Four decentralized closing square-diaphragm control valves were replaced by Iris® Diaphragm Control Valves with a nominal diameter of DN 200 (8”) at the sewage treatment plant of Jena in Germany. The adaptation to the existing pipeline was carried out with special flanges.
The use of Iris® diaphragm control valves a substantial improvement of the oxygen control accuracy could be achieved. Control accuracies of oxygen set points of ± 0.1 mg O2 are now possible.
The compressor pressure could also be reduced to a minimum, by precise adjustment and utilization of the Iris® valve operating parameters. And the blower pressure could be reduced by 35 mbar with an optimum opening degree of the Iris® valve aperture from 70 to 95% by using of a sliding pressure control.