— Radar Level Measurement Technology and Application for Crude Oil Storage Tanks

Crude oil storage tanks are an indispensable link in the petroleum supply chain — from oilfield gathering stations, refinery feed tanks, to strategic reserve depots. Continuous, accurate level measurement is required not only for inventory management and custody transfer but also directly for production scheduling and tank farm safety.

Among the many level measurement technologies, radar level meters have become the mainstream choice for crude oil storage tanks due to their non‑contact operation, high accuracy, and immunity to process medium variations. Based on nearly five decades of instrument manufacturing and field application experience, Anhui Tiankang (Group) Co., Ltd. presents a systematic overview of radar level measurement for crude oil storage tanks, covering principles, selection guidelines, installation practices, and common troubleshooting.

1. Challenges of Level Measurement in Crude Oil Storage Tanks

Crude oil storage tanks present the following characteristics that challenge level measurement:

Traditional level measurement methods (float, servo, differential pressure) have various limitations: floats can stick, servo units have moving parts that wear, and DP is affected by density changes. Radar level meters largely overcome these issues.

2. Brief Working Principle of Radar Level Meters

Radar level meters emit high‑frequency electromagnetic waves (microwaves) toward the liquid surface. The waves reflect off the liquid surface and are received by the antenna. By measuring the time‑of‑flight (pulse radar) or frequency difference (FMCW), the distance from the antenna to the liquid surface is calculated, and then the level is determined.

$$L=H-\frac{c\times t}{2}$$

Where:

• $L$: Liquid level

• $H$: Mounting height (distance from reference point to antenna datum)

• $c$: Speed of light

• $t$: Time‑of‑flight

Frequency Modulated Continuous Wave (FMCW) is the dominant technology for crude oil tanks today. It transmits a continuously frequency‑modulated microwave and calculates distance by measuring the frequency difference between the transmitted and received signals. FMCW offers high signal‑to‑noise ratio, strong anti‑interference capability, and high accuracy. High‑frequency radar (e.g., 80GHz) has a narrower beam angle, concentrating energy and being less affected by internal obstacles and antenna fouling.

3. Types of Radar Level Meters for Crude Oil Tanks

Tiankang recommendation: For crude oil storage tanks, 80GHz high‑frequency non‑contact radar level meters are the preferred choice. Advantages:

• Beam angle typically ≤3°, less affected by internal obstacles

• Concentrated energy, good penetration through foam and vapour

• Simple installation, minimal maintenance

• Accuracy up to ±1~2 mm

4. Core Advantages of Tiankang Radar Level Meters for Crude Oil Tanks

Anhui Tiankang has developed a series of dedicated radar level meters for the specific conditions of crude oil storage tanks:

4.1 Strong Anti‑Interference Capability

• Advanced FMCW technology with dynamic gain adjustment effectively suppresses false echoes from fixed obstacles such as agitators and heating coils.

• Built‑in false echo storage function automatically identifies and ignores fixed interference.

4.2 Antenna Fouling Resistance

• PTFE lens antenna with a smooth surface that does not readily adhere crude oil or wax.

• Optional purging system using nitrogen or instrument air to periodically clean the antenna surface.

4.3 Adaptability to Complex Vapour Space

• High‑frequency microwaves are insensitive to hydrocarbon vapour, water vapour, and condensed droplets.

• Optimised algorithms can distinguish between foam and liquid surface echo, still reliably measuring level under foam conditions.

4.4 High Accuracy and Long‑Term Stability

• Accuracy ±1 mm, meeting inventory and custody transfer requirements.

• No moving parts — no wear, maintenance‑free for long‑term operation.

4.5 Complete Explosion Protection Certifications

• Flameproof (Ex d IIC T6) and intrinsically safe (Ex ia IIC T6) options available for Zone 1/2 hazardous areas.

• Antenna materials corrosion‑resistant for sour crude service.

4.6 Easy Installation

• Multiple process connections: flange (DN80~DN200), threaded, tri‑clamp.

• LCD display rotatable 360° for easy field reading.

• Supports HART, Modbus, Profibus PA, etc., for DCS/PLC integration.

5. Selection Guidelines for Crude Oil Tank Radar Level Meters

6. Installation Best Practices

Correct installation is the prerequisite for reliable radar level meter operation. Key points for crude oil storage tanks:

6.1 Installation Location

• Avoid over the inlet – Do not mount directly above the oil inlet, where surface agitation during filling is severe.

• Avoid over heating coils – Avoid mounting directly above heating coils, which can produce strong reflections.

• Avoid floating roof guide poles – For internal floating roof tanks, keep away from guide poles and other metal structures.

• Away from tank wall – At least 500 mm from the wall to avoid wall reflection interference.

• Optimum location – Typically at half‑radius of the tank roof, as far as possible from internal obstacles.

6.2 Flange Nozzle Height

• Keep the flange nozzle (stub) as short as possible, generally ≤150 mm.

• The inside of the nozzle should be smooth, free of burrs or weld protrusions.

• For insulated tank roofs, the nozzle should extend 50–100 mm above the insulation.

6.3 Distance Between Antenna and Maximum Liquid Level

• Ensure the distance from the lowest antenna point to the maximum liquid level is ≥ the antenna blind zone (typically 200–500 mm).

• For foaming service, allow extra margin.

6.4 Preventing Condensation and Fouling

• In cold climates, install an insulating spacer between the flange and nozzle to reduce temperature difference and prevent condensation.

• For severe fouling, install a purging system.

6.5 Electrical Connection

• Use shielded cable; ground shield at one end.

• Use Ex‑certified cable glands in hazardous areas.

• Ensure connection head is well sealed to prevent moisture ingress.

Tiankang service: Tiankang provides on‑site installation guidance, false echo tuning, and loop testing to ensure smooth commissioning.

7. Common Problems and Troubleshooting

8. Recommended Tiankang Radar Level Meters for Crude Oil Tanks

Tiankang advantages:

• Nearly 50 years of instrument manufacturing experience; mature, reliable products

• Complete Ex certifications (CCC/ATEX/IECEx) for export projects

• CNAS‑accredited laboratory for full performance testing

• Full technical support from selection, installation guidance, to commissioning and maintenance

9. Conclusion

Level measurement in crude oil storage tanks demands high accuracy and reliability. Radar level meters — especially 80GHz high‑frequency non‑contact radar — have become the preferred solution due to their strong anti‑interference capability, high accuracy, and maintenance‑free operation.

Anhui Tiankang (Group) Co., Ltd. offers radar level meters specifically optimised for the challenging conditions of crude oil storage tanks. With professional installation guidance and comprehensive after‑sales support, Tiankang provides stable, accurate level measurement solutions for your tank farm.

Contact Us

For radar level meter selection advice, technical documentation, or project quotations for crude oil storage tanks, please contact:

Yin Shuangjie
📧 Email: [email protected]
📱 WhatsApp / Zalo: +86 17856068126
🌐 Website: http://www.tiankang-global.com/

Anhui Tiankang — Your level measurement expert for crude oil storage tanks.