Level measurement is one of the most common process variables in industry, and the three most common non-contact/contact technologies are radar, guided wave radar and ultrasonic. Each has a clear sweet spot. This guide uses the VEGA range — the world's largest family-owned level-measurement manufacturer — to show when to pick which.
At a Glance: The Short Answer
Choose radar (VEGAPULS) for most liquids, especially with agitation, foam or vapours. Choose guided wave radar (VEGAFLEX) for interface measurement, low-dielectric media and high temperature/pressure. Choose ultrasonic (VEGASON) for simple open-tank water and wastewater where cost matters more than precision.
Technology Comparison Table
| Feature | Radar (VEGAPULS) | Guided Wave (VEGAFLEX) | Ultrasonic (VEGASON) |
|---|---|---|---|
| Principle | 80 GHz microwave, non-contact | Microwave along probe | Sound wave, non-contact |
| Accuracy | ±2 mm | ±2 mm | ±5–10 mm |
| Foam / vapour | Very tolerant | Tolerant | Sensitive (attenuation) |
| Interface (oil/water) | No | Yes | No |
| High temp / pressure | Yes (VEGAPULS 69) | Yes (VEGAFLEX 86) | Limited |
| Bulk solids | Yes | Yes | Yes |
| Cost | Mid | Mid | Lowest |
When to Choose Radar (VEGAPULS)
The VEGAPULS family uses 80 GHz radar for non-contact, maintenance-free measurement. Choose radar when:
- VEGAPULS 64 — the general-purpose radar for liquids, with ±2 mm accuracy and an encapsulated antenna.
- VEGAPULS 66 — for aggressive or corrosive liquids, with a PEEK encapsulated antenna for high chemical resistance.
- VEGAPULS 69 — for high-temperature, high-pressure applications such as LNG and chemical reactors.
Radar is the default choice for modern liquid measurement because it is immune to vapour, foam and changing process conditions that defeat ultrasonic sensors.
When to Choose Guided Wave Radar (VEGAFLEX)
Guided wave radar sends the microwave down a rod or cable probe, making it ideal for difficult media:
- VEGAFLEX 81 — for level and interface measurement (e.g. oil over water) with a rod or cable probe.
- VEGAFLEX 86 — the high-temperature coax version for steam boilers and hot-oil systems.
Choose guided wave radar when you need to measure an interface between two liquids, or when the medium has a very low dielectric constant that free-space radar would miss.
When to Choose Ultrasonic (VEGASON)
The VEGASON 62 (ultrasonic) remains a valid, low-cost option for simple applications — open tanks, sumps and water/wastewater channels — where vapour and foam are not a problem and ±10 mm accuracy is acceptable.
Complementary Instruments
For point-level switching and pressure-based level, VEGA also offers:
- VEGACAP 64 — capacitive point-level switch for high/low alarm.
- VEGABAR 82 — pressure transmitter for level via hydrostatic pressure, ±0.1% accuracy.
Decision Guide
- Liquid, agitated/foamy/vapour? → Radar (VEGAPULS 64).
- Aggressive chemical? → VEGAPULS 66 (PEEK antenna).
- High temp/pressure (LNG, reactor)? → VEGAPULS 69 or VEGAFLEX 86.
- Oil/water interface? → VEGAFLEX 81.
- Simple open-tank water, budget-limited? → VEGASON 62.
- Point-level high/low alarm? → VEGACAP 64.
Get a Quote
Glorient supplies the complete VEGA range — VEGAPULS radar, VEGAFLEX guided wave, VEGASON ultrasonic, VEGABAR pressure and VEGACAP switches. Tell us your medium, vessel and process conditions and our engineers will recommend the right technology. Request a quotation and we will respond within 24 hours.