Patent ID: 8297939

Claim:
A method of pumping an agglomerative liquid comprising: providing a diaphragm pump and pumping agglomerative liquid using the diaphragm pump, the diaphragm pump comprising a diaphragm having a peripheral portion and a movable portion, a pump frame having a diaphragm holding member, and a pump head having a clamping surface which extends along a single plane, the diaphragm being supported on one side of its peripheral portion by the pump frame and clamped on the other side of its peripheral portion by the clamping surface of the pump head, and the diaphragm and the pump head defining a pump chamber, wherein the peripheral portion of the diaphragm has an annular thickened portion in contact with the clamping surface, the thickened portion being thicker than the movable portion and projecting toward the pump head, the clamping surface has an inner peripheral portion, the inner peripheral portion being positioned radially within the thickened portion and spaced from the diaphragm, the pump head has at least one channel, the at least one channel comprising a groove within an inner peripheral wall of the pump head, the groove extending axially from the inner peripheral portion of the clamping surface, the diaphragm is reciprocally movable in opposite directions perpendicular to a diaphragm plane to increase and decrease the volume of the pump chamber so as to pump the liquid, the distance from an innermost periphery of the holding member to an innermost peripheral edge of the thickened portion, measured on the clamping surface of the pump head, is less than the distance between the innermost periphery of the holding member and an innermost peripheral edge of the clamping surface of the pump head, measured on the clamping surface in a region that does not comprise the at least one channel, and the reciprocal movement of the diaphragm is from a flat state toward the pump chamber side and from the flat state toward the side opposite to the pump chamber side.