The present invention relates to a pre-flush unit (10) for carrying out a pre-flush procedure in a breathing gas circuit (210) of a recirculating breathing protection apparatus (200), having a main body (20) with an inlet port (22) for the supply of breathing gas from a breathing gas reservoir (220) and with an outlet port (24) for the removal of breathing gas to the breathing gas circuit (210), wherein the inlet port (22) and the outlet port (24) are fluidically connected via a flow section (32) of a valve chamber (30) in the main body (20), and in the valve chamber (30) there is arranged a valve body (40) with a sealing face (42), the valve chamber (30) also containing an elastomer body (50) with a counter-sealing face (52) that separates the flow section (32) from a control section (34) in a fluid-tight manner and that consists of an elastic material which presses the counter-sealing face (52) against the sealing face (42) of the valve body (40) with a sealing force so as to seal the flow section (32), wherein moreover the main body (20) has a control port (26) for the controlled supply of breathing gas from the breathing gas reservoir (220) to the control section (34) for the purpose of pressure equalization between the flow section (32) and the control section (34).
