A Venturi tube is a reliable and easily-managed and maintained instrument that can measure a wide range of clean liquids and gases. The main advantage of a Venturi tube over other differential pressure flow measuring instruments is the higher pressure recovery and the lower upstream and downstream straight pipe length requirements. The Venturi tube consists of a gradually decreasing nozzle, through which the fluid in a pipe is accelerated, followed by a gradually increasing diffuser section. The diffuser section allows the fluid to nearly regain its original pressure.