these two microswitches is what ensures that the valve reaches its fully open and fully closed positions.

5. Replace and Secure the Cover

After completing the adjustment, restore the protection of the limit switch box:

  • Close the limit switch box cover.
  • Tighten the screws on the limit switch box to prevent loosening.

6. Restore the Air Supply and Check Operation

Finally, restore operating conditions and verify the result:

  • Connect the air supply to return the pneumatic actuator to normal operation.
  • Carefully check the limit switches and make sure the valve opening meets the intended setting.
  • If anything is abnormal, readjust the microswitch positions until the requirements are met.

Conclusion

The essential sequence for adjusting an AT pneumatic actuator's limits is simple: disconnect the air → establish the range → adjust the microswitches → verify. Remember the two key components, the microswitches and cams: their relative positions determine the valve-position actuation points. Proper limit adjustment helps keep the valve stable and reliable within its normal operating range. For technical assistance with AT actuator limit adjustment, contact our professional service team.

Zhejiang HES Automatic Instrument & Valve Co., Ltd. Founded in 1989 · Over thirty years focused on pneumatic actuators and pneumatic valves. Official website: www.hesvalve.com