I. Characteristics of Radar Level Meters (Non-Contact)

1. Non-Contact Measurement with Excellent Safety and Hygiene

• No Medium Contact: The sensor has no physical contact with the measured medium, eliminating risks of corrosion, wear, material buildup, or contamination caused by the medium.
• Strong Hygienic Compliance: Ideal for industries with strict hygiene requirements such as food & beverage and pharmaceuticals (meeting standards like FDA and 3-A), avoiding concerns about sensor material shedding or cross-contamination of media.

2. Flexible Installation and Low Maintenance Costs

• Easy Installation: Typically mounted above the top of tanks, requiring no insertion into the medium and causing no interference with internal tank structures. Particularly suitable for retrofitting existing tanks or large-scale storage tanks (no need for drilling or tank modifications).
• Low Maintenance Needs: No moving parts and no contact with the medium reduce maintenance work caused by buildup, blockages, or wear, extending service life.

3. Adaptable to Multiple Media but Sensitive to Environmental Interference

• Wide Medium Compatibility: Capable of measuring liquids, solid particles (e.g., plastic pellets, grains), and slurries. Especially suitable for high-viscosity media (e.g., honey, resin), highly corrosive substances (e.g., acid/alkaline solutions), or volatile media.
• Environmental Sensitivity: Microwave signals are susceptible to environmental factors such as vapor, dust, foam, and mist during propagation, which may weaken or distort reflected signals. High-frequency designs (e.g., 26GHz, 80GHz), specialized antennas (e.g., horn antennas, parabolic antennas), or signal filtering technologies are used to enhance anti-interference capabilities.

4. Wide Measurement Range, Accuracy Influenced by Dielectric Constant

• Large Measurement Range: Conventional ranges reach 0.1m–100m, with some models covering ultra-large storage tanks or open vessels.
• Dependence on Dielectric Constant: Higher dielectric constant (εᵣ) of the medium results in stronger reflected signals (e.g., water with εᵣ≈80 has strong reflections). Low dielectric constant media (e.g., gasoline with εᵣ≈2, liquefied petroleum gas with εᵣ≈1.5) produce weak reflections, potentially reducing measurement accuracy (improved by high-frequency radar or enhanced antennas).

Limitations

• Difficult to measure media with very low dielectric constants (εᵣ<1.5) and prone to interference from false echoes (e.g., reflections from tank walls or agitators).
• In harsh conditions with heavy dust, high vapor, or thick foam, additional dust/fog-resistant antennas or purging devices are required; otherwise, accuracy may decrease.

II. Characteristics of Guided Wave Radar Level Meters

1. Contact Measurement with Strong Anti-Interference Capability

• Directional Signal Propagation: Microwaves travel along the guided probe, concentrating energy and minimizing interference from environmental factors such as vapor, dust, foam, or turbulence. Stable reflection signals are maintained even in thick foam or vigorously stirred conditions.
• Suitable for Complex Conditions: Especially effective for high-viscosity media (e.g., beer fermenters, detergents), media with suspended particles (e.g., fruit juices, slurries), or low dielectric constant substances (e.g., light oils, liquefied gases), solving the issue of signal attenuation in non-contact radar.

2. High Measurement Accuracy and Stability

• Focused Reflected Signals: The guided probe concentrates microwave energy on the medium surface, resulting in strong, stable reflections. Measurement accuracy typically reaches ±0.05%FS with excellent repeatability (±0.02%FS).
• Unaffected by Tank Space: Suitable for small tanks, irregularly shaped vessels, or tanks with internal obstacles (e.g., agitators, baffles), as the probe propagates signals independently without interference from tank structures.

3. Installation and Maintenance Adapted to Medium Properties

• Installation Methods: Probes must be inserted into the medium. Material selection (e.g., 316L stainless steel, PTFE coating) and probe type (rod-type for low-viscosity liquids, cable-type for high-viscosity or deep tanks, coaxial-type for low dielectric constant media) depend on medium viscosity and corrosiveness.
• Maintenance Considerations: Contact with media may cause buildup (high-viscosity media), corrosion (strongly corrosive media), or scaling. Regular cleaning is required to prevent signal distortion, and probes risk breakage (anti-collision designs are needed for stirred environments).

4. Medium and Environmental Compatibility

• Medium Compatibility: Suitable for liquids, slurries, and solid particles, particularly excelling with low dielectric constant (εᵣ≥1.8), high-viscosity (e.g., asphalt, syrup), or easily crystallizing media (e.g., caustic soda solutions).
• Environmental Adaptability: Withstands high temperatures (-50℃~400℃) and pressures (up to 40MPa), making it suitable for extreme environments like petrochemical plants and storage tank farms.

Limitations

• Contact measurement limits its use in high-hygiene scenarios (e.g., aseptic pharmaceuticals) due to frequent cleaning validation requirements.
• Probe length is fixed, restricting measurement range (typically up to 30m), making it unsuitable for extra-large open vessels.
• High-viscosity or easily solidifying media may cause probe buildup, affecting accuracy; highly corrosive media require costly anti-corrosion materials.

III. Comparative Summary of Core Characteristics

Conclusion