80 GHz Radar Level Measurement in Wastewater Treatment

Application guide by Arvin, METRAVON Instruments — reviewed September 2026

An 80 GHz radar can be a strong non-contact option for wet wells, lift stations, sludge tanks and open channels. It should not, however, be selected from frequency alone. Foam, condensation, narrow chambers, inlet turbulence and the required pump or alarm function must be reviewed as one measurement system.

Define the measurement duty

Wet well: pump start/stop, alternation and overflow prevention.
Sludge tank: continuous trend and capacity protection under changing surface conditions.
Chemical tank: level control with verified wetted materials and hazardous-area suitability.
Open channel: stable level at a defined reference point for a flow calculation.

Set the range, response time, accuracy and failure state for each duty. A critical high-high trip may require an independent point-level switch rather than relying solely on the continuous transmitter.

Why 80 GHz is often considered

The relatively narrow beam can help avoid walls, ladders, cables and pipework in compact wells. Small antennas can fit limited process connections. These are useful design features, not a guarantee. Nozzle echoes, weak reflection, foam and condensation still need to be checked on the actual model.

Foam, condensation and turbulence

Dense foam can attenuate the return or become the apparent surface. Condensation may form on a cooler lens above warm wastewater. Turbulence near an inlet or pump vortex produces a rapidly moving surface. Inspect the echo curve during the worst operating condition and establish whether the process requires the foam surface or the liquid below it.

Mounting position

Mount the antenna above a representative, unobstructed surface and away from the inlet stream. Check the beam path to the lowest level. In a narrow wet well, use a section drawing to confirm the clearance from walls, ladders and cables before drilling. Keep the nozzle within the manufacturer's limits and provide drainage so water cannot remain on the lens.

Materials and site classification

Wastewater is not a complete chemical specification. Review the lens, seal, process connection and enclosure against gases, cleaning chemicals and possible corrosion. Confirm ingress protection, ambient temperature and hazardous-area certification for the actual location. The cable glands, barriers and installation method are part of that approval.

Pump-control integration

Choose start and stop points from wet-well volume, inflow, pump capacity and minimum run time. Apply enough deadband to prevent rapid cycling without delaying a real overflow alarm. Trend level with pump state, motor current and flow: a rising level while a pump runs can indicate blockage, excessive inflow or reduced pump performance.

Analogue and digital signals

Verify the 4–20 mA direction, loop load and fault-current behaviour. If HART or Modbus is used, document the address, units, quality status and update time. A supervisory system must mark stale data after communication loss rather than displaying the last value as live.

Commissioning and acceptance

Confirm dimensions, reference point, antenna location and material compatibility.
Record echo curves at independently known levels.
Test during peak inflow, aeration, foam and condensation conditions.
Verify pump sequences, high and low alarms and loss-of-signal handling.
Save settings and curves as a baseline for future maintenance.

Frequently asked questions

Can radar measure sludge?

It can track the upper surface when the echo is clear. Foam and gas may change which surface is detected, so site verification is essential.

Can it be mounted directly above a pump?

Avoid the vortex and strong turbulence. Select a point that represents the average level.

Is a separate high-level switch necessary?

That depends on the overflow risk and required independence. Critical protection commonly benefits from a separate device and signal path.

How should intermittent readings be diagnosed?

Compare the raw echo and instrument status with foam, condensation, inflow and pump operation before increasing damping or masking echoes.