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The Zhengyuan Technical Services Team went to the site to resolve faults with the decarbonization control valves. Author/Source: Yangmei Zhengyuan Group; Date: 2020-12-24; Clicks: 13. Zhengyuan Fertilizer’s technical services team handled a project related to the valve position monitoring of the PSA decarbonization unit at Hubei Xinxixi Chemical. Electromagnetic devices were used for this purpose, but there was a fault with the valve No. 110 in Tower 1, preventing the status of the valve from being displayed – which posed a risk to the proper operation of the unit. Based on past experience, the technical service team believes that the issue is caused by damage to the magnet installed inside the cylinder; since it is not possible to inspect or replace the magnet while the machine is in operation, the fault has remained unresolved. After the unit was shut down, this valve was inspected, and the magnet and contacts were replaced. Despite troubleshooting, it still could not indicate the valve position properly; however, when the magnet made contact with the contacts, the valve position indication and alarm functions worked normally. In response to this situation, the technical service team analyzed that it might be due to the large distance between the contact and the magnet, resulting in a decrease in magnetic force that prevents the contact from detecting anything. Based on the analysis, the technical service team examined each factor that could contribute to an increased distance. It was found that the wall thickness of the copper sleeve surrounding the contacts was 2 mm thicker than the normal 5 mm; this increased thickness led to a greater distance between the contacts and the magnet, as well as to difficulties in penetration, which resulted in failures in valve position detection. After the technical service team replaced the sheath, testing results showed normal operation, and thus the fault was resolved, eliminating potential risks to the device’s operation.