Abstract: A vapor exhaust system including a volumeter 5 to which an air pump 7 has been coupled mechanically so that the volume of a certain amount of pumped liquid corresponds to the amount of air pumped from a fuel tank. A translatory or rotary motion provides the signal to maintain this correspondence, in which case the drive shaft 10 of the volumeter 5 is coupled to the air pump which may be executed as a gear pump. If desired, the coupling may be executed as a gear transmission 22.

Abstract: A stop valve (1) provided with an inlet opening (2) and an outlet opening (3) which both open at one side of a sealing (4), that is adjustable for height in dependence on the pressure in an upper chamber (5) at the other side of the sealing (4). The delivery of such a stop valve is enlarged and the diameter of the passage between the inlet opening and the outlet opening is made controllable by applying pressure puls means (9-1, 9-2) connected to the upper chamber (5), which pressure puls means may generate instantaneous pressure variations in the upper chamber (5). The height of the sealing (4) can be adjusted in steps and is therewith controllable by inferencing the time duration of the pressure pulses delivered by the pressure puls means in the upper chamber.