ব্লগ সম্পর্কিত What are the application scenarios of O2-A2 oxygen sensors? How to use it to make product performance more stable?

What are the application scenarios of O2-A2 oxygen sensors?

1>. Portable gas detector: four in one/multi in one gas detector, O ₂ oxygen deficiency alarm, safety inspection before personnel enter confined spaces, environmental inspection of mines, underground pipelines, storage tanks, etc
2>. Fixed oxygen detection/alarm systems: industrial plants, chemical, petrochemical, steel, metallurgy, coal mines, and underground spaces,
Laboratory and equipment room
3>. Medical and related equipment: certain oxygen concentration monitoring devices, respiratory/gas analysis related equipment
4>. Atmosphere analysis: inert gas protection environment, monitoring of oxygen content in nitrogen/argon and other environments, oxygen deficiency detection in enclosed equipment, industrial process gas analysis
5>. Combustion and industrial process monitoring: furnace and combustion related atmosphere detection, oxygen concentration monitoring in industrial equipment
However, if the temperature is high and contains a large amount of corrosive/polluting gases, O2-A2 cannot be directly placed in high-temperature flue gas, but needs to be sampled, cooled, filtered, and measured.

How to use it to make product performance more stable?

This is actually more important than the indicators of the sensor itself. O2-A2 is an electrochemical sensor, and the final overall performance is equal to the sensor+air circuit+circuit+temperature and humidity/pressure+calibration algorithm.

Firstly, control the working environment within the specified range and try to make the sensors work in:
Temperature: -30~55 ° C, pressure: 80~120 kPa, humidity: 5~95% RH, non condensing, avoid direct contact of liquid water and condensed water with the sensor, these are the key environmental specifications for O2-A2. Pay special attention to condensation.

For example, if a device is suddenly taken from a 5 ° C warehouse to an environment of 30 ° C and 90% RH, condensation may occur inside the sensor and housing. At this point, even if the environment itself does not exceed the long-term operating temperature range, the measurement may drift for a short period of time.

Suggestion:
The shell design prevents water droplets from directly entering the sensor; Consider dust and water prevention at the entrance of the gas path; Add hydrophobic and breathable membranes in high humidity environments; Avoid installing sensors in locations that are prone to water accumulation; Equipment with large temperature differences should be designed with sufficient temperature equilibrium time.

2. The sensor should not be directly exposed to "dirty gases". The gas inlet of O2-A2 needs to be connected to the measured gas, but dust, oil mist, droplets, silicon pollutants, corrosive gases, etc. can all affect long-term stability.

If used in industrial sites, it is recommended to use: tested gas → dust-proof/hydrophobic filtration → necessary condensation treatment → O2-A2 → signal processing.
Instead of directly flushing sensors with industrial flue gas, especially in scenarios such as boilers, combustion, and chemical production, the gas composition needs to be confirmed first.

3. Pay attention to the effects of accompanying gases such as CO ₂, as O2-A2 is not completely insensitive to all gases.

One indicator given by the data is that under the condition of 5% CO ₂, CO ₂ has a certain impact on the output.
So if your actual application is fermentation, breathing gas, CO ₂ protective gas, food packaging, bioreactor, high concentration CO ₂ environment, don't simply think that "all measured changes are O ₂ changes". It is best to conduct a cross sensitivity verification using the actual gas composition.

4. In terms of calibration, it is recommended to do so. For most O2-A2 applications, at least:

Zero point calibration: Use anaerobic/low oxygen gas for zero point inspection, such as a suitable nitrogen environment.
Span calibration: Use a known concentration of oxygen standard gas for range calibration.
The O ₂ in the air is approximately 20.9%, so many products use ambient air as a daily span checkpoint. However, if your product requires high accuracy, it is recommended to use certified standard gases for formal calibration.
The output specification of O2-A2 at 20.9% O ₂ is about 80 – 120 μ A, and there are individual differences between different sensors, so do not convert all sensors directly according to a fixed current value.