Vortex flowmeter measures the flow by sensing the vortices in the flow according to “Von Karman Vortex Street Theory”. When put a shedder in the path of flow, vortices are alternately shed on each side. A pair of piezo sensors are located after the shedder bar, to count the quantity of the vortexes, therefore, to know the flow that pass through. The ratio between quantity of vortices in a certain period of time and the volume of the flow pass by is called coefficient of the instrument(K factor). eg K factor = 1.5, means 1pulse=1/1.5liter

thermal mass flowmeter is to measurement of fluid flow in closed conduits. The flow meter with two sensors mounted on a probe, inserted through the process conduit wall, into the gas stream. An amount of heating power P is applied to one of the sensors, causing its temeprature to raise to a measured value T2, the other sensor measures the gas temperature T1. The gas mass flowrate can be determined from the temperature difference between the heated sensor and the gas(△T=T2-T1), and the amount of heating power P applied.

Determine the fluid flow by measures the differential pressure with the velocity in the oncoming flow and back flow of the sensor. The performance of a DP flow meter depends on many aspects: probe design, Signal processing algorithm, differential pressure value detection, etc.