The measuring system comprises a sharp edged fixed orifice ring, and a tapered float.
When the fluid flows vertically upwards, the float rises until a point of equilibrium is reached where
the weight of the float is balanced by the buoyancy force 'A'.
This results in an annulus 'S' the area of which is directly proportional to the flowrate.
The vertical movement of the float is transmitted to an external indicator through a magnetic coupling
system such that glands and seals are avoided.