Temperature, humidity, pressure and the properties of the gas sample can have a considerable effect on measurement accuracy. In industrial applications, where precise gas measurements affect process quality, efficiency and safety, it is worth taking a closer look at possible sources of interference.
1. Temperature: When heat affects the measurement
Gas sensors do not operate independently of their surroundings. Rising or falling temperatures can affect both electronic components and the physical properties of the gas being measured.
In NDIR gas sensors, this can affect the infrared source and the detector, for example. Rapid temperature changes in particular can cause temporary measurement deviations.
The solution: Appropriate temperature compensation reduces these effects. However, the sensor must be designed for the actual temperature range of the application.
2. Humidity: An underestimated source of interference
Water vapour can affect gas measurement in different ways. In optical measurement methods, humidity can interfere in certain absorption bands.
The problem becomes more serious when water vapour condenses. Liquid droplets can affect optical components and block gas pathways.
The solution: Depending on the application, controlled gas conditioning, suitable filters or drying the gas sample can help. These measures must not alter the concentration of the target gas beyond acceptable limits.
3. Pressure fluctuations: Same concentration, different signal
Gas pressure is an often overlooked factor.
NDIR measurement detects how strongly certain gas molecules absorb infrared radiation. When the pressure changes, the number of molecules in the optical path also changes. This can alter the measurement signal even though the relative proportion of the target gas remains the same.
The solution: Appropriate pressure compensation or controlled sampling can help reduce these deviations.
4. Contamination: When the gas sample becomes a problem
Dust, aerosols and other contaminants can accumulate in measurement systems. In industrial processes with contaminated gas streams in particular, this can affect measurement quality over time.
In optical sensors, contaminated measurement cells can alter light transmission. Clogged filters or gas lines can also delay measurement results.
The solution: Gas conditioning tailored to the application and regular checks of the measurement path help maintain measurement quality over the long term.
5. Incorrect calibration: When the reference value is no longer correct
Not every measurement deviation is caused by external factors. Unsuitable or incorrectly performed calibration can also produce incorrect readings.
For example, using unsuitable calibration gases or failing to maintain the required calibration conditions can cause systematic deviations.
The solution: Calibration intervals and test procedures should follow the manufacturer's specifications, the operating conditions and the accuracy requirements of the application.
Precise gas measurement starts with the operating conditions
Modern NDIR gas sensors offer high selectivity and long-term stability. Even so, measurement quality depends on the entire measurement system as well as the sensor.
smartGAS develops NDIR-based sensor solutions for a range of industrial requirements. Depending on the sensor model and application, integrated compensation functions and suitable gas conditioning components support reliable measurement even under demanding conditions.
Conclusion: If a gas sensor shows incorrect readings, this does not necessarily mean it is faulty. It is often worth checking temperature, humidity, pressure, gas handling and calibration first. Considering these factors during system design lays the foundation for precise, reliable measurement results over the long term.
Would you like to find out which sensor solution suits your measurement conditions? The smartGAS team can help you select and integrate suitable gas sensors.