Abstract: A valve arrangement for venting conduits in pumping systems having several pumping units for delivering a gas or vapor generating liquid includes a double-seat valve in which the valving element moves between two extreme closing positions and an intermediate position in which the venting conduit is momentarily open; as the venting conduit is connected at one end with the gas collecting zone in one pumping unit and at the opposite end with the liquid discharging zone below the delivery valve so that the double seat valve is automatically controlled by the pressure difference resulting due to different operational phases of the pumping system.