Storm tanks at a North West Water sewage treatment works have gone over to automatic operation with a compact two-wire package installed by Rotork Actuation.
The installation at the Saddleworth Moor plant now has level detection triggered valve sequencing on the tanks, with local computerised control.
The system uses a Pakscan 2S sequencer master station to distribute the process signals between a Miltronics ultrasonic level sensor and two IQ Range intelligent electric valve actuators connected on a common two-wire loop.
When storms raise effluent levels over a predetermined limit, flows spill over a weir, and into the storm tanks which used to be emptied manually.
First, the level sensor detects when the intake flow has dropped back to a preset level. At this point a signal is sent to the master station, triggering a time lapse period after which the IQ actuators open the storm tank outlet valves by 25%, enabling the collected effluent to begin to enter the treatment works.
Should the inlet level begin to rise yet again, the valves will be closed automatically, but if the level remains low, then the valves are automatically opened fully.
Rotork, Tel: 01225 733200; Fax: 333467.
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