A Paddlewheel flowmeter is a flowmeter with three primary components - a paddle wheel sensor, a pipe fitting, and a controller. Paddlewheel sensors detect flow rate by rotating a freely-rotating wheel, or impeller, positioned perpendicular to the flow. The paddlewheel rotates when the device is inserted into the flowing medium, generating an electrical signal that's proportional to the flow rate.
The programmable Paddlewheel Flowmeter is made of polypropylene and is pre-wired for a dry contact signal. They are often used as flow indicators for cooling towers, mixing systems, and cleaning systems. The flow rate displayed by a paddlewheel flowmeter depends on the amount of time it takes to rotate the paddle, divided by the pipe diameter. The microprocessor averaging process minimizes turbulence in the water and allows the user to see both the flow rate and the totalized flow.
The most common types of fluids that may be used with a paddlewheel flowmeter are neutral and aggressive liquids. The flow of high-viscosity fluids tends to produce a laminar flow profile, where the center of the fluid moves faster than the outer edges. To obtain a more turbulent flow profile, fluid velocity must be uniform across the pipe diameter. To achieve this, the Reynolds Number of the fluid is higher than 4000, which is the combined effect of flow velocity, density, and viscosity.
The most commonly used paddlewheel flowmeter is the type 8012, which is suitable for applications with liquids at elevated temperatures. It can handle fluid temperatures up to 160 degC and is highly accurate.