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Wastewater · sludge

Continuous flow on a sludge line that no transit-time meter could read

The problem

A treatment plant needed continuous flow on a return activated sludge line into its SCADA. The fluid was exactly what defeats a transit-time meter — thick with suspended solids — and a wetted meter on abrasive sludge is a consumable with a replacement schedule attached.

The approach

Fixed clamp-on Doppler measurement with the Compu-Flow C6 Fixed. Doppler works by reflecting off the solids that make transit-time fail, so the very property that ruled out other ultrasonic options is the one this instrument requires. 4–20 mA into the control system, transducer on the outside of the pipe, nothing in the abrasive flow to wear.

What mattered in the detail

We confirmed the line stayed dirty year-round. Doppler goes dark on clean fluid, so a line that clears seasonally is a real design risk. This one carried solids continuously, which made Doppler the correct and durable choice.

The lesson

On sludge, the fluid property that eliminates most instruments is the one Doppler needs. The question to answer before buying is not “is it dirty?” but “is it dirty all year?”

Have a line like this one?

Send us the pipe and the fluid and we will tell you what will actually work.

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