Laboratory infrared gas analyzer

NegotiableUpdate on 01/19

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Overview

Laboratory infrared gas analyzer is a precision instrument based on the principle of infrared absorption spectroscopy, used for detecting and analyzing gas components and concentrations. It is widely used in environmental monitoring, industrial process control, scientific research experiments, medical diagnosis, safety protection and other fields. Its working principle is mainly based on the physical property that "different gas molecules have characteristic absorption peaks for specific wavelengths of infrared light".

Product Details

When infrared light passes through the gas under test, gas molecules absorb specific wavelengths of infrared light corresponding to their molecular vibrations and rotor energy level transitions. By measuring the degree of attenuation of light intensity and combining it with Lambert Beer's law, the concentration of the target gas can be calculated. This law states that the degree of light absorption is directly proportional to gas concentration and optical path length.

A typical laboratory infrared gas analyzer consists of the following core components:

Infrared light source: A stable broadband infrared radiation source, such as ceramic heating elements or silicon carbide rods, is usually used to provide continuous infrared spectra.

Sample chamber (gas chamber): a chamber through which the gas to be tested flows, with its inner walls specially treated to reduce adsorption and reflection interference. The length of the gas chamber (optical path) is designed according to the detection sensitivity requirements, and a long optical path can improve the detection capability of low concentrations.

Optical filtering system: used to separate the light with the characteristic absorption wavelength of the target gas. Common techniques include narrowband interference filters (NDIR, non dispersive infrared) and Fourier transform infrared (FTIR) interferometers. NDIR technology has a simple structure, low cost, and is suitable for detecting a single or a few gases; FTIR can simultaneously analyze multiple gases with high spectral resolution, making it suitable for analyzing complex mixed gases.

Detector: Convert the infrared light signal after passing through the gas into an electrical signal. Common detectors include thermopiles and photoconductive detectors (such as lead sulfide and mercury cadmium telluride). Modern instruments often adopt dual channel or reference channel designs, which effectively eliminate light source fluctuations and environmental interference by comparing the signals of the measurement light path and the reference light path, and improve measurement stability.

Signal processing and control system: including amplification circuit, analog-to-digital converter, and microprocessor, responsible for data acquisition, algorithm processing, concentration calculation, and result display. Modern instruments are typically equipped with digital communication interfaces that enable remote monitoring and data transmission.

Infrared gas analyzer has many advantages: good selectivity, not easily affected by cross interference of other gases (can be effectively distinguished through filter or spectral analysis); Fast response speed, usually completing measurements within seconds to tens of seconds; No need to consume reagents, low operating costs; Continuous online monitoring can be achieved.

Common measurable gases include carbon dioxide (CO ₂), carbon monoxide (CO), methane (CH ₄), sulfur dioxide (SO ₂), nitrogen oxides (NO ₓ), volatile organic compounds (VOCs), etc. For example, in greenhouse gas monitoring, high-precision infrared analyzers are used to measure the concentration changes of CO ₂ and CH ₄ in the atmosphere; In coal mine safety, it is used for real-time monitoring of underground CH ₄ concentration to prevent explosions; In respiratory analysis, it can be used to detect CO or NO in human exhaled breath, assisting in disease diagnosis.

However, this technology also has limitations: it cannot detect diatomic molecules (such as O ₂, N ₂, H ₂) and inert gases due to their lack of infrared absorption properties; Water vapor and dust may interfere with the measurement, and dehumidification and filtration devices need to be equipped; Regular maintenance and calibration are required in high humidity or polluted environments.

In summary, laboratory infrared gas analyzers have become a major player in the field of gas analysis due to their high sensitivity, selectivity, and stabilityCannot be omittedThe tools. With the development of sensor technology, miniaturized optical components, and artificial intelligence algorithms, future infrared gas analyzers will continue to evolve towards miniaturization, intelligence, multi-component integration, and low cost.