Temperature measurement using a bimetallic thermometer, hurry up!
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We use bimetallic thermometers to measure the gas temperature; they have a protective sleeve, and the temperature usually ranges from 10 to 25 degrees. Due to the presence of this sleeve, the measurements are not accurate – there is an error of about 5 degrees compared to those obtained with transmitters. To address this error, can we add some substance such as oil inside the sleeve? What oil should I add? Will this solve the problem? Thank you, I hope an expert can answer.
Bimetallic thermometers already have a relatively large degree of error; the error is even greater when measuring low temperatures. The lag caused by the sleeve can be reduced by adding fluid – transformer oil will work. It’s best to use metal powder, with copper powder being a common choice (you can simply grind some yourself)
OP, generally thermal oil is added, but the bubbles need to be removed. If there is no heat transfer oil, lubricating oil can be used as well since the temperature is not high.
Reply to 3# king70868: Thank you
We use glycerin, as well as silicone oil; heat transfer oil works too
The error of bimetallic thermometers is inherently greater than that of transmitters; it is necessary to perform calibration and apply correction values before making a judgment. It’s not a matter of adding oil to the casing – generally, thermal resistors and thermocouples also come with casings, and there is no requirement to add oil to them~~~
Changing the diameter of the temperature sensor tip can also solve this problem
Adding some copper powder to it increases the cost a bit, as copper has good thermal conductivity.
Even with two additional sleeves, a difference of 5° should not occur; a difference of 2° within 100° is already unacceptable. It is recommended that you first conduct a thorough inspection, checking things such as the zero point of temperature variation, the connection points of wires and connectors, as well as the pointer of the on-site thermometer, among other factors
Why use a bimetallic thermometer? ? Just use a regular metal-tube mercury thermometer!
I wonder, since a bimetallic sleeve is used, why isn’t a thermal resistor used as well?