Guided Radar Level Measurement

Guided Radar Level Measurement

Guided radar (guided wave radar) level measurement is a time-of-flight technology that uses a probe to guide microwave pulses directly to the product surface. It is applied for continuous level and interface measurement in liquids and bulk solids, particularly where vessel geometry, foam, turbulence, or internal structures would challenge non-contact methods. The technology is valued for stable performance across a wide operating envelope.

The measuring principle sends high-frequency pulses down a rod, cable, or coaxial probe. At boundaries where dielectric properties change - such as vapor-to-liquid or one liquid layer to another - a portion of the pulse is reflected back. The instrument measures time-of-flight to calculate distance from the process connection to the reflecting surface; level is derived from known vessel dimensions. Because the signal is guided, surface condition is often of minor importance, and interface measurement is a common strength.

Guided radar is beneficial where repeatability and measurement security are priorities. It is often less sensitive to foam and turbulence than many other methods, and it can tolerate tank obstacles or baffles when properly installed. Additional diagnostics such as end-of-probe evaluation can improve confidence in the measurement and support safer operation during filling and emptying.

Typical applications include storage tanks and process vessels containing hydrocarbons, chemicals, and water-based solutions; separators requiring interface detection; and solids vessels where angled surfaces, outflow funnels, or moderate dust would complicate free-space radar or ultrasonic measurement. It is also commonly used in installations with narrow nozzles, internal piping, or limited headspace.

Probe selection (rod vs. rope vs. coax) should be based on vessel height, mechanical loads, agitation, and solids forces. Media dielectric behavior and expected coatings must be evaluated to ensure adequate reflection and long-term stability. Mounting location should minimize contact with filling streams and avoid severe build-up zones, while ensuring the probe remains clear of rotating equipment and internals.

Forberg Smith, an exclusive authorized representative of sales and service for Endress+Hauser.