The operating principle of a pressure belt filter works, in contrast to the described vacuum filter systems, with an overpressure on the dirt side. These plants are often used for the purification of contaminated cooling lubricants. Due to high feasible throughput capacities of up to 10 m³/min they are especially suited as central units. Because of the good and clocked operation of the filter nonwoven due to high differential pressures, separation efficiencies in the single-digit µm-range are achieved. At the same time one obtains a very dry filter cake.