Silicon dioxide, commonly known as silica, is crucial across many industries – from paints and plastics to food and pharmaceuticals, and the production of modern insulating materials. In chemical process engineering, this very fine, often fluidized powder imposes strict requirements on storage, conveying, and level measurement.
A project in insulation material manufacturing demonstrates how UWT sensor solutions provide reliable measurement results even under these challenging conditions, supporting process safety from filling to discharge.
The Challenge:
Fluidized Silica in a Dusty Atmosphere
In a plant producing heat and sound insulation boards, highly dispersed silica is temporarily stored in silos approximately 25 meters (82 feet) high. The material is pneumatically conveyed into the silos, resulting in a very loose bulk density of less than 20 g/l (1.25 lb/ft³) and generating significant dust. These conditions make reliable level measurement especially difficult.
Additionally, during discharge through a silo cone, typical bulk material cones form, which can cause bridging and flow interruptions – adding another challenge for the sensors.
Measurement Tasks: Combined Level and Point Level Detection for Light, Fine-Grained Bulk Solids
Continuous level measurement for inventory monitoring
Point level detection for full and empty indication in process control
Material flow monitoring in the discharge pipe for early detection of blockages
Our Solution Perfectly Tailored to the Finest Powder
– Continuous Measurement Under Extreme Conditions
For level measurement, the NivoRadar® NR 3300 with lens antenna was selected – a sensor that delivers precise and stable signals even with very low dielectric constants and heavy dust loads.
3° narrow beam angle (80 GHz): ideal for tall, slender silos
Swivel flange (up to ±10°): alignment to bulk cone and silo bottom with cone
UWT LevelApp with alignment assistant: visual adjustment & simple commissioning
Purge air connection with check valve: protects the lens antenna from dust build-up
Robust materials: 316L, PEEK, FKM – suitable even for use in sensitive areas
Consistently Precise Measurement in Powder Processes – with the NR 3300 and Its Optimally Aligned, Self-Cleaning Lens Antenna
Thanks to the adjustable flange, the radar beam could be precisely aligned with the material surface and the conical bottom. The integrated purge air function keeps the antenna free from dust permanently, especially during filling, ensuring consistently accurate measurement results.
with Vibrasil® – Point Level Detection for Extremely Light Materials
For point level measurement, Vibranivo® level limit sensors with Vibrasil® technology were used. They are specially designed for fluidized, ultra-light powders – providing extremely high sensitivity and fast response.
Learn more about reliable level and point level detection in fine powders:
VN 2020 with the sensitive Vibrasil® 70 Probe Detects Even the Lightest Materials
Applications in Detail
Full detection:
Beneath the silo roof, the VN 2020 with Vibrasil® 70 detects the loosened silica surface – even when the material is airborne.
Empty detection:
Within the lower silo section, the VN 2020 with Vibrasil® 90 reliably signals empty status. The extended, polished tuning fork responds sensitively, even with low-density materials.
Material flow monitoring:
In the discharge branch, another VN 2020 with Vibrasil® 70 reliably detects flow status – for example, when using discharge aids such as pneumatic conveying or vibration – protecting the process from downtime.
Process Conditions
| Type | Solids |
| Material | Highly dispersed silica (SiO₂) |
| Bulk density | < 20 g/l | 1.25 lb/ft³ (fluidized) |
| Silo height | approx. 25 m | 82 ft |
| Temperature | up to +60 °C | +140 °F |
| Explosion protection | Zone 21 |
Explosion Protection Included – Ready for Use in Hazardous Areas
With fine, dry silica, there is always a risk of creating an explosive dust atmosphere during pneumatic conveying or injection processes. In such cases, sensors must not only measure reliably but also meet the highest safety standards.
Both the NivoRadar® NR 3300 and the Vibranivo® feature international Ex certifications (e.g., ATEX, IECEx, cFMus), making them ideal for use in Zone 20/21. This guarantees the entire process remains precise and safe – even under difficult conditions.
Process Stability at every Stage
By combining continuous radar measurement with point level detection, complete monitoring from filling and storage through to discharge was achieved. Despite extremely fine particles, air, and dust, the sensors provide stable, reliable measurement values – all while keeping maintenance requirements low.
Whether radar or vibration technology – UWT provides the right solution for every bulk solid application in the process industry. With advanced technology, robust design, and smart tools like the LevelApp, your process stays safely on track – even with challenging powders such as silica.
