The pneumatic diaphragm actuator fitted with top-mounted handwheel is a linear spring-return actuator integrated with a manual operating mechanism on top of the diaphragm housing. It supports both automatic pneumatic modulation and emergency manual operation for linear-stroke control valves.
Pneumatic Diaphragm Actuator with Top-Mounted Handwheel – Working Principle
Normal Operation: When pneumatic signal is applied, air pressure drives the diaphragm to move the pushrod linearly for automatic valve regulation. The handwheel stays in the disengaged idle position without interfering with automatic pneumatic operation.
Emergency Operation: In case of air supply failure, signal loss or actuator maintenance, rotate the top-mounted handwheel to drive the pushrod via lead screw and manually adjust valve opening. It is equipped with a one-way travel stop function to limit maximum valve opening and prevent over-travel.
Available in direct-acting and reverse-acting versions. The built-in spring returns the actuator automatically upon air loss to realize Air-to-Open (FC) / Air-to-Close (FO) fail-safe modes.
A pneumatic actuator converts the energy of compressed air into mechanical motion, enabling the valve to open, close, or continuously modulate its position for reliable and automated valve control. For pneumatic actuator selection and procurement, please contact our technical team and provide the relevant operating parameters so that we can recommend the most suitable actuator model for your application. （Unit: mm）
| Size | Part No | L | H | FC-H1 | FO-H1 | H2 | A | C | D | M | D1 | n-d | E | F | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 22 | XTH22-BOT | 290 | 297 | 90 | 106 | 185 | 250 | 20 | 60 | M8 | 80 | 2-10 | 210 | 250 | |
| 23 | XTH23-BOT | 290 | 326 | 90 | 115 | 185 | 250 | 20 | 60 | M8 | 80 | 2-10 | 210 | 250 | |
| 34 | XTH34-BOT | 365 | 417 | 130 | 170 | 235 | 300 | 22 | 80 | M12X1.25 | 105 | 4-12 | 240 | 300 | |
| 45 | XTH45-BOT | 470 | 525 | 135 | 195 | 322 | 400 | 25 | 95 | M16X1.5 | 118 | 4-14 | 330 | 400 | |
| 56 | XTH56-BOT | 597 | 731 | 170 | 270 | 430 | 500 | 35 | 100 | M20X1.5 | 130 | 4-18 | 375 | 500 |
Pneumatic Diaphragm Actuator with Top-Mounted Handwheel – Key Advantages
Automatic & Manual Operation：Combines automatic pneumatic control with local manual override. In the event of air supply failure, the valve can be operated manually on site, helping maintain process continuity and improving system reliability.
Adjustable Travel Limitation：The integrated mechanical travel stop allows the maximum valve opening to be preset, preventing over-travel, excessive opening and potential damage to the valve trim.
Compact Integrated Design：The handwheel is mounted directly on top of the diaphragm actuator, eliminating additional side clearance and making the actuator suitable for space-restricted installations.
High-Precision Diaphragm Actuation：Retains the advantages of a conventional pneumatic diaphragm actuator, including smooth operation, low hysteresis and high positioning accuracy. A valve positioner can be added for precise proportional control.
Easy On-Site Operation & Maintenance：Manual operation can be performed without removing the actuator, simplifying commissioning, troubleshooting and emergency valve operation while reducing maintenance downtime.
