Frequently Asked Questions - Gas Sensor Technology
Frequently Asked Questions
Q: What is the difference between infrared and electrochemical gas sensors?

A: The main difference is in the measurement method. In electrochemical sensors, the sensitive element remains in direct contact with the gas and a chemical reaction occurs. This causes the sensor element to be contaminated by the reaction products which leads to loss of sensitivity, accuracy and calibration (drift). Most electrochemical sensors also are not very gas-specific. The infrared gas sensor, on the other hand, operates by measuring how much infrared light passing through a volume of gas is absorbed by the gas molecules, the gas being separated from the sensor components by IR-transparent windows. Moreover, infrared does this very specifically for each kind of molecular gas.

Q: Do the SmartScan sensors use ABCLogic(tm) or other similar algorithms to "self calibrate"?

A: SmartScan sensors do not use "self calibrating" algorithms, and do not require daily resetting/calibrating as "self calibrating" sensors do. "Self calibrating" sensors typically require a minimum of 4 hours excess ventilation of empty rooms/buildings, to be performed every day to carry out the selfcalibration process. This increases operational cost of the ventilation system and significantly reduces any energy savings. Such "self calibrating" sensors therefore are not suitable for buildings operating on a 24 h basis or where the aim is energy savings and/or demand controlled ventilation.

Q: How do the SmartScan sensors achieve their long term stability?

A: SmartScan sensors operate very close to the theoretical limits set by physical laws, and so their performance as well as the effects of any external influences can be exactly calculated, prepared and compensated for over time. This is due to the unique qualities of our own patented IR source, in combination with advanced digital electronics and software control.

Q: Can SmartScan infrared gas sensors detect all kinds of gases?

A: We regularly have requests for measurements of gases that cannot be detected by infrared technology. The reason for this is that only gases whose molecules contain two unequal atoms can be seen by infrared. Thus gases like N2 (nitrogen), O2 (oxygen), H2 (hydrogen), Cl2 (chlorine) etc cannot be detected in the IR (although we do have ambitions about the O2), and the same is the case for the noble gases He (helium), Ne (neon), Ar (argon), Kr (krypton), Xe (xenon), Rd (radon), which molecules consist of a single atom and thus there are no infrared vibrations possible because that requires at least two atoms to vibrate against each other (and then only unequal atoms). Essentially all other gases except those mentioned can be detected by our IR sensors.

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