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Positive Displacement (PD) Water Meters
measure flow with a nutating disk or piston. They are highly accurate over a wide range of flow, but are not intended to operate at high rates for extended periods of time. Use in residential water services and other applications where there may be frequent low-flow conditions.
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Turbine Water Meters
are better for larger volumes of water. They have a higher capacity than PD meters of the same size, and can pass reasonable amounts of sand and sediment without damage.
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Insertion Paddlewheel/Turbine Water Meters
can be installed through a simple tap or tee in 1/2" to 30" pressurized pipeline flowing completely full, with relatively clean water. Typical uses are monitoring flow in a water treatment plant and distribution system.
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Insertion Magnetic Meters
measure the voltage generated by liquid flowing through a magnetic field in a completely full pipeline. The liquid may be clear, turbid, or contain suspended solids, but must have a minimum conductivity (µS/cm) specified by the manufacturer.
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Spool-Type Magnetic Meters
operate on the same principle as insertion magnetic meters, but are permanently installed in a flanged section of pipe.
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Transit Time Meters
have two transducers that are clamped to the outside of a pipe that send ultrasonic signals between each other. They measure the difference in the propagation of sound waves in the direction of flow in comparison to sound waves against the flow.
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Doppler Meters
use a sensor mounted on the outside of the pipe—perfect to measure the flow of difficult liquids such as wastewater, chemicals and viscous liquids. They measure the frequency shift in an acoustic signal reflected off of particles or gas bubbles. Uses include measuring raw waste, secondary sludge, low flows, and bi-directional flow.
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Area Velocity Meters
measure both head (depth of liquid) and flow velocity to determine the flow rate in a pipeline that is not completely full, or in an open channel. The sensor mounts inside the pipe or at the bottom of a rectangular channel.
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Ultrasonic Open Channel Flowmeters
typically measure the depth of water flowing through a flume or over a weir. The sensor is mounted above the water surface and bounces a signal off of the surface to measure the relative depth. The water depth correlates to a specific flow rate for the specific flume or weir configuration.
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