
Gas analyzers
SIRA ROA Premix
The SIRA ROA Premix is a specialized application of the stationary SIRA analyzer designed for the continuous determination of residual oxygen content following the combustion of premixed fuel gas/air mixtures. Precise control of the combustion process is essential for achieving maximum energy efficiency, consistent product quality, and minimal pollutant emissions.
The measurement principle combines a catalyst for oxidation of the gas sample with a zirconium oxide sensor for precise determination of the remaining oxygen content. This enables reliable monitoring of the combustion conditions and supports accurate adjustment of the fuel gas/air mixture.
A key feature of the SIRA ROA Premix is its very low gas consumption during the actual measurement process, achieved through a specially designed gas metering and mixing system. The reduced gas flow helps extend the service life of both the zirconium oxide sensor and the catalyst, resulting in lower maintenance requirements and reduced operating costs.
For reliable operation, the system provides automatic monitoring of all relevant measurement components. A controlled and adjustable bypass ensures fast response times, allowing changes in the process to be detected quickly.
Typical applications include fiber optic manufacturing and glass melting processes, where precise control of premixed combustion gases is critical for stable process conditions and consistently high product quality.
Key benefits: fast response time, low maintenance requirements, adjustable bypass, automatic catalyst monitoring, easy system integration, and multiple interface options.
| Technical data | Value |
|---|---|
| Dimensions H × W × D (mm) | 660 × 360 × 300, aluminum housing |
| Weight | Approx. 20 kg |
| Degree of protection | IP42 |
| Operating temperature | 5–50 °C |
| Ambient humidity | Max. 95% relative humidity, non-condensing |
| Fastening | Wall mounting, wall bracket included |
| Electrical connection | 110–230 VAC, 50–60 Hz, 185 VA |
| Display / Operation | 7"-touchscreen display |
| Gas inlet | Process gas, calibration gas, test gas |
| Gas connection | 6 mm stainless steel clamping ring |
| Process gases | Premixed fuel gases |
| Ambient pressure range | 950–1,100 mbar |
| Gas inlet pressure | 40–60 mbar |
| Gas consumption | 20 l/hour |
| Communication options | 0/4–20 mA, digital output, relay, fieldbus (optional) |
| Repeatability | ± 0.1 Vol. % |
| Range | 0.1% O₂ to 20.9% O₂ |
| Precision | ±2% of measured value or ±0.1% O₂, whichever is greater |
| Sensor flow | 2–3 l/h |
| Response time t₉₀ | < 5 s |
| Calibration gas suggestion | Air & O₂ in N₂ |
| Power supply | 115–240 V AC |
The SIRA product series in comparison

SIRA UV THT
Continuous measurement
of the odorant gas concentration

SIRA UV VOC
Measurement of volatile organic compounds (VOCs)

SIRA ROA Premix
Analysis of the residual oxygen content

SIRA CH₄ Low
Continuous measurement
of methane in exhaust gases
Industry applications
These products can be used in the following sectors.

Iron and steel production
Our appliance series have been used in iron and steel production for many decades.

Biogas
Union Instruments products have proven themselves extensively in biogas upgrading plants.

Petrochemicals and refineries
We produce customized and flexible measurement technology solutions for the petrochemical industry and refineries.

Glass and ceramics
Perfectly coordinated appliance technology for glass and ceramic applications that works both safely and economically.

Natural gas
Our INCA multi-gas analyzers provide efficient solutions for processes in natural gas plants.

Generating energy from waste
Our appliance technology makes an important contribution to the functionality of environmentally friendly and energy-saving system concepts.
Service
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Industries
Our key application areas at a glance.
We supply a wide range of industrial plants such as steel production, the natural gas industry and biogas producers.
Products
Special products for your industrial application.
Our range includes the INCA, CWD and SIRA product series and the CAM module – combined with top advice and service.