Instrumentation · 8 min read · Updated November 2026
80 GHz Radar vs Ultrasonic Level: Where Each Wins in 2026
Compact 80 GHz radar sensors now cost little more than a good ultrasonic transmitter, which has changed the default for tank level. Ultrasonic still wins in some places. A side-by-side from the applications we commission most — chemical day tanks, water basins, silos and small vessels — with the failure modes of each.
Ten years ago the choice for a chemical storage tank was easy: ultrasonic for the budget, 26 GHz radar if vapour or foam made ultrasonic unreliable, and a process radar from Endress+Hauser or VEGA for anything difficult. Today compact 80 GHz radars — VEGAPULS C 21/C 23, Endress+Hauser Micropilot FMR10/FMR20, Siemens LR110/LR120, Flowline EchoPulse LR30, KROHNE OPTIWAVE 1010 — sit at the price of a mid-range ultrasonic, and the process-grade 80 GHz units such as the VEGAPULS 64 handle what used to need guided-wave radar. Ultrasonic has not disappeared; it has become a specialist tool. Here is how we decide.
How they measure, and why it matters
Ultrasonic transmits a sound pulse through the gas phase and times the echo. Sound speed depends on the gas composition, temperature and pressure — about 0.17 % per °C in air — so the sensor compensates with an internal temperature sensor and assumes air. Dense vapour, foam (which absorbs sound), vacuum (no medium) and strong temperature gradients all corrupt the measurement. Radar transmits an electromagnetic pulse (or FMCW sweep) whose speed is essentially constant regardless of gas composition, temperature and pressure; the echo depends on the dielectric constant of the liquid (anything above ~1.5 reflects enough) and the beam geometry. At 80 GHz the antenna can be tiny and the beam narrow (3–8°), so the sensor sees past agitators, ladders and build-up on walls, and fits into a 3/4-inch nozzle.
Side-by-side
| Criterion | Ultrasonic | 80 GHz radar (compact) | 80 GHz radar (process) |
|---|---|---|---|
| Vapour, fumes, temperature swings | Weak — drift and lost echo | Unaffected | Unaffected |
| Foam | Poor — absorbs sound | Good for light foam; dense foam attenuates | Good; echo-curve tools and high dynamic range |
| Vacuum / pressure | Not usable in vacuum; limited pressure | −1 to 3 bar typical | −1 to 25 bar and more |
| Dead band | 20–50 cm | ~5 cm (some 0 cm with near-field processing) | Near zero |
| Small nozzles / internal obstacles | Wide beam, needs clear path | Narrow beam, 3/4–1.5 in mounting | Narrow beam, flush antennas |
| Dusty solids | Weak | Good (lens antenna versions) | Excellent |
| Condensation on sensor | Moderate issue | Minor with encapsulated antenna | Minor; self-cleaning lens options |
| Price (2026) | Low | Low to medium | Medium to high |
| Approvals | IP68, some Ex | IP66/68, Ex ia versions, SIL on some | Full Ex, SIL2/3, WHG, hygienic |
Where ultrasonic still wins
- Open channels and weirs. Flow measurement in open channels by level over a weir or flume is classic ultrasonic territory: clean air, no foam, non-contact, and the sensor is cheap enough to install several. Radar works too, but ultrasonic flow controllers (with built-in Manning/Parshall tables) are mature and inexpensive.
- Clear-liquid day tanks and sumps indoors with stable temperature and no fuming chemicals. An EchoPod DL24 with its four switch outputs replaces a transmitter and two float switches for the price of one device.
- Very low dielectric liquids (some solvents and oils, εr below ~1.6) where radar returns a weak echo; sound does not care about dielectric constant.
- Transparent-to-radar vessels. A radar mounted above a plastic tank may see through the tank bottom to the floor; ultrasonic sees the liquid surface. Easily handled by radar parameterisation, but a trap for the unwary.
Where 80 GHz radar is the answer
- Sodium hypochlorite, acids, caustic, ferric chloride and any tank that fumes or outgasses — the EchoPulse LR15 class exists for exactly this.
- Outdoor tanks with day/night temperature swings and condensation.
- Tall narrow tanks, tanks with agitators or heating coils, and small vessels with 3/4–1 in nozzles.
- Silos and hoppers with dust (lens-antenna versions).
- Anything needing Ex, SIL or hygienic approvals, or an echo curve to diagnose.
- Vacuum or pressurised vessels.
Commissioning notes that save a site visit
Mount radar perpendicular to the surface, away from the fill stream and at least 200–300 mm from the wall; in plastic tanks use a mounting plate or set the false-echo suppression with the tank empty. For ultrasonic, respect the blanking distance and avoid mounting in a riser longer than the manufacturer allows — standing waves in a narrow pipe are the most common cause of erratic readings. Both technologies: set the empty and full distances from a tank drawing, not by filling the tank, and record the parameters in the asset file so a replacement can be configured on the bench. Most of the compact radars and the EchoPod series support configuration by Bluetooth or USB, which we do before shipment when you send the tank dimensions.
Three applications from our commissioning log
Hypochlorite tank, water treatment plant. An ultrasonic transmitter had been replaced twice in three years; readings drifted in the afternoon heat and dropped out when the tank was filled (chlorine vapour). A compact 80 GHz radar in the same 2 in bung, parameterised with the tank drawing, has run two years without a service call. Cost difference at purchase: about 15 %.
Open channel after a sedimentation basin. Ultrasonic flow transmitter over a Parshall flume, mounted on a bracket 400 mm above maximum level, with the flume tables in the transmitter. Clean air, no foam, stable temperature under a roof; nothing to gain from radar, and the ultrasonic unit cost half as much. Still ultrasonic after eight years.
Reactor with agitator and heating jacket, chemical plant. A 26 GHz horn radar had struggled with the agitator blades and foam during batch addition. An 80 GHz process radar with a 3° beam, mounted on a DN50 nozzle away from the shaft, with the echo curve used to map the blades as false echoes, reads through the foam and is SIL2-rated for the high-level trip. This is the case where the premium process radar earns its price; a compact radar would have worked for level but not for the safety function.
Specification checklist
- Tank material, height, nozzle size and position, distance to wall and to any internals.
- Medium: dielectric constant class (water-based, solvent, oil), foam, vapour, build-up tendency.
- Process temperature and pressure range, including CIP or steam-out.
- Required accuracy and dead band; whether the first 5–20 cm at the top matter.
- Output and configuration: 4–20 mA, IO-Link, HART, Bluetooth; who will configure it and with what tool.
- Approvals: Ex zone, SIL for overfill, hygienic, drinking-water, IP69K for washdown.
- Mounting accessories: flanges, mounting plates for plastic tanks, sunshades outdoors.
Need engineering help with this?
Our engineers apply this to real projects every week — selection, specification, commissioning. Send your question or a part number.
Quick answers
Is 80 GHz radar affected by the tank being plastic?
The radar may see through plastic walls or the bottom and lock onto the floor or external objects. It is handled by mounting on a plate, aiming correctly and running false-echo suppression; once set up, plastic tanks are routine.
Can I replace an ultrasonic transmitter with a radar one-for-one?
Usually yes: most compact radars use the same 2 in / G2 thread, 24 V DC two-wire 4–20 mA loop and similar ranges. Re-parameterise empty/full distances and check the dead band, which is shorter on radar.
Which do you recommend for a chemical dosing skid?
Compact 80 GHz radar for the chemical tanks (fumes, foam from dosing), ultrasonic or hydrostatic for the water tank, and a vibrating-fork switch as independent high-level protection on anything that can overflow.