In developing the G-Series actuators, Bettis improved a basic concept - the reaction bar, by adding state-of-the-art Powr-Swivl, replaceable bearings that feature an efficient wear and corrosion resistant coating system, and tension rod compressed spring. This enhanced design significantly improves efficiency, reduces wear and extends the actuator's life. Typical applications would include the automation of ball, butterfly and plug valves, louvers and dampers and quarter-turn mechanisms.
The piston rod connection is contained by the guide block, which is supported by a high strength alloy steel reaction bar treated to provide a highly corrosion and wear-resistant finish. The superior surface finishes and self-lubricating bearings maximise the transfer of input energy directly to the valve stem. The tension-loaded spring minimises radial loads on the piston rod, further enhancing efficiency.
G-Series models are qualified by accelerated wear testing. The actual service life may be predicted based upon specific application parameters and environmental conditions. Proper actuator selection, enhanced by proprietary data analysis methods, allows optimum performance and operating economy. Low friction, permanently lubricated, high performance bearings protect sliding and rotating components, significantly extending actuator life.
G-Series actuators incorporate protective internal and external coatings, assuring the actuator's reliable operation in the harshest of environments. The actuator exhibits excellent corrosion resistance, confirmed by salt spray testing per ASTM B117 criteria. Construction features prevent water ingress, allowing the actuators to meet IP66 and IP67M specifications and severe high-pressure water deluge test.
Safe installation and removal of the spring module is facilitated by the design. It incorporates Bettis' Tension-Lok, which allows for the removal of the spring module in a manner that eliminates accidental release of the spring force. Each module is tagged with detailed product information, minimising the potential for incorrect installation, operation, or misapplication of a reconfigured actuator.
The ease of interchanging the power and spring modules allows quick reversal of the 'fail-safe' mode, while providing for the addition of overrides, accessories and other modules. For instance, the actuator may be easily altered from a single-acting to double-acting power cylinder configuration, and/or a hydraulic manual override may be added after the actuator has been installed.
Field serviceable modules include the drive, power, spring and override. They are removable, serviceable and interchangeable without removing the actuator from the valve. This procedure requires no special tools or disassembly of any module, reducing the required plant shutdown time for service. Modules may be replaced as an assembly or serviced at the client's maintenance facility - and all modules may be purchased separately or in any combination. This feature allows reduced parts and spares inventory at the distribution facility, while increasing the availability of different model configurations.
For more information contact Emerson trading as El-o-Matic, 011 974 3336.
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