| 摘要 |
The invention relates to a dosing pump unit for mixing a liquid reducing agent with an exhaust gas flow by means of a dosing pump ( 2 ) which is connected, on the input side thereof, to a connection connectable to a reducing agent tank ( 4 ) and, on the output side thereof, to a pressure pipe ( 16 ) and a pipe ( 10 ) for returning flow back to said reducing agent tank ( 4 ), wherein a non-return valve ( 20 ) which is prestressed against a hydraulic pressure produced by the dosing pump ( 2 ) is arranged in the pressure line ( 16 ), the return pipe ( 10 ) is connected to the pressure pipe ( 16 ) upstream of the non-return valve ( 20 ) in the reducing agent flow direction and a first stop valve ( 12 ) for selectively closing the return pipe ( 10 ) is placed therein.
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