Basic knowledge and comparison of several flow meters

1. Differential pressure flowmeter (DP): It is the most common flow technology, including orifice flowmeter, V-cone flowmeter, venturi and sonic nozzle. DP flow meters can be used to measure the flow rate of most liquids, gases and vapors.The DP flow meter has no moving parts and is widely used and easy to use. However, after clogging, it will cause pressure loss and affect accuracy. The accuracy of the flow measurement depends on the accuracy of the pressure transmitter.

2. Turbine Flow Meter: The fluid rotates the rotor as it flows through the turbine flow meter. The rotational speed of the rotor is related to the velocity of the fluid. The flow rate or total amount is derived from the average flow rate of the fluid sensed by the rotor. Turbine meters accurately measure clean liquids and gases. Like PD flow meters, turbine flow meters can also create unrecoverable pressure errors and require moving parts.

3. Electromagnetic flowmeter: The electromagnetic flowmeter has a conductive fluid. When flowing through an electromagnetic field, the velocity of the fluid can be obtained by measuring the voltage. The electromagnetic flowmeter has no moving parts and is not affected by fluids. Measuring conductive liquids at full tube is highly accurate. An electromagnetic flow meter can be used to measure the flow rate of the slurry fluid.

4. Ultrasonic flowmeter: The propagation time method and the Doppler effect method are commonly used methods of ultrasonic flowmeters to measure the average velocity of a fluid. Like other speed meters, it is a meter that measures volumetric flow. It is an unobstructed flow meter and does not need to be inserted if the ultrasonic transmitter is installed outside the pipe. It is suitable for almost all liquids, including slurries, with high precision. However, the contamination of the pipe will affect the accuracy.

5. Vortex flowmeter: The vortex flowmeter is a non-streamlined vortex generator placed in the fluid. The velocity of the vortex is proportional to the velocity of the fluid to calculate the volume flow. Vortex flowmeters are suitable for measuring liquids, gases or vapors. It has no moving parts and no dirt problems. Vortex flowmeters generate noise and require a high flow rate of fluid to create a vortex.

6. Thermal Mass Flow Meter: The fluid velocity is measured by measuring an increase in the temperature of the fluid or a decrease in the thermal sensor. Thermal mass flow meters have no moving parts or holes to accurately measure gas flow.Thermal mass flow meters are one of the few technologies that measure mass flow and are one of the few techniques used to measure large-caliber gas flows.