Rotork-Hiller received an enquiry to build a fast-acting failsafe stop valve actuator for a plant firefighting system demanded an exceptionally innovative design solution. The specification called for a very compact pneumatically operated actuator, with no springs for the failsafe function, necessitating the provision of a stored energy accumulator.
The addition of a conventional accumulator would have exceeded the dimensional constraints of the specification, so the engineers conceived a radical new design which incorporated the accumulator within the pneumatic actuator. The design not only eliminated the size problem but also freed-up additional space for mounting the controls to the actuator.
These controls include filters, regulators, solenoid valves and pressure switches, contained within overall actuator dimensions of 470 x 584 x 680 mm. The controls reduce the customer’s supply pressure of 45 Barg to 31 Barg g, which is pumped into the accumulator to provide approximately 4.4 litres of storage capacity. The actuator delivers a maximum thrust of 27,617N.