Patent ID: 8268082

Claim:
A method of operating a dishwasher comprising: drawing washing fluid from within a washing chamber defined in a tub of the dishwasher into a pump housing; initially entrapping soil particles prior to directing the washing fluid to a pumping unit; pumping at least a majority of the washing fluid to upper and lower wash arms for spraying onto kitchenware being washed in the dishwasher; diverting a portion of the washing fluid into a filter chamber through a sampling port, said filter chamber having a filtering screen, a drain passage and a positive pressure valve for sealing the drain passage; sealing the drain passage by forcing the positive pressure valve closed during a washing operation to cause washing fluid to flow through the filtering screen back into the washing chamber while soil in the portion of the washing fluid is trapped in the filter chamber; ceasing a recirculation operation of the pump unit; and unsealing the drain passage by allowing the positive pressure valve to open to cause washing fluid and soil particles to flow downward out of the filter chamber.