Seeking help with issues regarding temperature measurement thermocouples.
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With the process conditions remaining unchanged, the temperature measured by the thermocouple decreases slowly in a regular pattern, and then rises rapidly, on a cycle of about four hours. What’s going on here? Please help~
Try another thermocouple; if the same phenomenon occurs, it’s a process issue.
If temperature variation is a concern, focus on checking the temperature changes; or check whether the millivolt value changes during fluctuations
Are there trend charts? It’s easier to make a judgment by looking at the trend chart; if it’s very regular, then the manufacturing process needs to be checked. The most straightforward solution is to replace it with a new one; if the problem goes away after that, then it’s a issue with the thermometer. If there are still fluctuations, then it’s a process issue.
Is there a problem with the thermocouple? Try using another one to see
What’s the temperature? Is it insulated? Is there a leak nearby? When a change occurs, check whether the direct on-site measurement results show the same
Temperature changes are generally slow and occur over a period of time; it doesn’t rise or fall instantly. If the curve changes slowly, it is very likely that the measurement is accurate; such changes are due to variations in temperature under the process conditions. In this case, it is also possible to check the temperature readings at nearby measurement points in the process flow, or use on-site thermometers, or infrared sensors to determine whether the temperature has changed accordingly. If the curve of sudden increases and decreases is similar to a straight line, then it is definitely a problem with the thermocouple or the temperature change; it should by no means follow a periodic pattern.
Hehe. . . What laziness – there’s time to analyze trends and patterns, but no time to go to the site for an inspection. This phenomenon is most likely caused by loose wiring terminals on the thermocouples at the site. I just don’t understand how it’s possible to achieve such accuracy with a cycle time of four hours ?
I replaced the thermocouple and checked, but the situation remains the same. The process condition is as follows: the thermocouple is inserted into a lined pipe, with S4 steam as the medium in the jacket; when this problem occurs, the inner pipe is empty and no material is flowing through it. The steam trap has also been replaced, and there are no issues.
The thermocouple was inserted into a lined pipe, with S4 steam as the medium in the jacket. When problems occurred, the inner tube was empty and there was no flow of medium; the steam trap had also been replaced and showed no issues.
The thermocouple was also replaced once. It doesn’t work.