An apparatus and method is provided for determining the static gas pressure in a gas/liquid flow. The apparatus and method may be non-invasive relative to the flow to be analyzed. The apparatus and method may include swirling a multiphase flow so that the flow is separated into a gas core and a liquid outer layer, measuring flow parameters, including the liquid layer tangential velocity, the liquid holdup, and the static pressure of the flow at the wall of conduit, and determining the static gas pressure in the gas core from the measured flow parameters.