Traditional flow meter will beblocked and worn by high viscosity, article containing fluid in oil andchemical measurement causing failure in work or accuracy. As a new designedflow meter, rectangle flow meter has advantages of both wedge flow meter and venturiflow meter and improved in key function. Compared with other flow meters,rectangle flow meter is without moving parts, wear resistant and durably highaccurate. It is gradually applied topetrochemical, coal chemical, power industry and so on. Rectangle flow meter is a throttling element that generatesdifferential pressure signal. As other traditional differential pressure flow sensors, they are based on theprinciple of energy conversion in sealed pipes: In the case of ideal fluids,the flow in the pipe is proportional to the square root of the differentialpressure. The flow in the pipe can be calculated from the differential pressurevalue according to the Bernoulli equation.