The V&A Procontrol VP series SIL 3 all steel pneumatic quarter turn actuator is available in double acting and spring return configurations. The design of this model actuator is intended for use where quarter-turn valves need to be controlled, requiring high torque and where a compact actuator design is needed.
The actuator offers high torques up to 400 000 Nm and can be used for both on-off and modulating control. The Scotch Yoke principle of the design gives high torque, precise control and smooth travel at the end positions.
Various options are available including manual override, extra corrosion protection, epoxy finish, low temperature and high temperature versions.
Modular construction
Our current range of scotch yoke actuators consists of various centre body sizes. The centre bodies have been designed to accommodate the widest variety of pneumatic and hydraulic power cylinders together with the widest variety of spring containers.
The power cylinders can be assembled to either or both sides of the centre body. The spring containers can be assembled onto either side of the centre body thus allowing for the fail open or fail close emergency operation. The manual overrides can be assembled onto either side of the centre body. Our modular construction and stocking availability enables us to meet short deliveries.
Scotch yoke principle
The Scotch yoke principle is characterised by its high torque when required - at the beginning and end of each operation. This increases safety, especially in applications where a valve remains stationary throughout long periods. The design yields a long life and offers good regulating features. There is no play in force transmission and low friction because the transmission passes over bearings. The favourable force transmission gives good operating characteristics in the regulation area. This provides lower turning speed when approaching the end positions.
Scotch yoke mechanisms and torque curves
Cantered yoke
The canted scotch yoke is ideal when the valve torque requirements are highest at the beginning (valve unseating) and the end position (valve reseating) of the valve 90 rotation. The cantered scotch yoke mechanism covers most butterfly valve torque requirements.
Symmetric yoke
The symmetric scotch yoke is ideal when the valve torque requirements are highest during the intermediate positions of the valves rotation (running). The symmetric scotch yoke is the most suitable yoke design for modulating service.
The symmetric scotch yoke mechanism is normally used for plug metal seated ball valves and control valves.
V&A Procontrol key design features
* Modular construction allowing for complete interchangeability.
* Weatherproof fabricated carbon steel housing ensures light weight and high strength.
* ISO 5211 flange connection.
* Stainless steel position indicator complete with VDI/VDE 3845 NAMUR drive slot for monitoring devices.
* Standard heavy duty modulating service canted and symmetric steel scotch yoke mechanism to suit most valve torque requirements.
* High strength heavy duty alloy steel chromium plated transversal thrust reaction bar.
* Standard pneumatic cylinder, polished with electro less nickel plated internal coating ensures maximum protection against corrosion, and longer sealing life suitable for supply pressure of up to 12 bar design.
* High pressure gas pneumatic cylinder, in standard carbon steel for sweet or inert gas application, or special application carbon steel for sour gas supply medium, polished with electro less nickel plated internal coating protection against corrosion, suitable for supply pressure of up to 160 bar design.
* Carbon steel piston supported by high strength alloy steel chromium plated piston rod ensure corrosion resistant durability.
* Alloy steel galvanised end stoppers to allow for corrosion resistant fine valve position adjustment + or - 5%.
* Emergency manual overrides available are standard jack screw and declutchable hand wheels or hydraulic hand pump.
* Special cylinder and sealing materials available for special applications.
* Standard operating temperature range: -29°C/+90°C.
* Actuator torque output up to 400 000 Nm.
* Low temperature arctic environment application available.
For more information contact Valve & Automation, +27 (0)11 397 2833, [email protected], www.valve.co.za
| Tel: | +27 31 579 2593 |
| Email: | [email protected] |
| www: | www.valve.co.za |
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