What are the usage errors 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 the work site. However, in the use of gas detectors, there may be issues of being unusable or damaged. 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, Acceptance Misconception: Testing with High Concentration Gas
Analysis: Many customers like to randomly test high concentration gases 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 (using 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 subjected to 2-3 times or even higher concentrations of impact, which can cause early attenuation or deactivation of the chemical activity of the sensing element, leading to a decrease in detection accuracy and sensitivity; If it is severe, the platinum wire will be burned and the sensor will be scrapped. It should be noted that sensor failure caused by high concentration gas shock is not guaranteed by the manufacturer and requires self replacement.
Conclusion: Do not use lighter deflation to test combustible gas detectors! Gas detectors should avoid high concentration shocks, and the working condition should be checked using standard gas for testing. Similarly, toxic gases should also avoid high concentration gas impacts.
2, Misconception in Selection: Organic Gas as Combustible Gas Detection
Analysis: Most combustible gas detectors on the market use the catalytic combustion principle, which uses combustible gases to generate low-temperature flameless combustion on catalytic detection components. The heat of combustion causes the temperature of the components to increase, thereby increasing their resistance value. The change in resistance value is detected through 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, it is often said that catalytic combustion sensors can theoretically measure any combustible gas.
However, catalytic combustion sensors are not suitable for measuring long-chain alkanes, such as gasoline, diesel, aromatics, etc. with high flash points. Compounds with more than 5 carbon atoms, such as benzene, toluene, and xylene, especially hydrocarbons with benzene ring structures, have strong carbon chains that are difficult to break during catalytic combustion, resulting in incomplete combustion. Incomplete molecules will accumulate on the surface of the catalytic beads, leading to "carbon deposition" and hindering the combustion of other molecules. When the carbon deposition reaches a certain level, the combustible gas will not be able to make effective contact with the catalytic beads, leading to insensitivity or even unresponsiveness in detection. This is determined by the properties of the sensor itself, which is a preliminary selection error.
Conclusion: Common organic volatile gases such as benzene, alcohol, lipid, amine, etc. are not suitable for detection using catalytic combustion principle, and PID photoionization principle should be used for detection. Before purchasing a gas detector, it is important to consult with the product company to avoid similar errors.
3, Misuse: Unauthorized modification of usage environment
Analysis: The gas detector is designed to measure gas concentration values in the environment, and online measurement of hydrogen sulfide concentration in pipelines is a modification of the usage environment. The sensor of the hydrogen sulfide gas detector is based on the electrochemical principle, and the degree of electrolyte loss is positively correlated with the concentration of hydrogen sulfide in the environment. The more hydrogen sulfide content, the faster the electrolyte consumption and the shorter its lifespan. In a normal environment, the concentration of hydrogen sulfide is 0, and only leakage will consume the electrolyte, so the lifespan can reach 1-2 years. Hydrogen sulfide is constantly present in the pipeline, and the electrolyte is constantly consumed, greatly reducing the natural lifespan.
Conclusion: Gas detectors are suitable for environmental detection. When used for online analysis of pipelines, it is necessary to consult the manufacturer and do not change the usage environment without authorization.
4, Maintenance misconception: only using without maintenance
Analysis: Gas detectors belong to measuring instruments, and regular calibration is required to ensure the accuracy of their detection. Any gas detector will experience drift after long-term use, and if not calibrated in a timely manner, the error will increase, causing safety hazards. According to regulations, the maximum fixed cycle of gas detectors shall not exceed one year, and enterprises with specialized metrology departments are recommended not to exceed three months. The calibration of gas detectors needs to be operated by professionals.
Conclusion: Purchasing and installing a gas detector does not always guarantee its normal use. It should be updated and maintained regularly in the future. If problems occur, contact the product company immediately and do not repair it yourself. Avoid minor problems that can lead to significant losses due to negligence.
