Abstract: The invention relates to a method for operating a dosing pump, the pump being driven by an asynchronous motor, comprising a drive which converts the motor revolutions into pump strokes of a defined stroke frequency. The pump strokes are comprised of a pump suction stroke and of a pump delivery stroke. Pump strokes are continuously carried out during a dosing phase. The aim of the invention is to provide a solution concerning a dosing pump having an asynchronous motor drive, a frequency converter thereto, and a control unit which interacts therewith in which the dosing behavior is improved during the operation of dosing pumps having an asynchronous motor drive.

Abstract: This invention provides a sealing mechanism for sealing the piston-cylinder unit of a reciprocating diaphragm pump to ensure that the piston-cylinder unit is permanently and reliably sealed while being simple to assemble. The invention further provides a piston-cylinder unit which has almost no play in the micrometer (&mgr;m) range, and which is sealed by hydrodynamically sealing a slot thereof.