Hydraulic piston diaphragm pumps are particularly suitable for feeding a filter press as they adapt optimally to the operating conditions specified by the filter press. The special requirements on the feed pump result from the functionality of the filter press. During feeding, the respective suspension slowly deposits on the filter cloths – resulting in the filter cake. As the flow rate increases, the conveying pressure in the feed pump then increases. Lowering the conveying rate regulates the pressure in the feed pump and thus prevents consequential damage.

Equipped with an analogue pressure sensor and a frequency converter, the initial flow rate, inflexion point and minimum flow rate can be easily set and – more importantly – varied as required. The analogue signal of the pressure sensor is transmitted directly to the frequency converter. A separate control is thus not necessary. This variant of the filter press control for the feed pump is energy-saving on the one hand. And, on the other hand, this control allows individual adjustment, especially for changing sludge, in order to achieve optimum filtration results. This is because the filtration properties of a suspension, i.e. of the medium to be filtered, cannot always be improved, e.g. by appropriate conditioning with flocculation aids. This leaves only the filter cloths and the feed pump as optimisation options.