They may measure flows in open channels, tubes, partially filled pipes, streams, rivers, wastewater, industrial process waters, and more. Many water flow meters are designed for metering pump pacing or water treatment control but they have other applications as well.
Water flow meters can aid in rain water runoff studies, sewer flow measurements, and measuring flows in bodies of water. Most water flow meters are made of three parts: the primary device, transducer, and transmitter. These three parts are combined so that the flow meter is one complete device conveniently enclosed in one assembly. They are usually made out of metal such as stainless steel or they may be plastic.
Water flow meters are useful in a variety of fields. In plumbing, these flow meters are used to measure the amount of water running through a tube or pipe for efficiency purposes. Water flow meters are also used in many industrial purposes for flow measurements to help companies determine profit gain or loss. Industrial water flow meters are also available for larger-scale applications. Other industries that benefit from the use of flow meters include automotive, petroleum and gas, utility services, HVAC, food processing, and raw materials.
Many water flow meters measure water velocity through the use of a probe that contains a positive displacement sensor that takes a measurement and puts it on a readout display. Water flow meters utilize velocity averaging for the most accurate flow measurements. They also provide quick and efficient information for simple flow monitoring. Water flow meters are also convenient as they are lightweight, waterproof, and reliable.
Some water flow meters measure the volume of water while other flow meters measure the speed or mass. For the most part, flow meters are used to infer mass flow through calculations that flow meters and flow monitor instruments make after taking various flow measurements, such as absolute pressure, differential pressure, viscosity, and temperature.
Another kind of flow meter includes thermal mass flow meters which have two sensors to take temperature measurements before calculating how much heat loss occurs in the flowing liquid. Other flow meters employ the Doppler Effect which is when ultrasonic waves reflect back from particles or bubbles in the liquid to determine the rate. Still other kinds of flow meters are Coriolis flow meters that use the Coriolis Effect where a force is applied to the tube to make the fluid or gas inside rotate or flow indicators which have a viewing window.