In a cement plant, a concrete batching plant, or a mine in West Africa, an incorrect level measurement in a silo is costly: clinker overflow, a grinder stopping due to lack of feed, a tanker truck leaving half-full, or incorrect stock inventory at the end of the month. The question arises for every project: should a radar or ultrasonic sensor be used to monitor the level of bulk products? This article breaks it down, with a focus on local constraints—dust, heat, the Harmattan, and procurement lead times.
Why Silo Level Measurement is a Critical Point
Cement and clinker silos, crushing hoppers, lime or activated carbon bins, aggregate stocks: the level controls all downstream production and determines the safety of the facilities. A false signal leads to either an overflow (product loss, cleaning, safety risk) or a feed interruption that immobilizes a grinder or a bagging machine. On a mining site, the stakes are the same as for conveyor belt availability: a single failing instrumented link is enough to freeze the entire chain.
Continuous Measurement or Point Level Detection: Two Distinct Needs
Before comparing technologies, the need must be clarified. Continuous measurement provides an exact height (4–20 mA signal) to know the stock at any time and automate filling. Point level detection is limited to a high or low alarm (on/off) to avoid overflow or dry running. Many silos combine both: a continuous level sensor for stock management, plus a high-level point detector for ultimate safety. Confusing the two leads to over-investing or, worse, leaving a silo without safeguards.
Continuous Measurement Technologies Facing Dust
Ultrasonic: Economical but Sensitive
The ultrasonic sensor emits a sound wave and measures the return time of the echo from the product surface. It is a non-contact, simple, and inexpensive solution, well-suited for liquids and silos with low dust levels. Its limitation is well-known: suspended dust, steam, high temperature variations, and ambient noise attenuate or blur the echo. However, the pneumatic filling of a cement silo generates precisely a dense dust cloud—the worst-case scenario for ultrasonic sensors.
80 GHz Radar: The Benchmark for Dusty Environments
Radar emits high-frequency electromagnetic waves (GHz range) that pass through dust and steam and remain insensitive to temperature, wind, or rain. Even if there is buildup on the antenna, the measurement continues to function. Modern 80 GHz sensors, such as the VEGAPULS 69 or the VEGAPULS SR 68 from VEGA, highly focus the beam: they target the bottom of the silo while avoiding the walls, reinforcements, and internal obstacles (ladders, bridge breakers), which makes the measurement reliable on silos of 30 m and more. With no contact, no wearing parts, and no maintenance, radar offers high availability—a decisive argument for continuous operation.
Point Level Detectors: The Safety Complement
For high or low alarms, vibrating fork or capacitive detectors are robust, inexpensive, and independent of the main sensor. Combining them with continuous radar measurement applies the right level of redundancy where a clinker overflow or dry running costs the most.
Radar or Ultrasonic: The Verdict for Dusty Silos
| Criterion | Ultrasonic | 80 GHz Radar |
|---|---|---|
| Dust Resistance | Low | Excellent |
| Temperature / Steam Sensitivity | High | Almost zero |
| Typical Range | Up to ~10–15 m | Up to 30 m and more |
| Maintenance | Regular cleaning | Maintenance-free |
| Equipment Cost | Lower | Higher initial purchase |
| Total Cost Over Time | Higher (downtime, drift) | Lower (reliability) |
In summary: for a powder silo subject to dust—cement, clinker, lime, coal, flour—the 80 GHz radar is the benchmark solution. Ultrasonic sensors still have their place in clean tanks, liquids, or very tight budgets in protected environments.
Choosing Wisely: Thinking in Total Cost of Ownership
The price of the sensor represents only a fraction of the real cost. One hour of grinder downtime, an overflow to clean, an incorrect stock weighing that skews purchasing: these items weigh much more heavily than the price difference between an ultrasonic and a radar sensor. It is the same total cost of ownership reasoning as for an electric motor: equipment that is slightly more expensive to purchase but maintenance-free and reliable over ten years is almost always the most profitable choice. The right decision criteria: nature of the product (grain size, angle of repose), silo height, presence of internal obstacles, dust level, temperature, and accuracy requirements for stock management.
The Realities of West Africa
In Burkina Faso and the sub-region, three factors reinforce the interest in radar. Dust, omnipresent during the dry season and accentuated by the Harmattan, often disqualifies ultrasonic sensors. Heat and day/night thermal variations disrupt temperature-sensitive measurements. Finally, procurement lead times and the limited availability of specialized technicians make a “maintenance-free” sensor that you install and forget invaluable. Choosing robust instrumentation from the start means avoiding repeated interventions that are difficult to fulfill locally.
GEMCO, Exclusive VEGA Representative in Burkina Faso
GEMCO is the exclusive representative of VEGA in Burkina Faso for instrumentation and measurement (level, pressure, point level detection). Beyond supplying the sensor, we support every project from start to finish: analysis of the need and the stored product, choice of technology and the appropriate model (VEGAPULS radar, point level detectors), installation, configuration, commissioning, and maintenance. This continuity—from advice to after-sales, with reliable stock and sourcing—secures the availability of your facilities over the long term.
FAQ
Is Radar Always Better Than Ultrasonic?
No. Radar is essential in dusty, hot environments or on tall silos. For a clean tank, a liquid, or a small silo in a protected environment, ultrasonic may suffice at a lower cost. The right choice depends on the product and site conditions.
Which Technology for a Cement Silo?
A non-contact 80 GHz radar (VEGAPULS type) for continuous measurement, ideally supplemented by a high-level point detector for anti-overflow safety.
Does a Radar Sensor Require Regular Maintenance?
No. With no contact and no wearing parts, it works even with dust deposits on the antenna, which significantly reduces maintenance interventions.
Can the Level of Highly Abrasive or Sticky Products Be Measured?
Yes, that is precisely the advantage of non-contact radar: no part touches the product, so there is no wear or clogging of the sensor. The choice of model and antenna is adjusted according to the product.
Does GEMCO Also Provide Installation and Commissioning?
Yes. As the exclusive VEGA representative in Burkina Faso, GEMCO provides advice, supply, installation, configuration, commissioning, and maintenance.
Conclusion
To make level measurement reliable in a silo subject to dust, 80 GHz radar is now the safest and most economical choice over time, while ultrasonic remains relevant for clean and protected applications. The real gain lies in the sizing: the right technology, the right model, and the right commissioning. Contact GEMCO for a recommendation tailored to your silo and to obtain a quote—we evaluate your needs and guide you toward the most profitable VEGA solution.
