[Objective] Fires and explosions caused by gas leaks result in serious casualties and property damage. Therefore, the precise detection of gas leaks is crucial. The primary component of natural gas is methane, and gas leak detection aims to accurately detect methane gas. However, methane detectors may face interference from adverse environmental factors during the gas leak detection process, affecting the performance of the detectors.[Methods] This study systematically analyzed the influence of water immersion and the complex conditions of low-temperature immersion on the response characteristics of catalytic combustion methane detectors. The catalytic combustion methane detector was initially immersed for 15-180 mins. The detector's alarm concentration and response time were then tested to evaluate the impact of immersion on the alarm performance and response speed of the catalytic combustion methane detector. Subsequently, tests were conducted on the alarm concentration and response time of the catalytic combustion methane detector immersed for 15 and 30 min at environmental temperatures of 30, 15, and 0 ℃. Furthermore, an analysis was conducted on the reasons for the impacts of low temperature and water immersion on the catalytic combustion detector, considering factors such as resistance, absolute humidity, moisture content, and catalyst-specific surface area.[Results] The results revealed that immersion significantly reduced the sensitivity of the methane detector, with a 90.3 % increase in the alarm concentration after immersion. The time required for the display values of the detector to reach 90 % of the baseline value increased by 115 min. Compared with room-temperature immersion, low-temperature immersion resulted in a 23.3 % decrease in the alarm concentration. The time required for the display values of the detector to reach 90 % of the baseline value increased by 55 min, but the repeatability of the response time improved, with an average standard deviation reduced by 65.16 %. After immersion treatment, a thin film of water formed on the surface of the sensor, impeding the entry of methane gas into the sensor's interior and decreasing the internal methane concentration. Additionally, water immersion reduced the catalyst's specific surface area and led to catalyst poisoning, thereby diminishing the available adsorption sites for methane. Therefore, this increase in methane concentration was required for the detector to reach the alarm state. Moreover, the platinum wire heater of the detector showed more significant resistance changes at low temperatures, requiring less heat from the catalytic combustion reactions to achieve the necessary resistance change for triggering the alarm, thereby reducing the required methane concentration for the detector's alarm. The absolute humidity of the testing environment decreased by 92.9 % at low temperatures, reducing the impact of environmental humidity on the detector. Therefore, the low-temperature environment effectively mitigates the adverse effects of immersion on the detector.[Conclusions] This study examined the variations in the response characteristics of catalytic combustion methane detectors under low temperature and water immersion conditions. This study also analyzed the reasons for the impacts of low-temperature and immersion environments, thereby providing experimental evidence for addressing the impact of complex low-temperature immersion conditions on methane detector performance. The results are beneficial for enhancing the accurate detection of methane leaks.
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