A Novel Technique of Flow Measurement Using Pipe Line Pressure Head as a Measuring Parameter

Abstract

An obstruction meter widely used to measure flow rate of a fluid through a pipe line works on the principle of Bernoulli's equation, where the pressure difference between two sides of the obstruction is taken as a measure of flow rate. Thus the pipe line may suffer from a loss of static pressure and maximum flowing capacity cannot be utilized. In the present paper a novel technique of flow measurement is proposed in order to avoid this difficulty of obstruction meter. In this technique, no obstruction is used in the pipe line and the decrease in pipe line pressure head due to flow is taken as measure of flow. The effect of static pressure head in the pipe line is cancelled out by using to specially design identical bourdon gauges where the movement of the free tip of the bourdon tubes due to pressure is sensed by identical inductive pick up coils. One of the special gauges senses the static pressure at the source under no flow condition and the other pressure gauge senses the pipe line pressure at a given flow rate of the fluid. The free arm of aU-shaped ferromagnetic wire attached with the free tip of each bourdon tube acts as a moveable core inside and inductive pick up coil fixed with the base plate of the bourdon tube. Thus the self inductance of each pick up coil changes the change of pressure in the bourdon tube. Hence the difference between the inductances the two coils measures the change of pipe line pressure due to flow only. In the present paper a modified op-amps based differential inductance measuring circuits is designed whose output varies with the variation of flow rate. This circuit acts as proposed flow transducer. Its principle of operation is describe in the paper the performance of a prototype unit tested experiment mentally is reported in the paper in terms of static characteristics. The characteristics are found to follow the mathematical relation derived in the paper with very good repeatability.