A Rotork CVA electric control valve actuator has been installed in a 400MW power plant in New Hampshire, USA, which burns both natural gas and low-sulphur fuel oil, to help to reduce maintenance costs and improve accuracy in a demanding outdoor fuel oil flow control application.

The Rotork quarter-turn actuator (model CVQ 1200) in a NEMA 6 enclosure was installed in June. It replaced a traditional I/P positioner and spring diaphragm pneumatic actuator operating a 6in class 150 ball valve.

The valve and actuator are located outdoors and control the flow from a fuel oil day tank to fuel oil pumps. The valve modulates frequently to maintain the correct flow as the load on the unit changes. After initial set-up, they conducted several tests of the CVQ’s performance from the control room using their DCS.

The position was monitored in the field using a PDA. They found that their CVQ model responded very accurately, with no deviation, to a wide range of different DCS set points, matching them all. Plant personnel also did extensive tests on the fail-closed feature and verified proper performance in both loss-of-power and loss-of-input-signal situations.