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Product category: Process Hardware (Pipes, Nozzles, Heaters, etc)
News Release from: Rotork Controls | Subject: AQ electric actuators
Edited by the Engineeringtalk Editorial Team on 20 July 2001

Electric valve actuators for South West
Water

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Rotork electric valve actuators have been installed throughout an important water quality improvement programme undertaken by South West Water.

Rotork electric valve actuators have been installed throughout an important water quality improvement programme undertaken by South West Water Rotork actuators were specified in accordance with the company's framework agreement with South West Water

The programme of modernisation, which involves the majority of water treatment plants in Devon and Cornwall, has been implemented to improve the efficiency of backwashing processes to optimise the operation of existing sand filters.

This has been achieved by the installation of Rotork AQ electric actuators on new or existing backwashing valves to precisely control their opening and closing speed profiles.

Careful attention to this process prevents any water hydraulic shock effect.

South West Water's process partner Purac is the main contractor for the project at eight filtration plants in Devon.

A typical site is at the Tottiford Reservoir, where two sets of eight filters process up to 32 megalitres a day of water to supply the Teignbridge and Torbay district council areas.

Rotork's scope of supply at Tottiford encompassed the design and fabrication of sixteen completely new actuated valve packages, including installation by Rotork's Retrofit Department.

The Rotork AQ actuators are operated by an ABB Kent Taylor three-term controller under the supervision of a Modicum PLC in a control system package designed and installed by Purac.

Each day at least eight of the filters are backwashed in a sequence by which the actuators are programmed to operate at a graduated speed profile to shut off the water supply, allow in the reverse wash water and finally bring the filter back on line.

The graduated valve opening and closing profiles have been precisely designed to ensure that the risk of hydraulic shocks in the filters is greatly reduced.

The plant is designed to work on a 'stand-alone' basis, although operating data from the PLC is communicated to South West Water's central control at Exeter by telemetry.

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