At a water-treatment plant the reagent — an alkaline solution for pH correction — sits in a 1 m³ plastic tank and is fed into the raw-water lin

At a water-treatment plant the reagent — an alkaline solution for pH correction — sits in a 1 m³ plastic tank and is fed into the raw-water line. By day the dosing pump holds the flow; at night the tank is drawn down almost to the bottom. A pilot valve that needs a differential will not open then: inlet pressure is gone, and the line still has to be flushed.

This is where a GSR series 37 solenoid valve is used. It is force-pilot operated and opens from 0 bar, so it shuts off the reagent on a full tank and on an empty one. The body is stainless steel 1.4581, the seat is PTFE: the alkaline solution does not attack the metal and the seal the way it does cast iron and NBR. A DN25 flange fits the existing pipe without a thread adapter, and the 24 V DC coil is wired to the same panel as the dosing pump. When the level drops below the setpoint, the valve closes and keeps air out of the reagent line.

The same point covers coagulant dosing and CIP detergent shut-off, provided the fluid is clean and viscosity is low. The series 37 datasheet says “clean and neutral”: for concentrated acid this is not a substitute for an externally controlled valve, and the seal is still chosen for concentration and temperature.

Supply of the GSR series 37 valve for a dosing station is handled by CSC-Automation LLC: 4-B Yevhena Sverstiuka St., Kyiv, phone +380 44 494 33 44, kck@kck.ua, https://kck.ua.