Correlation-based flow measurement for hot, heavily dust-laden gases, free of drift and calibration
Measuring the flow of a hot, dust-laden gas in a duct continuously, without purging or recalibration, takes a principle that does not depend on differential pressure: correlating the time of flight of the particles carried in the gas itself. The McON Air measures the time of flight of the signal patterns those particles create, picked up by its two probes, and delivers gas velocity (m/s) and volume flow (m³/h) with ±2% accuracy and a turn-down ratio of up to 25:1, in gases up to 1000 °C and with up to 2500 g/m³ of dust, with no K-factors and no auxiliary pressure or temperature measurements.
McON Air key data
- Measuring principle: patented correlation of the time of flight of the signal patterns generated by the particles in the gas itself; being a time measurement, the McON Air is accurate and drift-free over its entire lifetime.
- Gas conditions: temperature up to 1000 °C (1800 °F) and dust load up to 2500 g/m³, with no purging and no cleaning; dust does not disturb the measurement, because the particles create the signal.
- Accuracy and range: ±2% with a turn-down ratio of up to 25:1, so a single installation covers everything from minimum working flow to full load.
- Quantities and outputs: gas velocity in m/s and volume flow in m³/h over 4-20 mA outputs; the Portable version adds a 4-20 mA output for the plant control system.
- No calibration or compensation: no K-factors, no calibration of the sensors after installation and no auxiliary pressure or temperature measurements; the plausibility of the raw signals is monitored continuously.
- Installation: two flange-mounted probes, of different lengths depending on the duct diameter, with hot tapping without stopping the plant and a reading in m/s as soon as they are connected.
- Versions: Compact (fixed, single channel), SIL (SIL 2 certified for safety loops) and Portable (rugged cases even suitable for air travel and CSV logging on SD card for campaigns lasting weeks).
- Applications and payback: tertiary air, downcomer and clinker cooler in cement plants, electric arc furnace off-gas, primary and secondary air in power stations and total stack flow for emissions; usual return on investment under 3 months.
Advantages
Measures where other principles fail
Neither dust nor temperature degrades the signal: the system works with dust loads up to 2500 g/m³ and gases up to 1000 °C, with no purging and no periodic cleaning.
No drift, no recalibration, no K-factors
The direct time-of-flight measurement needs no correction factors and no pressure or temperature compensation, and the plausibility of the raw signals is supervised continuously.
Installation without stopping the plant
The sensors are mounted via flange and support hot tapping, so the installation does not force a process shutdown and requires no subsequent calibration of the sensors.
Turn-down ratio of 25:1
With a ±2% accuracy and a turn-down ratio of up to 25, the same installation covers everything from minimum working flow to full load.
Immediate payback
By eliminating maintenance, purging and recalibration, the usual return on investment is under 3 months, and the digital online measurement feeds the process control directly.
Applications
- Cement plants: tertiary air, downcomer, vertical raw mill, clinker cooler, bypass and waste heat recovery.
- Steelworks: electric arc furnace off-gas.
- Power stations: primary and secondary air, flue gas and unburned carbon.
- Waste-to-energy plants and emission monitoring, with the accurate measurement of the total stack flow.
About the product
The Compact version is the fixed single-channel solution: two probes in the duct and an evaluation unit with 4-20 mA outputs for velocity and volume flow. For safety loops there is the SIL variant, available as a SIL 2 version, and for measurement campaigns the Portable version brings the same principle to a mobile kit with rugged cases, CSV data logging on SD card, an additional 4-20 mA output and probes of different lengths.
The instantaneous reading in m/s is obtained as soon as the probes are connected, with no prior calibration. Available accessories: probes of different lengths for each duct diameter, SIL 2 certified version and complete portable kit.
Technical specifications
| Measuring principle | Correlation: time of flight of signal patterns |
| Gas temperature | Up to 1000 °C |
| Dust load | Up to 2500 g/m³ |
| Accuracy | ±2% |
| Turn-down ratio | Up to 25:1 |
| Outputs | 4-20 mA for velocity (m/s) and volume flow (m³/h) |
| Calibration and drift | No calibration, no purging, no K-factors |
| Versions | Compact (fixed single channel), SIL (SIL 2) and Portable |
| Probes and mounting | Two probes, length to suit the duct diameter; flange with hot tapping |
| Compensations | Unnecessary: no auxiliary pressure or temperature measurements |
| Logging (Portable) | SD card in CSV format; additional 4-20 mA output |
Frequently asked questions
What accuracy and turn-down ratio does the McON Air offer?
An accuracy of ±2% with a turn-down ratio of up to 25:1, so the same installation measures from minimum working flow to full load. It holds this in gases up to 1000 °C and with up to 2500 g/m³ of dust, with no purging or recalibration.
Does the McON Air measurement need pressure or temperature compensation?
No. By measuring the time of flight of the gas's own signal patterns, the McON Air obtains the actual flow with no auxiliary pressure or temperature measurements and no K-factors, and outputs velocity in m/s and volume flow in m³/h over 4-20 mA.
How can it measure with so much dust?
Because the particles themselves generate the signal patterns being correlated: the more heavily laden the gas, the clearer the signature the system measures.
Does it need recalibration over time?
No. Time-of-flight is a direct physical measurement, free of drift, and the system continuously checks the plausibility of the signals.
Is it suitable for emission monitoring?
Yes. It provides the accurate total stack flow measurement required for calculating mass emissions.
Can it be installed without stopping the process?
Yes. The flange mounting supports hot tapping, keeping full plant availability during installation.
Is there a version for spot measurements?
Yes. The Portable version offers the same principle in a mobile kit with SD card logging and a 4-20 mA output for connection to the plant control system.
