A water flow meter measures the amount of water flowing through a pipe. There are several working principles to choose from, depending on the application, maintenance needs, and budget. There are 5 main types of water flow meters.
Ultrasonic water flow meter
Ultrasonic water flow meters use ultrasound to measure flow. A transit-time ultrasonic meter sends one signal downstream and another upstream. Then the meter compares the travel time for both signals to find the flow velocity. And it uses this calculation to find the volumetric flow rate. Finally it can also be used to measure energy and temperature using the differences between the hot and cold.
Turbine water flow meter
The most popular and cheapest way to measure water flow, a turbine flow meter, measures the speed of the water running through a pipe with a rotating turbine or piston in it, usually in a propeller, shunt, or paddle wheel design. The flow rate of the water is proportional to the speed of the rotating blades. Sadly, these meters can be clogged in dirty or chunky water, such as waste water, which increases maintenance costs.
Vortex water flow meter
Vortex is the “swirl” that forms as a fluid moves past an object. In a vortex flow meter, a sensor tab flexes from side to side as each vortex flows past, producing a frequency directly proportional to the flow rate. Multivariate vortex meters measure up to five process variables with one connection: flow rate, mass flow, density, pressure, and temperature.
Electromagnetic water flow meter
Electromagnetic water flow meters use a magnetic field and Faraday’s law of induction to measure flow. Liquid flowing through a magnetic field creates a charge. So when the fluid flows faster, it creates more voltage, proportional to the movement of the water. The flow meter then processes the voltage into the flow rate.
Electromagnetic process flow meter
Electromagnetic flow meters are especially suited to measure process water flow since chunky liquids can clog turbine or vortex flow meters.