Pyroelectric Detectors in Gas Analysis

A large number of gases absorb infrared radiation by intramolecular vibrations. For each specific material, the absorption intensity depends on the wavelength of the infrared radiation. This principle uses a non-dispersive infrared gas analyzer (NDIR gas analyzer) for gas analysis. The analyzer consists of an electronically or mechanically modulated infrared source, a sample cell through which the gas flows to be measured, and a pyroelectric detector.

In the detector cap, a narrow band pass filter (NBP Filter) is integrated, whose pass band corresponds to the absorption wavelength of the target gas. With the thermal detector, the transmission of the measured gas mixture is determined in a defined arrangement. If the gas being searched for is not present, most of the infrared radiation will reach the detector and the signal will be at its maximum. If the concentration of the gas increases, absorption will also increase according to Lambert-Beer's law, and the signal will reduce accordingly.

This concept finds itself again in standard InfraTec infrared filters with a center wavelength (CWL) of 4.27 µm and a half power bandwidth (HPBW) of 170 nm are suitable for the measurement of carbon dioxide (CO2), for example.

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Multi-channel Measurement

NDIR gas analysis cannot resolve complex forms of absorption bandwidths. Instead it uses an averaged signal measurement within the filter pass band. With this, you now have a manageable, long-time stable and continuously operating measurement method for industrial gas analysis at your disposal. Gas identification and transverse sensitivity of gas mixtures often require spectral multi-channel evaluations.

The classic gas analysis setup with filter wheel and/or mechanical chopper requires relatively fast (> 200 Hz) pyroelectric detectors with strong output signals. For this purpose, we offer multiple types with integrated JFET or CMOS operational amplifiers and pyroelectric elements, which are wired up for current mode operation.

Pyroelectric Detectors for Infrared Flame Sensor / Infrared Flame Monitoring

LME-335/LME-336

a measuring channel, high power, temperature compensation, reduced acceleration response, single or split power supply

LIM-262/LIM-272

a measurement and a reference channel, temperature compensation, single or split power supply

Safety in Mines - Picture Credits: © TTStudio / Fotolia.com

Safety in Mines

Firedamp explosions are not uncommon in the mining industry. In this case, a mixture of methane and air inflames. Therefore, the detection of methane is critical to ensure the safety of miners, for example. Many customers use our highly reliable pyroelectric detectors in their devices to protect the lives of people who work underground.

Anesthesia Monitoring - Picture Credits: © Beerkoff / Fotolia.com

Anesthesia Monitoring

Gas detection also plays a role in hospitals. There, detectors found in measuring instruments in the operating room control the use of anesthesia. With help from medical analyzers that are equipped with infrared detectors from InfraTec, doctors can very precisely adjust the particular anesthetic gas mixing ratio needed and continue to monitor it.

Awite’s non-dispersive multi-gas sensor is suitable for biogas analysis due to lower drift rates and improved transverse sensitivity to other hydrocarbons

Energy Miracle with Natural DNA

What does your breakfast egg from the weekend, a cornfield and a large portion of french fries from a fast-food restaurant have in common? They all provide raw materials for a biogas plant. Organic substances such as egg shells, corn or potato peelings are decomposed there naturally under airtight sealing. The result is an energy-rich and extremely versatile product – biogas.

Prototype for respiratory gas analysis of Geratherm Respiratory GmbH’

Health Care in One Breath

„Please strip to the waist.“ Medical examinations still frequently begin with this sentence. Still. This sentence could very soon be: „Please breathe out strongly.“ For research in the field of respiratory gas measurement systems are making considerable progress. The aim is clear: To make the diagnosis of illnesses easier and painless.

Detection of Gas Leaks

A pyroelectric sensor generates a signal as soon as it is illuminated with an electrically or mechanically modulated infrared source. By integrating a gas-specific narrow band pass filter, which is tuned to a specific gas, the pass band is spectrally limited. The installation of a CO2 standard filter with a CWL of 4.27 µm and a HPBW of 170 nm means that only radiation in this wavelength range will impact with the pyroelectric chip. If a gas begins to leak - in this case, CO2 - less radiation hits the detector and the signal gets weaker. The use of a second so-called reference channel with e.g. a CWL of 3.95 µm and a HPBW of 90 nm enables a more accurate detection of gas leaks that is less prone to error.

Alcohol Test

Instruments for breath alcohol control for motorists are also among the application areas of gas detectors. The very precise measurements serve the police as evidence of alcohol or drug abuse behind the wheel.

Plant Health

With pyroelectric detectors, even the photosynthetic metabolic processes of plants can be monitored. Especially the measurement of CO2 is of interest here.

Oil Production

A number of companies use infrared detectors for both high-temperature drilling operations as well as for work that lasts for days. Here, the gas concentrations can be measured and thus the rate of penetration controlled.

Oil Production - Picture Credits: © Michael Rosskothen / Fotolia.com

Detection of Disease

Certain diseases cause specific patterns of exhaled air. For the past few years, NDIR gas analysis has provided an additional opportunity for diagnosis, for example of cancer or gastric diseases. In these cases, bacteria such as Helicobacter pylori can be detected by a non-invasive method. A special substance will be taken by the patient. At presence of helicobacter pylori bacteria it generates C13 carbon atoms. Those can be measured by the NDIR method simply analyzing the exhalation air.

Water and Steel Analysis

Infrared detectors are used in devices that identify impurities in materials having different physical states. With liquids like water, a sample is cooked and the gases released are measured. A similar test method is used in the manufacturing of steel. This is to ensure the proper composition of the steel alloy. Here, steel pellet samples are heated and the concentration of the gases produced is analyzed.

Detector Search

InfraTec offers five different product groups including approximately 50 standard pyroelectric detectors. Choose your suitable infrared detectors with the help of our detailed detector search.

Overview of all standard infrared detectors
Sensor division InfraTec detectors overview