The COMPACT Quarter-turn Rack and Pinion Pneumatic Actuator

The Habonim COMPACT actuator is a quarter-turn rack and pinion pneumatic actuator that doubles the torque of conventional pneumatic actuators. Habonim's patented four piston design, which generates torque around a centrally located piston, is responsible for superior performance, translating to double the power for the same size actuator or half the size for the same power. 

The COMPACT has four small cylinders, one on each of the cube's four sides. The smaller pinion and minimized travel distance of the pistons in the COMPACT require less air pressure to produce the same torque output as a larger double piston actuator. As a result, there's a reduction in emergency shutdown response, air consumption during operation, and maintenance.  Habonim's unique quarter-turn COMPACT actuators have the superior performance of twice the torque per size, much longer cycling before any care, high opening and closing speed, and exceptional durability in the most demanding industrial environments. 

STANDARD ACTUATOR FEATURES

NAMUR & ISO interface

A wide range of accessories such as solenoids, positioners, and limit switches are available for direct mounting to the COMPACT actuator, and any accessory with ISO 5211 and VDI/VDE 3845 (NAMUR) will mount to the actuator. 

NAMUR VDI/VDE 3845

This standard specifies various accessories with VDI/VDE interfaces, such as limit switches, pucks, indicators, and positioners, with simple mounting onto the actuator top face. 

NAMUR solenoid mounting

One of the four actuator covers available includes a pad for solenoid mounting per the NAMUR international standard. Any solenoid that conforms to the NAMUR interface can be directly mounted to the actuators, simplifying solenoid installation and eliminating the need for additional piping. Because the pressurized air supply is available at the port entrance, it also allows for quick actuation response. 

ISO 5211

The actuator bottom flange conforms to the ISO 5211 international standard and includes a star-shaped female drive to accommodate a wide range of valve output shafts. The valve can be attached to the actuator with a bracket or mounted directly onto the actuator using one of the ISO hole patterns.

COMPACT actuators are part of control packages in various industries and providing superior performance in the cycle times, size, weight, compressed-air consumption, and reliability in high cyclic applications. 

For more information in New England, contact:

Piping Specialties / PSI Controls
https://psi-team.com
800-223-1468

Types of Pneumatic Valve Actuators

Scotch-yoke actuators (Morin)

Pneumatic valve actuators all provide the same function:  They convert air pressure to rotational

movement and are designed to open, close, or position a quarter-turn valve.  These include ball valves, plug valves, butterfly valves, or other types of 90 degree rotational valves.

The basic design variations of pneumatic valve actuators are as follows:

• Rack and pinion
• Scotch-yoke
• Rotary vane

Let's review each of these in detail:

Rack and Pinion Actuators

Rack and pinion actuator (Unitorq)

These actuators are sometimes referred to as, “lunch box,” because they, well, look like a lunch box. This actuator uses opposing pistons with integral gears to engage a pinion gear shaft to produce rotation. They are usually more compressed than a scotch yoke, have standardized mounting patterns, and produce output torques suitable for small-to-medium sized valves.  Rack and pinion nearly always include standard bolting and coupling patterns to directly attach a valve, solenoid, limit switch or positioner.  One of their features include several smaller coil springs mounted internally, which provide the torque to return the valve to its starting position.

Scotch-yoke Actuators 

Scotch-yoke actuators internal view.

These actuators come in a multitude of sizes, but are usually used on larger valves because they can produce a very high torque output.  They employ a pneumatic piston mechanism to transfer movement to a linear push rod.  That rod, in turn, engages a pivoting lever arm to provide rotation. Spring return units have a large return spring module mounted on the opposite end of the piston mechanism working directly against the pressurized cylinder.

Rotary Vane Actuators 

Rotary vane actuator animation.

These actuators are usually used when the application requires a significant space savings.  They take up less space when comparing size-to-torque with rack and pinion and scotch yoke. Rotary van actuators also benefit from a reputation of longevity.  They contain fewer moving parts than other types of pneumatic valve actuators.  Rotary vane actuators use externally mounted, helically wound "clock springs" for their spring return mechanism.

These style of valve actuators can all be secured with direct acting or spring return versions. Direct acting actuators use the air supply to move the actuator in both directs (open and close). Spring return actuators, as the name describes, uses springs to move the actuator back to its "resting" state. Converting a version from direct acting to spring return is done through simple modifications, typically just adding an external spring module, or removing the end caps from rack and pinion actuators and installing several coil springs.

When considering the choice of pneumatic valve actuators, your decision comes down to size, power, torque curve and the ease of adding peripherals. To ensure that your valve actuation package will be optimized for safety, longevity, and performance, the advice of a qualified valve automation expert should be sought out. That expert will be able to help you with the best selection of the appropriate valve actuator for any quarter turn valve application.

For more information on valve actuation, contact Piping Specialties, Inc.
https://psi-team.com
800-223-1468