Measures flow by inferring the flow through a pipe from some physical property of the flow stream, such as, differential pressure; orifice plates; flow nozzles; venturi tubes or variable area rotameters. A differential pressure drop device creates a pressure drop an obstruction in the flow.
Flow is measured in terms of dynamic force acting on a target (solid disk) in the flow stream. Four strain gages connected in a bridge circuit configuration mounted outside the flow stream translate force into an electrical output. This output is proportional to flow rate squared.
- No frictional moving parts to wear out
- Fast response time
- Can be used with liquids, gases, steam, and cryogenics