Installing Radar Level Meters on Agitated Tanks

An agitator does not automatically prevent radar level measurement, but it changes what the instrument sees. The surface may slope or form a vortex, blades create moving reflections, and splashing or foam can weaken the product echo. Reliable installation starts with vessel geometry and operating states, not with software suppression after the radar has been mounted.

Map the moving geometry

Obtain a plan and elevation showing shaft, blade diameter, baffles, coils, inlet streams and level range. Calculate where each moving part enters the antenna beam. A blade that is clear when stopped may intersect the beam during operation or at a different liquid level.

Record agitator speed, direction, operating sequence and whether the vessel is measured while mixing, filling, draining or settling. The most difficult state should drive the mounting review.

Choose a representative surface

Avoid the vortex centre because it may sit below the average liquid level and become unstable with speed. The vessel wall is not automatically better: surface climbing, baffles and wall buildup can distort that region. Select a clear point that represents the control objective across the usable range.

If batch volume is calculated from level, quantify the error caused by the dynamic surface. A settled measurement may suit inventory reconciliation while a filtered live signal supports pump control. Document which value is used for each purpose.

Protect the beam and antenna

Position the antenna outside direct fill streams and spray zones. Check the full beam width, not only its centreline, against blades and internals. A narrow beam improves selectivity but cannot correct an antenna aimed at an unrepresentative surface.

Use a nozzle that meets the selected antenna's requirements and lets it project as specified. Condensate, sticky splash and foam residue can collect in a recessed nozzle. Provide safe inspection or cleaning access without adding a guard inside the beam.

Handle moving echoes conservatively

Compare raw echo curves with the agitator stopped and at each normal speed. Identify reflections that move with blade position and distinguish them from the product surface. Use false-echo mapping only for proven fixed targets; broadly suppressing a region can hide the real level.

Set response damping to the process need. Heavy filtering can create a calm display while delaying a genuine rapid rise. Verify rate-of-change limits, lost-echo behaviour and held-value indication in the control system.

Test foam, splashing and alarms

Clarify whether operators need the foam top or the liquid below it. Foam properties can change by recipe, temperature and agitation. Test representative batches rather than assuming the clean-water commissioning result applies to production.

Verify low and high alarms during relevant operating states using an independent reference. Include agitator permissives, pump trips and any settling delay in the functional test. Retain echo curves and observed conditions.

Worked reactor example

A reactor radar initially points near the shaft and intermittently selects a blade echo. Drawings show a clear region between a baffle and the fill stream. The connection is moved, and the antenna is projected beyond the narrow nozzle instead of masking the central measurement zone.

Commissioning records curves with the mixer stopped, at low speed and at full speed. The signal remains stable, while the high-level trip is tested with the configured damping included in the response time.

Engineering checklist

• Plot the complete antenna beam against moving internals.
• Avoid vortex centre, fill streams and spray zones.
• Define the representative surface and measurement duty.
• Compare echo curves at every normal agitator speed.
• Use mapping only for confirmed fixed echoes.
• Test alarms with real damping and process timing.

Frequently asked questions

Should radar be installed at the tank centre?

Usually not when a central agitator or vortex occupies that region; use the clearest representative location.

Can damping remove blade interference?

It may smooth the output but does not correct wrong echo selection and can delay alarms.

Must the agitator stop for measurement?

Not necessarily. The application should be commissioned at each required operating speed and duty.

Related measurement solutions

80 GHz radar level meters · 26 GHz radar level meters