Method and apparatus for determining multiphase flow by measuring pressure

A multiphase flow metering method is described which comprises the steps of determining two pressure values P 1 and P 2 at two different points (A and B) within a sampling chamber (4) and the value of the internal pressure P 0 of the main chamber (8). From these values and the known gas and /or liquid densities, the level of the interface (h l ) between the liquid and gas phases may be determined, as can the flow rate of the multiphase, that of liquid phase and that of the gaseous phase. Apparatus capable of performing said method is also described.