What are the common misunderstandings in the use of gas detectors, and how to avoid them?
As we all know, gas detectors are instruments used to detect changes in the concentration of harmful gases in work sites. However, in the use of gas detectors, there may be issues of inability to use or damage. When choosing a reputable manufacturer, quality factors are only a part, and most of them are caused by improper selection and use. So what are the common misconceptions of gas detectors?
1, Misconception in acceptance: Testing with high concentration gas
Analysis: Many customers like to randomly use high concentration gases for testing during acceptance, which is very imprecise and can easily cause instrument damage. The detection range of the combustible gas detector is 0-100% LEL, which is one lower explosive limit (taking methane as an example, 0-5% vol), while the lighter gas is high-purity butane, far exceeding the detection range of the combustible gas detector!
When using lighter gas for testing, the sensor will be impacted by 2-3 times or even higher concentrations, which can cause early attenuation or deactivation of the chemical activity of the sensing element, resulting in a decrease in detection accuracy and sensitivity; Heavy damage will burn the platinum wire and render the sensor useless. It should be noted that sensor failure caused by high concentration gas impact is not covered by the manufacturer's warranty and requires replacement at their own expense.
Conclusion: Do not use lighter deflation to test combustible gas detectors! Gas detectors should avoid high concentration shocks, and standard gases should be used for testing to check their working conditions. Similarly, toxic gases should also avoid high concentration gas impacts.
2, Misconception in selection: Organic gases are used for combustible gas detection
Analysis: Most combustible gas detectors on the market use the principle of catalytic combustion. The principle of catalytic combustion is to use combustible gases to generate low-temperature flameless combustion on detection components with catalytic performance. The heat of combustion causes the temperature of the components to rise, thereby increasing the resistance value of the components. The change in resistance value is detected by a Wheatstone bridge to achieve the purpose of detecting the concentration of combustible gases.
Although in principle, as long as it can burn and release heat, it can be detected, people often say that catalytic combustion sensors can theoretically measure any combustible gas.
However, catalytic combustion sensors are not suitable for measuring long-chain alkanes, such as high flash point gasoline, diesel, aromatic hydrocarbons, etc. Compounds with more than 5 carbon atoms, such as benzene, toluene, and xylene, especially hydrocarbon compounds with benzene ring structures, have strong carbon chains that are difficult to break during catalytic combustion, resulting in incomplete combustion. Unburned molecules will accumulate on the surface of the catalytic beads, leading to the occurrence of "carbon deposition" phenomenon and hindering the subsequent combustion of other molecules. When carbon deposition reaches a certain level, combustible gas will not be able to effectively contact the catalytic beads, resulting in insensitive or even unresponsive detection. This is determined by the properties of the sensor itself and belongs to a selection error in the early stage.
Conclusion: Common organic volatile gases such as benzene, alcohols, lipids, and amines are not suitable for detection using catalytic combustion principles, and PID photoionization principles should be used for detection. Before purchasing a gas detector, it is important to consult with the product company to avoid similar errors.
