Flammable gas and toxic gas detectors
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This post was last edited by zhoudingshengs on 2024-1-22 at 11:33. Discussion: 1. What measurement principle do combustible gas detectors used for measuring VOC volatile gases rely on? Is it catalytic combustion or gas-based? What are the measurement range and alarm values (H, HH)? 2. What measurement principle is used by the detector for detecting toxic benzene gases? Is it photoionization type or gas-type? What are the measurement range and alarm values (H, HH)?
1. Combustion-type gas detectors used for measuring volatile VOC gases generally operate on the principle of catalytic combustion, with measurement being carried out by detecting the oxidation reaction that occurs when the gas comes into contact with the surface of the catalyst. Its measurement range and alarm values vary depending on the specific model and brand. Generally, the measurement range of combustible gas detectors is usually between 0-100% LEL. The high alarm value H is typically 20-30% LEL, while the very high alarm value HH is generally 40-50% LEL. 2. Benzene toxic gas detectors generally use the photoionization measurement principle; by exposing the gas to ultraviolet light, ionization occurs, thereby allowing the concentration of toxic components in the gas to be measured. Their measurement ranges and alarm values also vary depending on the specific model and brand. Generally, the measurement range of toxic gas detectors is between 0-500 ppm, with the high alarm value at around 50-100 ppm, and the very high alarm value at 200 ppm or higher. .
1. Measuring flammability generally involves catalytic combustion and infrared spectroscopy； Measuring toxicity is generally done through electrochemistry or PID ； Oxygen is generally measured using electrochemical methods. For measuring VOCs such as benzene and toluene, the PID photodissociation principle is used. If I remember correctly, the detection limits for benzene at the first and second levels are 1.7 ppm and 3.4 ppm respectively; a measurement range of around 10 ppm should be sufficient. A slightly higher range is also fine, but if it’s too high, some people will say that the range is too broad
Measuring flammability generally involves catalytic combustion and infrared spectroscopy； Benzenes are generally measured using the PID photoionization principle ； The flammable gas alarm threshold H is 25% LEL, while HH is 50% LEL; for benzene, the alarm threshold H is 1.5 ppm and HH is 3 ppm, with a measurement range of 0–5 ppm