Steps of the Working Principle for Gas Detectors
With the rapid development of society, people are paying increasing attention to work safety. Gas detectors also have broader development prospects and research directions. Diversified developments of gas detectors greatly improve experimental operations and safety assurance. The following introduces how gas detectors perform gas measurement.
The working principle of gas detectors can be divided into four steps:
① Gas detectors adopt advanced hardware from home and abroad. Such hardware draws in gas samples for analysis and detection. If certain target substances in the gas exceed or fail to meet standards, the alarm will be triggered.
② Gas detectors adopt a different measuring method. When gas enters the test chamber, a light beam is emitted. Half of the beam travels through the gas to a receiver, while the other part returns to the transmitter. The detector measures the intensity of the two beams to determine whether combustible gas exists. If the beam intensities remain consistent, no hazard is detected; a change in beam intensity on the gas path may indicate a fault or gas leakage.
③ Several points shall be noted for toxic gas detection. First, inherent characteristics of toxic gases should be considered, such as chemical stability and relatively high regulated concentration limits. Diffusion‑type detectors rely on natural air flow instead of active sample pumping, so they generally feature slow response times. Calibration of 4‑in‑1 gas detectors is often difficult and requires special accessories to convert the flow calibration mode to the diffusion operating mode. In addition, the equivalence between flow monitoring, calibration and diffusion sampling cannot always be well documented.
④ Calibration may become more complicated when adjustments need to be made on the control panel while calibration gas is applied to the remote sensor head of diffusion gas detectors. Interfering gases may exist in some application scenarios. The sample drawing method allows chemical scrubbers to be installed upstream of the sensor to absorb interfering substances. All gas sensors measure partial pressure. Sensors with active sample pumping work at slightly elevated pressure, while diffusion sensors operate under ambient pressure. Therefore, pumped sample sensors usually have higher output sensitivity than diffusion sensors, which is critical for many toxic gases with low permissible exposure limits. However, only a limited number of toxic gases possess the applicable properties.
