Below is a list of Vortex Flow Meter manufacturers from St. Louis, Missouri. Vortex flow meters measure the flow rate of liquids, gases and steam by measuring the differential pressure of vortexes created in a substance's flow. The construction of the meter is fairly simple: an obstruction is placed directly in the flow path, forcing liquids or gases to move around it. When the flow moves around this obstruction, or bluff body, two symmetrical vortices are created on the opposite side, changing the pressure of the flow.