Article How It Works: Actuators
Automate valves so that no human interaction with the package is required for cycling.
Cameron provides a variety of subsea choke actuators, including hydraulic "fail fixed" actuators in operating pressures of 3,000 and 5,000 psi, which are compatible with water or mineral-oil-based control fluids and optional stand-alone DC electric actuators.
The Aqua-Torq hydraulic stepping choke actuator, typically used on our clamp-style insert retrievable chokes, is designed to provide precise incremental steps from open to closed. Oil-filled and pressure compensated, this subsea choke actuator incorporates a marine growth-resistant local-position indicator and is available with an internal linear variable differential transformer (LVDT). The actuator is fitted with flushing ports, and the customer hydraulic interface usually is located near the weld tails on the stab-mate hydraulic couplers.
Our SLCA offering is a more compact hydraulic stepping actuator, developed for use on non-retrievable chokes and now also used on Cameron's compact choke and CC80SR. The SLCA has two single-acting piston-pawl assemblies—one for open and one for closed. It is oil-filled and pressure-compensated with a remote-position feedback via an LVDT, a marine-growth-resistant local-position indicator and an ROV override.
Our accurate LVDT electronic remote position feedback sensor is available for both Aqua-Torq and SLCA actuators. These non-contacting position sensors are seal welded, digitally calibrated and available in analog (4-20mA) and digital (CANBus) output designs. Reliable, field-proven, and individually hyperbarically tested to 11,400-foot (3475-meter) water depths, our LVDTs provide accurate choke position feedback to the subsea production control system
For use with Cameron non-retrievable chokes with either diver or ROV operation, our RD250 ROV gearbox is oil-filled and pressure-compensated. It also has an external marine-growth-resistant local-position indicator, which allows the choke setting to be read easily. The gearbox is available with LVDT position feedback.
| Water depths
||9,800 ft [3,000 m]
|Hydraulic operating pressure
||3,000 or 5,000 psi
|Hydraulic operating fluid
||Water- or oil-based
|Manual or ROV override
||API Spec 17D Class 3 or 4; High torque; special
||LVDT analog (4 to 20 mA); digital CANbus