Liquid filter device

A method for emptying a liquid filter device having a filter housing in which a ring filter element is arranged, the filter housing including a filter housing cover and a filter housing pot tightly connectable to one another via a housing seal, the filter housing pot including a discharge channel, a central clean channel, and a vent channel disposed therein, the vent channel arranged in the clean channel, the ring filter element including an upper end plate, a lower end plate, a pleated star arranged between the upper end plate and the lower end plate, an axially and eccentrically protruding pin arranged on the lower end plate, a first seal arranged on the pin, a central second seal arranged on the lower end plate, and a third seal arranged on the upper end plate, the method comprising:

• providing the filter housing in an operating state where the filter housing cover is connected to the filter housing pot, the pin is disposed in the discharge channel and tightly engages the discharge channel via the first seal, the second seal is disposed tightly against an outer peripheral surface of the clean channel separating a raw side from a clean side, and the third seal is disposed tightly against an outer peripheral surface of the vent channel and separates the raw side from the clean side;
• detaching the filter housing cover from the filter housing pot;
• wherein detaching the filter housing cover from the filter housing pot includes one of:
• opening the first seal, opening the housing seal and the second seal after opening the first seal, flowing air onto the raw side via the housing seal, discharging liquid retained on the raw side until a liquid level on the raw side falls below the second seal, flowing air onto the clean side via the second seal, and discharging liquid retained on the clean side;
• and
• opening the first seal, opening the housing seal, the second seal, and the third seal after opening the first seal, flowing air simultaneously onto the raw side via the housing seal and onto the clean side via the third seal, and simultaneously discharging the liquid retained on the raw side and the liquid retained on the clean side the clean channel includes an elongated annular clean channel body having (i) an inner circumferential surface defining the clean channel and (ii) an outer circumferential surface defining the outer peripheral surface of the clean channel;
• and
• the vent channel includes an elongated annular vent channel body having (i) an inner circumferential surface defining the vent channel and (ii) an outer circumferential surface defining the outer peripheral surface of the vent channel.