US Patent 7703338 Steam meter

A flowmeter detects a differential pressure of steam as the steam passes through a conduit with a feature shaped to produce changes in velocity and pressure of the steam. Taps used to enable detection of the differential pressure extend from a wall of the conduit upward toward vertical (defined as parallel to the direction of gravitational force) in order to drain liquid water into the conduit from the tap. The differential pressure measured enables calculation of flow rate of the steam.