WellGuard PWG Pneumatic Piston Actuator
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General Description
The WellGuardTM PWG Piston range of pneumatic Control Fluid Powered linear actuators from Bettis Canada Ltd. is designed to be used in conjunction with Bettis valve bonnets to provide open and close control for major brands of API 6A through conduit reverse acting gate valves fitted to oil and gas wellhead Christmas trees and production flow lines. These actuators can also be used with API 6D and ANSI B16.34 valves where the bonnets are built to the Bettis design.
Suitable for onshore and offshore locations and ideal for use in H2S and CO2 applications, the Bettis PWG range of piston actuators provides a simple and reliable valve automation solution. These actuators will be available in 10′′ and 14′′ diameters, suitable for valve sizes 1-13/16′′ thru 4-1/16′′ (18′′ model currently under development).
Operating Principle
Valve actuation is achieved by applying a low pressure (maximum 250 psig) pneumatic control pressure to a piston in a closed housing thereby exerting a force which compresses a spring and extends a valve stem. This action is designed to open a reverse acting gate valve (or close a directing acting gate valve).
The valve is returned to its fail position upon venting the piston pressure. The actuator ensures that a fail position is achieved through the use of valve body pressure acting on the valve stem diameter assisted by coiled springs. The springs provide rapid and reliable valve shutdown when there is little or no valve body or flowline pressure available.
The Bettis PWG actuator can be supplied to API 6A SDV, SSV and BDV to meet the quality assurance and test requirements of API 6A and Q1. The standard actuator can be supplied to meet the NACE MR0175-2000 requirements (optional).