filter cake needs to be washed, there are open flow one-way washing and two-way washing, underflow one-way washing and two-way washing.

1. open-flow one-way washing is, wash liquid from the thrust plate wash liquid into the hole in turn, through the filter cloth and then through the filter cake, from the non-porous filter plate flow, when the orifice plate of the outlet nozzle is closed, the non-porous plate of the outlet nozzle is open.

2. open-flow two-way washing is, wash liquid from the top of the thrust plate on both sides of the liquid into the hole twice, that is, wash liquid from one side and then wash from the other side, wash liquid exports and imports is diagonal direction, so it's called two-way cross-washing.

3. underflow one-way flow washing is, wash liquid from the thrust plate into the hole in turn into the perforated plate, through the filter cloth and then through the filter cake, from the hole-free filter plate.

4. dark flow two-way washing liquid from the top of the Stop Plate on both sides of the two wash liquid into the hole twice, that is, wash from one side first, then wash from the other side, the washing liquid outlet is diagonal direction, therefore, it is also called underflow two-way cross-washing.