Views: 50 Author: Site Editor Publish Time: 2025-07-25 Origin: Site
Tips for the Guided Wave Radar (GWR) Level Transmitter
1. Technology Principle:
Guided Wave Radar (GWR) level transmitters operate based on Time Domain Reflectometry (TDR). A low-energy electromagnetic pulse is sent along a probe (rod or cable). When the pulse encounters a material with a different dielectric constant (ε), part of the signal reflects back. The transmitter calculates the level based on the time delay between emission and return of the reflected signal.
2. Key Features & Advantages
Feature | Benefit |
Contact Measurement | Probe directly contacts the medium, suitable for liquids/solids |
Unaffected by Density/Viscosity | Performance independent of material properties (e.g., foam, vapor, dust). |
High Accuracy | Typical accuracy: ±1–3 mm (±0.04–0.12 in), ideal for custody transfer. |
No Calibration Needed | Measures time-of-flight, immune to drift. |
High Pressure/Temperature Resistance | Works in extreme conditions (-196°C to +450°C / -320°F to +842°F, up to 400 bar). |
Interface & Sludge Detection | Can distinguish between two liquids (e.g., oil/water) or detect settled solids. |
3. Probe Types & Selection Guide
Probe Type | Application | Example Media |
Single Rod | Clean liquids, low dielectric (ε > 1.4) | Diesel, chemicals |
Coaxial Probe | High viscosity/coating media | Crude oil, slurry, molten sulfur |
Flexible Cable | Solids, long-range (up to 30m/98ft) | Grain silos, powdered cement |
Twin Wire | Interface measurement | Oil/water separation tanks |
4. Typical Applications
Oil & Gas | Tank farm inventory management (API compliance); Cryogenic G level measurement. |
Chemical/Petrochemical | Aggressive acids/alkalis (probe material: PTFE/PFA-coated stainless steel). |
Power Plants | Boiler drum level monitoring (high-pressure steam). |
Food & Pharma | Hygienic probes (3A/Sanitary design) for syrup, milk. |
5. Installation Guidelines
Mounting | Top-down vertical installation (max 5° deviation). |
Avoid | Mechanical stress on probe, proximity to agitators. |
Dead Zone | 50–100 mm (2–4 in) near probe head – keep empty. |
6. Comparison with Other Technologies
Parameter | GWR | Non-Contact Radar | Ultrasonic |
Media Contact | Yes | No | No |
Foam/Vapor Effect | Minimal impact | Affected | Highly affected |
Accuracy | ±1~3 mm | ±3~10 mm | ±5~15 mm |
Pressure Limit | Up to 400 bar | Up to 100 bar | Up to 10 bar |
7. Troubleshooting Tips
False Echoes | Caused by probe buildup – use self-cleaning probes or increase dielectric threshold. |
Signal Loss | Check probe integrity (bent/corroded rods) and ensure proper grounding. |
