Apparatus and Method for Dosage of Additives While Collecting a Liquid

Apparatus for suction of a liquid from a collecting location, which apparatus includes:

• a suction conduit (4) having an inlet end (5) and being connected to a sub pressure source (1) for creating a sub pressure in the suction conduit (4), and
• a dosage unit (12) for continuously during suction dosing additives to the liquid in a quantity that is proportional to the quantity of sucked liquid, which dosage unit includes:
• a conduit for additives (13) being connectable to a storage of additives (14) and having an outlet end (15) for feeding the additive to the liquid, and
• a regulating device (38) for regulating the flow of additives from the outlet end (15) of the conduit for additives (13) in dependence of the sub pressure in the suction conduit (4), the outlet end (15) of the conduit for additives (13) being arranged close and in a fixed position with respect to the inlet end (5), such that the additive is fed to the liquid at the collecting location (16) simultaneously as the liquid is being sucked, the additive being sucked through the inlet end (5) of the suction conduit (4) together with the liquid,
• characterised in that the regulating device (38) includes a pressure element (35) controlled by the sub pressure in the suction conduit, which pressure element applies an increasing overpressure to the additive in the storage (14) of additives, the increase of the overpressure relating to an increase of the sub pressure in the suction conduit (4), for to increase the flow of additives from the outlet end (15) of the conduit for additives (13) in proportion to the increase of the sub pressure in the suction conduit.