
Choosing the Right Optical Gas Analysis Solution: A Complete Industry Guide
Selecting the right gas analysis system is crucial for ensuring safety, compliance, and efficiency across multiple industries. Optical gas analysis...
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Instrava provided the doas gas analyzer based on advanced UV Differential Optical Absorption Spectroscopy (DOAS) technology provides highly accurate and stable measurement of key gases such as SO₂, NOx, O₂, CO, and CO₂ in industrial emissions.
Designed for hot-wet extractive sampling systems, this analyzer eliminates gas loss caused by condensation, ensuring true and reliable measurement results, especially for SO₂ and reactive gases.
With a long-life xenon light source (up to 10 years), no moving optical parts, and automatic calibration capabilities, it delivers low maintenance, high reliability, and long-term stability, making it ideal for CEMS (Continuous Emission Monitoring Systems) and industrial process optimization.
Optical Analysis Description
Advanced Multi-Gas Analysis with DOAS Technology
This industrial DOAS gas analyzer integrates UV-DOAS + NDIR + electrochemical/zirconia technologies, enabling comprehensive gas monitoring in complex environments.
UV DOAS: SO₂, NO, NO₂ (NOx)
Zirconia / Electrochemical: O₂, H₂O
NDIR: CO, CO₂
Full-spectrum absorption analysis improves accuracy and selectivity
Automatic high/low range switching for wide concentration monitoring
PLS algorithm eliminates cross-interference from dust, moisture, and background gases
Stable performance in high humidity and high dust flue gas conditions
Power plants (coal-fired boiler emission monitoring)
Petrochemical and coal chemical industries
Industrial flue gas analysis
Environmental compliance monitoring systems (CEMS)


Industrial Reliability & System Integration Advantages
Engineered for continuous industrial operation, this online DOAS gas analyzer system offers strong system compatibility and long-term reliability.
Automatic calibration function reduces manual maintenance
Adjustable calibration cycle for long-term stable operation
No moving optical parts → higher durability and lower failure rate
Modular design with integrated heating system for hot-wet sampling
Multiple outputs: 4–20mA, RS232, RS485 (Modbus)
Supports PLC / DCS / SCADA systems
Multi-channel relay and switch inputs for automation control
Optical fiber gas cell design for easy maintenance and replacement
No condensation → no SO₂ loss
Higher wavelength resolution → better linearity and accuracy
Strong anti-interference → stable in moisture and dust environments
Lower maintenance → simplified sampling system
Optical Analysis Parameter
| Parameter | Specification |
|---|---|
| Technology | UV-DOAS |
| Installation | Hot-wet extractive |
| Measurement Range | 0–100 ppm / 0–200 ppm / 0–1000 ppm / 0–3000 ppm |
| Accuracy | ≤ ±1% |
| Linearity | ≤ ±1% F.S |
| Response Time | ≤ 60 s (T90) |
| Zero Drift | ≤ ±2% F.S |
| Span Drift | ≤ ±2% F.S |
| Parameter | Specification |
|---|---|
| Technology | Zirconia / Electrochemical |
| O₂ Range | 0–25% |
| H₂O Range | 0–40% |
| Response Time | ≤ 60 s |
| Linearity | ≤ ±2% F.S |
| Parameter | Specification |
|---|---|
| Technology | NDIR |
| CO Range | 0–1000 ppm |
| CO₂ Range | 0–20% |
| Accuracy | ≤ ±1% |
| Response Time | ≤ 60 s |
| Linearity | ≤ ±2% F.S |
| Parameter | Specification |
|---|---|
| SO₂ / NO Detection Range | 0–50 ppm to 0–5% |
| O₂ Range | 0–25% |
| Repeatability | ≤ 1% |
| Response Time | < 60 s |
| Ambient Temperature | 5°C ~ 45°C |
| Analog Output | 3 × 4–20mA |
| Analog Input | 2 × 4–20mA |
| Digital I/O | 4 inputs / 8 relay outputs |
| Communication | RS232 / RS485 (Modbus) |
| Power Supply | 220VAC, 50Hz |
| Power Consumption | 100W |
| Protection Grade | IP42 |
| Size | 19” 4U rack |
| Gas Interface | Ø6 mm |
Instrava OEM/ODM
Reliable Instruments. Solutions That Fit Your Application.
Instrava is focused on delivering reliable industrial solutions through carefully curated products, application-driven optimization, and flexible customization. We select proven instruments from trusted manufacturers to ensure consistent quality, optimize solutions based on real working conditions to solve practical challenges, and provide tailored configurations to meet specific application needs.
By combining selection expertise with application understanding, Instrava helps customers reduce risk, improve efficiency, and achieve dependable results in complex industrial environments.

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What is a DOAS gas analyzer and how does it work?
A doas gas analyzer uses UV differential optical absorption spectroscopy to measure gas concentrations based on their unique absorption spectra. It provides high accuracy and strong anti-interference performance, especially for SO₂ and NOx monitoring.
Why is a DOAS gas analyzer better for SO₂ and NOx measurement?
Unlike traditional systems, the DOAS analyzer uses hot-wet sampling, preventing condensation and eliminating SO₂ loss, ensuring more accurate emission data.
What is the difference between DOAS and NDIR gas analyzers?
A DOAS gas analyzer offers full-spectrum analysis, higher resolution, and better anti-interference, while NDIR analyzers rely on band-pass filters and are more sensitive to moisture and cross-gas interference.
Can a DOAS gas analyzer be used in CEMS systems?
Yes. It is widely used in continuous emission monitoring systems (CEMS) due to its high stability, low drift, and reliable long-term operation in industrial environments.
What industries use DOAS gas analyzers?
Common applications include power plants, petrochemical industries, coal chemical processing, and environmental monitoring projects, especially where accurate flue gas analysis is required.
How does automatic calibration improve DOAS analyzer performance?
The built-in automatic calibration function continuously corrects zero drift and maintains measurement accuracy, reducing manual intervention and ensuring long-term reliable operation.
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