Bimetallic thermometer for temperature measurement
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When a bimetallic thermometer is used for temperature measurement, it is inserted into a sleeve and does not come into direct contact with the medium being measured. So how is temperature determined? Is there any heat-transfer material inside the sleeve? Thank you!
One method of measuring heat is radiation measurement; bimetallic devices determine temperature by means of the heat radiation inside the tube.
OP, simply put, it’s heat radiation heat transfer. If the gap with the sleeve is too large and there is a temperature lag, heat transfer oil can be injected to facilitate rapid heat conduction.
The temperature lags behind and is slightly lower than the actual temperature
The advantage of bimetallic thermometers is their easy installation and intuitive operation. The accuracy is not very high. During installation, the diameter of the sleeve should not be too large, as this will result in a slower response; just make sure to calibrate it using a mercury thermometer.
More precise and faster measurements are required; a substance can be filled inside the catheter – oil can be used when the temperature is not too high, while metal powder can be used at higher temperatures!
To prevent the bimetallic temperature sensing element from being corroded by the medium being measured, a sleeve is used to enclose the element; the element measures the temperature of the medium through heat transfer within this sleeve. Therefore, specific requirements are placed on the size of the sleeve – if it is too large, temperature measurement will be delayed
Some silicone oil can be added to the sleeve, or transformer oil can also be used.
The precision is low… The ones used in our factory, produced by Anhui Sitong, are even worse; the movable error of the universal type gauges can exceed 4 degrees