Differential pressure metering device

A metering device for transferring, from an upstream space towards a downstream space, a predetermined volume of a fluid in response to a rise in pressure of the fluid in the upstream space, the metering device comprising at least a hollow body, a valve, and a sealing seat defined over a hollow or substantially annular member and surrounding a fluid passage disposed between the upstream space and the downstream space, the hollow body delimiting at least partially a chamber provided with an inlet and an outlet, the valve being movable with respect to the hollow body between a rest position, towards which the valve is biased by a return force, at least partially including an elastic return force, and an end position, which is spaced from the rest position and towards which the valve is selectively biased by the fluid flowing from the upstream space towards the downstream space, and in which the valve rests on the sealing seat, the upstream space extending at least outside the chamber on an inlet side, the downstream space extending at least outside the device and the chamber on an outlet side, the valve isolating one from the other the upstream space and the downstream space in its end position and only in this position, and the outlet of the chamber communicating with the upstream space for any position of the valve other than its end position, wherein the valve includes a diaphragm movable in translation with respect to the hollow body and at least one elastic tab attaching the valve to the hollow or substantially annular member, wherein the hollow or substantially annular member, the valve, and each elastic tab are integrally made from an elastic material, wherein the return force is exerted by each elastic tab, and wherein, once the rise in pressure is released, air enters the chamber via the outlet of the chamber.