Abstract: A disposable pump of plastics material for dispensing small metered amounts of liquid from a single opening container to which it has been attached and which can be closed thereby, comprises a one piece housing and a cylindrical piston; the housing has gas inlet means for allowing gas to enter the container if any subatmospheric pressure should occur therein. A control unit for operating this pump comprises a programme for imparting a certain succession of rotative and sliding movements to the piston of said pump.

Abstract: The invention relates to an apparatus for dosing a liquid product into water, particularly for dosing a liquid detergent product into the water stream fed to domestic washing machines. The apparatus is driven by the water pressure and therefore consists of two hydraulic pressure chambers into which the water is alternately directed. In these chambers two rigidly connected pistons are moved. The pistons are connected to the housing by membrane seals. On one side of the apparatus a pumping part with a pumping chamber is located, into which one of the pistons can move. The pumping chamber is provided with a non-return valve for unidirectionally controlling the flow of the liquid product from a reservoir and with another non-return valve for unidirectionally feeding the liquid product into the water stream in the common outlet pipe. The pistons are connected to an electrically controlled valve assembly for alternatively directing the water stream to one of the two hydraulic pressure chambers.