Modern water meters come in three different flow types. They function differently to measure how much water is flowing through a pipe, which means they are designed for different applications.
Water meters measure the volume of water used within commercial and residential buildings. There are two conventional approaches to water flow measurement– displacement and velocity. They vary in the method used to measure water volume, and the flow control and measurement devices in the water meter.
The Three Most Common Types of Water Meters:
Displacement Water Meters
Displacement water meters measure how much water occupies a space. The water flow displaces the measuring device in accordance with the volume of water in gallons or cubic feet that passes through the meter. A mutating disk or a piston controls the magnet that activates the water volume register.
These can most commonly be found in homes and small buildings. They can very accurately measure small amounts of water at low flow rates. The water pipes vary in size from 5/8 inch up to 2 inches in diameter. It is made of high-impact plastic, brass, and stainless steel. The measurement register is made up of a clear plastic bubble over the odometer-type or LCD gauge. These meters can also be installed in separate spaces of an apartment to measure individual water usage.
Velocity water meters measure the speed at which the water moves. They can be calibrated to adjust the accuracy of the measurement. These are the different types of velocity-based water meters:
These meters use velocity to measure water volume. The flow turns an impeller, which rotates at a known speed compared to the water speed. These water meters have internal strainer grids to prevent the jets from clogging with water particles. They are used for low-volume measurements.
These water meters are used for water pipe diameters up to 12 inches across. They are used for high-volume commercial sites such as large office complexes and factories, and even for sections of a town or city. Fire hydrant water meters are turbine water meters.
3. Compound Water Meters
These meters can accurately measure water usage in cases when water flow can vary from high velocity to low velocity. They have two measuring components and a valve to control the flow rate. The turbine meter handles the high flow and a multi-jet meter the lowest flow rates. The utility reader then determines the total water usage.
4. Electromagnetic and Ultrasonic Meters
A pair of electromagnets can measure water flow in or out of the system in a "mag meter" based on fluid induction principles. Ultrasonic meters send sound waves through the water to measure its speed and derive a water volume reading. They are used in large-volume applications and for fluids other than water.
As the technology improves, the acceptance of ultrasonic water metering is growing, usually these meter also come equipped with M-Bus communications which make them controllable and reliable. Watch your energy consumption by using a water submeter.