How-To: Change from Fail Close to Fail Open
Step by Step Instructions:
WARNING: Actuators with preloaded springs are under tension. They can be identified by three long bolts protruding from the bottom of the actuator. These should be removed last, and installed first upon re-assembly.
- With the actuator removed from the valve, unscrew the nuts and bolts on the diaphragm case.
- Lift off the top diaphragm case and remove springs.
- Pull the diaphragm plate assembly consisting of the diaphragm plate, diaphragm, and actuator stem out of the bottom diaphragm case.
- Clamp the bottom section of the actuator stem into a vise using protective jaws, ensuring the actuator stem is not damaged.
- Remove the collar nut.
- Remove the diaphragm plate from the actuator stem, flip upside-down and place them back onto the actuator stem.
- Re-install the collar nut.
- If necessary, apply a suitable lubricant to the actuator stem.
- Place the appropriate springs in the diaphragm plate centering them in the intended recesses.
- Slide the bottom actuator case over the stem, flip the case and diaphragm plate assembly over.
- Place the top of the actuator case onto the assembly. Ensure that the air connections on the cases are correctly aligned with each other.
- Fasten the top and bottom diaphragm cases together using the nuts and bolts.