Plate-type pressurized filter is an improvement over hydraulically driven all-metal models. The use of reinforced polypropylene for the filter plate has many benefits. First it improves the chemical stability and resistancy to erosion; secondly, it is non-toxic, harmless to human health; in addition, it is lighter and easier to operate. Based on the mode of operation, the filters can be classified into manual models, jack-operated models, and hydraulically driven ones. Usually they correspond to small, medium, and large filters respectively.