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A high-cost-performance spring return pneumatic actuator

The big-size ASD series spring-diaphragm rotary pneumatic actuators refer to the actuator with spring-to-close torque ranging from 1000 Nm to 10000 Nm. The working pressure of the media ranges from 2 to 7 Bar. These actuators, featuring high spring return torque, are suitable for the automated control of large ball valves, butterfly valves, and V-port valves with high requirements of rotational accuracy and stable operation. This actuator employs a spring-diaphragm structure and a crank-rocker mechanism, and adopts the design idea of separating the power medium working chamber from the mechanical transmission mechanism, offering very unique product advantages. The big-size ASD series spring-diaphragm rotary actuators not only exhibit excellent working performance but also demonstrate an exceptionally impressive cost-performance ratio.

Superior cost-performance

The main components of the big-size ASD series spring diaphragm actuators, such as the spring housing (23), diaphragm cover (38), diaphragm retainer (35), and spring retainer (30), are formed by extruding 20# high quality carbon steel plate (1020). This manufacturing method saves material, reduces costs, and results in lighter weight of the actuator. With these unique processing technologies, the big-size ASD series spring diaphragm actuators offer excellent cost-performance. As shown in the table below (market statistical data), under the same output torque (ETC) conditions, the scotch yoke actuator (ASY16-350SR5) weighs 320 kg, while the spring diaphragm actuator (ASD6E) weighs only 201 kg. The scotch yoke actuator (ASY16-350SR5) requires USD 1.01 per output torque (Nm), whereas the spring diaphragm actuator (ASD6E) only needs USD 0.79 per output torque (Nm).

Installations of three kind of pneumatic actuator (scale 1:1)

Excellent work performance

1. Flexible selection of working media

The ASD spring-diaphragm rotary actuator features an independently expandable and contractible media room design, offering flexible selection of working media such as compressed air (no cleaning requirements), water, or mineral-based hydraulic oil.

2. Can operate within the range of -60℃ to 170℃

The independent pressure media room is equipped with a diaphragm of NBR, LNBR or Composite silicone reinforced with nylon66 fabric blend or EPDM4 reinforced with pdyester fabric blend. Equipped with the corresponding diaphragms, these actuators can operate normally within a temperature range from as low as -60°C (-78°F) to as high as 170°C (338°F).

3. Continuity of torque output and smooth start and end

Due to the expandable and contractible of the media room under pressure and the continuous motion of mechanical transmission, the ASD spring diaphragm rotary actuator exhibits strong continuity in its output torque, ensuring valve start and end smoothly.

4. Lighter, faster and high-torque output

ASD spring-diaphragm actuators not only offer a lightweight design with high output torque but also enable fast opening and closing. Under the same output torque conditions, compared to scotch yoke actuators, big-size spring-diaphragm actuators creat an output torque (spring to close) of 10.94 Nm/kg, whereas scotch yoke actuators only provide 6.36 Nm/kg.

5. Removable & Replaceable multiple drive bushing

The drive bushings of the actuator are available with keyed holes, double D holes or double square holes or with the stem of square, star or namur. It is important to note that these drive bushings comply with the 5211 , and are interchangeable, and can be easily replaced at the worksite.

6. Reversible in field fail closed or fail open

The operation of fail closed to fail open can be quickly and easily changed in the field by simply inverting the bushes and the actuator.

7. Travel Stops

The actuators have double adjustable travel stops that allow to be adjusted to the fully open (90°) or the fully closed (0°) within ±5°.

8. Mechanical Lockout

Equipped with locking screws to locked the spring to end position of actuator in case of spring failure.

9. Corrosion Resistant

All the fasteners are with dacromet coating, the parts inside are with electrophoretic coating and the outside parts are with electrophoretic coating + polyester powder coating or PTFE coating. Meet the corrosion protection requirements for moderate corrosion or marine environments.

10. Universal mounting pads for direct mount

The actuator offers a combination of different mounting pads (5211 + JB) that allow you to directly replace existing Spring-Diaphragm Actuator or mount directly to new and existing quarter turn valves.