Sample Preparation Dosing Unit

A sample preparation dosing unit for liquid dosing from a supply to a target in a sample preparation device, comprising:

• an inlet port for fluidically coupling the sample preparation dosing unit to the supply;
• an outlet port for fluidically coupling the sample preparation dosing unit to the target;
• a pump, fluidically arranged between the inlet port and the outlet port;
• an outlet flow restrictor with an outlet flow resistance, fluidically arranged between an outlet of the pump and the outlet port;
• and
• a control arrangement with a branch, a control valve and a control flow restrictor with a control flow resistance, such that
• the flow at the outlet of the pump is divided by the branch into an outlet flow through the outlet flow restrictor and into a control flow through the control flow restrictor, and the control flow downstream of the control flow restrictor is fed, in dependence of the state of the control valve either
• into the outlet port such that it merges with the outlet flow downstream of the outlet flow restrictor, or
• into a bypass conduit.