The LEO (linear electric operator actuator) is a completely electric actuator designed to be installed on either conventional reverse (fail-closed) or direct-acting (fail-open) gate valves for use on master valves and/or wing valves of Christmas trees and on pipeline and storage facility valves.
Electrical current powers the motor that operates the valve through a gear train and high-efficiency ball screw. A separate electrical current engages the solenoid and latch. When the valve reaches the fully stroked position, the electrical power is disengaged from the motor by means of a position indicator or a timing device within the control panel.
The system also incorporates two additional safety devices:
- An automatic motor shutoff due to excessive current increase is recognized and activated by the control panel.
- A mechanical torque limiter within the gear train provides motor protection.
Interruption of electrical current to the solenoid disengages the latch and allows the coil spring(s) plus any valve body pressure (acting across the cross-sectional area of the stem) to force the gate to the original position. The coil spring(s) in the LEO actuator generates enough force to return to the gate even if the valve body pressure is zero.