Abstract: This flow-meter comprises an enclosure separated into two chambers by a flexible and sealed diaphragm fast at its center with a rigid dome. A compression spring presses the dome, which is pierced in its center with a hole, upon a cone fast with the enclosure, and exerts a constant force upon the dome. The fluid penetrates into the flow-meter through the orifice, passes between the cone and the dome which it raises, and emerges through the orifice. A contactless displacement detector measures the displacement of the dome which is proportional to the flow rate of the fluid.