Abstract: An assembly including a valve unit, a suck-back unit and a valve body is proposed, the valve body including a first channel portion which leads into a first chamber having a valve seat; the valve body including a second channel portion which connects the first chamber to a second chamber; the valve body including a third channel portion which leads away from the second chamber; the valve unit including a first actuator; the first actuator closing a connection between the first channel portion and the second channel portion when the first actuator is pressed against the valve seat; and the suck-back unit including a second actuator, the second actuator, when retracted inside the second chamber, sucking back a fluid in the third channel portion towards the second chamber if the connection between the first channel portion and the second channel portion is closed.