The dead zone (also known as blind zone or near zone) of a radar level transmitter refers to the region near the radar sensor where accurate measurement is not possible. Proper configuration of this zone is critical for ensuring reliable and precise level measurement. This guide outlines standard practices, influencing factors, configuration steps, and application recommendations for dead zone settings.
1. Typical Dead Zone Standards
1.1. Dead Zone Range by Radar Type
| Radar Type | Typical Dead Zone Range |
|---|---|
| Standard Radar (24–26 GHz) | 0.2 – 0.5 m |
| High-frequency Radar (80 GHz) | 0.05 – 0.2 m |
| Guided Wave Radar | 0.05 – 0.3 m (depending on probe type and medium) |
⚠️ Note: Higher frequency and smaller range radars usually feature shorter dead zones.
1.2. Relationship with Measuring Range
Dead zone typically occupies 5% to 10% of the total measuring range.
For a 5 m range, the dead zone is usually 0.25–0.3 m.
For small range models (e.g., 0.6 m), the dead zone might be proportionally larger, e.g., 0.05 m.
2. Factors Influencing Dead Zone Settings
2.1. Medium Characteristics
Low dielectric constant media (e.g., liquefied gas, hydrocarbons) tend to reduce signal strength, requiring a larger dead zone.
High dielectric constant media (e.g., water, slurry) allow more accurate detection closer to the sensor.
2.2. Installation Environment
Obstructions near the antenna (e.g., baffles, internal ladders) can cause false echoes — increase dead zone accordingly.
For guided wave radar, the dead zone is usually at the bottom of the probe (e.g., 0.1–0.3 m from the probe tip).
2.3. Process Conditions
High temperature, pressure, or corrosive atmospheres may cause sensor fouling — reserve extra dead zone to compensate.
Vapor layers (e.g., in volatile liquids like gasoline) may produce false reflections — dead zone must exclude this area.
3. Key Principles for Dead Zone Configuration
3.1. Avoid Obstructing Usable Measuring Range
The dead zone must be configured outside of the actual usable level range.
For example, in a 3 m tank with a 0.3 m dead zone, the measurable range is 0.3–3.0 m.
If level must be measured down to 0.2 m, consider switching to a radar with a shorter dead zone (e.g., 0.1 m).
3.2. Adjust for Special Mounting Conditions
If mounted near a tank wall or angled nozzles, increase dead zone slightly to avoid interference.
For guided wave radar, set dead zone based on probe geometry (e.g., distance from the probe tip to tank bottom).
3.3. Account for Safety Margins
Overfill protection: add a safety distance (e.g., 0.1 m) above the highest fill level to prevent overflow.
Cone- or dome-bottom tanks may require custom zero-point calibration.
4. Step-by-Step Setup Procedure
4.1. Parameter Configuration
Enter instrument setup menu.
Navigate to the “Dead Zone” or “Minimum Measuring Distance” setting.
Input the appropriate value (e.g., 0.3 m).
Save changes and reboot the device if necessary.
4.2. Commissioning and Verification
Perform simulated filling/draining to validate level tracking.
Use false echo suppression or “echo mapping” functions to eliminate unwanted reflections.
Regularly inspect and recalibrate to ensure long-term accuracy, especially when process conditions vary.
5. Industry Recommendations & Standards
| Source | Recommendation |
|---|---|
| Manufacturer Guidelines | Default dead zones vary by model — always refer to datasheets |
| Oil & Gas Sector | Recommended dead zone ≥ 0.3 m |
| API Standards | Ensure minimum measurable level is outside the dead zone |
6. Practical Example
Scenario:
Measuring water in a 5-meter vertical storage tank.
Radar: 80 GHz, high dielectric constant medium.
Recommended dead zone: 0.3 m
Measuring range: 0.3 m – 5.0 m
If minimum level to be measured is 0.2 m:
➜ Upgrade to a radar with a 0.1 m dead zone or reposition the sensor accordingly.
7. Common Mistakes to Avoid
❌ Setting dead zone = 0 — may cause erratic readings due to internal reflections.
❌ Ignoring false echoes from vapor or tank geometry.
❌ Failing to recalibrate after maintenance, media changes, or aging equipment.
❌ Assuming all radar sensors have the same default dead zone.
8. Suggested Visual Aids (Add to Article Layout)
Dead Zone vs. Measuring Range Diagram
High-Frequency vs. Low-Frequency Radar Comparison
Guided Wave Probe Structure & Dead Zone Illustration
Calibration Interface Screenshot (Instrument Menu)
Conclusion
Accurate dead zone configuration is a key determinant of radar level transmitter performance. By tailoring dead zone settings to the application environment, medium properties, and sensor specifications, users can significantly enhance measurement reliability and avoid operational issues such as overflow, underfill, or signal loss.