Pumps, especially those used to convey liquid media must be protected from damage due to solid particles. Depending on the size and the type of the pump are required different fineness. The Type and quantity of the attacking particles is in turn depending of the specific application and the media. In closed systems or application without, or with just very low expected entry of dirt, a protection filter as simplex filter with comparatively small filter surface applied.
Through the suction side Installation of the filter prior to a pump, the supply pressure of the pump is dropping by rising pressure drop across the filter. The filter has thus a dynamic influence on the NPSH-value of the plant. To take this effect low a filter have to show a low drag coefficient and a large filter surface. For a uninterruptible operation a double filter installation is require, whereby the same maxim applies here with regard to the resistance coefficient for the switch valve. Especially for large flow rates, the switch-over unit is a constructional challenge regarding the filter size and the required positioning forces for the manual switching.
The valve-Duplexfilter series VS87 is in welded designed. The large filter areas allow low pressure loss by coincident long maintenance intervals. The system has closed strainers which removed upwards facilitate the operation and reduces the maintenance period. The duplex element offers a smooth handling and prevented operating errors.
Customer advantages are an uninterruptible operations due to switching option, minimal influence of facilities-NPSH and a simply operation due to smooth handling. Operating error of the switching is excluded through only one operating lever. Further advantages are a high operation safety and easy handling through closed Strainers. The system is compact designed, requires only less space and can be integrate without problems in already existing systems.