Paladon Systems' unique actuator dual spring designs overcome the challenges of unusual control valve thrust requirements
For the last few months Paladon Systems has been busy completing the supply of 25 electro-hydraulic valve positioning systems for the Esso Highlands project in Papua New Guinea. Powered by a ring-main biodegradable fluid supply, the actuators and controls provide precise valve positioning via HART communication protocol for 2” to 8” valves up to 2500 pressure class.
Product Manager Mike Northwood, “One of the biggest challenges on this project was providing linear hydraulic actuators that met the unusual thrust characteristics of the control valves. Twenty three of the valves required a very high break to close thrust but also an extremely low end to close (reseat) thrust. The specifications originally called for double-acting actuators; however, it is was quickly determined that any double-acting actuators that provided sufficient break to close thrust would also provide too much reseat thrust, possibly resulting in damage to the valves. To overcome this we designed spring-return actuators that open the valves on the hydraulic stroke and close them on the spring stroke using springs with very low reseat thrusts. The specifications required that the valves would fail stay-put on loss of the actuator’s hydraulic supply pressure, so we included automatic isolation valves that lock the hydraulic supply pressure in the actuators once pressure from the ring-main circuit was lost and additional circuitry to allow for thermal expansion in the closed system. These units have now been shipped and most already installed. The remaining 2 valves required spring-return fail-open actuators that also had very unusual valve opening thrusts that necessitated a bespoke nested spring arrangement to provide a non-linear actuator thrust output on the valves opening strokes.”
Find out more about Pneumatic & Hydraulic Linear Actuators and Hydraulic Power Units.