Radar Level Measurement: Industrial Application Guide

Radar has become the preferred technology for level measurement in process industries. Its main advantage is immunity to changes in temperature, pressure, vapors and medium density. This guide explains the two main variants and how to apply them correctly.

1. Non-contact radar vs. Guided Wave Radar (GWR)

Non-contact radar emits a microwave pulse from an antenna mounted at the top of the tank. The signal bounces off the product surface and returns to the sensor. There is no physical contact with the media, making it ideal for processes with high temperature, foam, strong agitation or products that must not be contaminated.

Guided Wave Radar (GWR) sends the signal along a metal probe that descends to the bottom of the tank. The microwave energy propagates along the guide and reflects when it encounters a change in dielectric constant (the product surface). It is more accurate in small tanks and in liquid-liquid interface measurement.

2. Frequency selection

The radar frequency determines beam behavior:

• High frequency (78-80 GHz): Narrower beam, ideal for tanks with internal obstacles, small nozzles and installations with sparse internals. Better resolution.
• Low frequency (6-10 GHz): Wider beam, better for large tanks with rough surfaces or low-dielectric-constant products. Better penetration through foam and dust.

3. Proper installation

Installation is one of the most critical factors for radar performance. For non-contact radar:

• The antenna must extend above the mounting nozzle or use an extension pipe.
• Avoid aiming the beam directly at walls, agitators or internal piping.
• Maintain minimum wall distance (at least 200 mm for high frequency).
• Avoid direct fill zones where the incoming stream can generate spurious echoes.

For GWR, the probe must remain straight, unbent, and away from the tank wall. If measuring liquid level only (not interface), the probe can end before the bottom. If interface measurement is required, the probe must reach the bottom.

4. Tank parameters and configuration

Parameters to configure include:

• Total tank height: Distance from sensor reference to the bottom.
• Blind zone: Region near the antenna where the radar cannot measure.
• Fill curve: Relationship between echo signal and actual product level.
• Product dielectric constant: Affects echo strength. Products with low constant (<4) require GWR.

5. False echo diagnosis

One of the most important tasks during commissioning is verifying the echo map. False echoes can come from:

• Tank internal structures (beams, coils, agitators)
• Mounting nozzles or reducers at the inlet
• Turbulent filling or internal cascades
• Product buildup on the probe or antenna

Most radar transmitters allow false echo suppression by configuring dead zones where the instrument ignores the signal. This is done via the "false echo suppression" or "tank mapping" function available in the configuration menus.

6. Typical industry applications

• Mining: Level measurement in mineral silos, hoppers and fill streams. High-frequency radar handles dust and multiple echoes well.
• Oil & Gas: Storage tanks, oil/water separators (GWR for interface), process vessels.
• Chemical: Tanks with corrosive products, acids, solvents. Non-contact radar avoids media contact.
• Food & Beverage: Hygienic measurement in CIP tanks, dry material silos.
• Water & Wastewater: Level in open channels, decantation tanks, sumps.

Conclusion

Radar technology offers one of the most reliable solutions for industrial level measurement. The key is to correctly choose between non-contact radar and GWR based on process conditions, with proper installation and configuration. A well-installed and configured radar requires minimal maintenance and provides accurate measurements for years.

MARPATECH SAC represents in Peru, Argentina and Colombia leading level instrumentation manufacturers including SOR, Monitor Tech and DUK, providing complete technical support for selection and installation of radar level measurement systems.