Regarding the selection of temperature measurement equipment?
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During the production process, mercury thermometers are used to accurately measure the temperature involved in the product’s reaction. During customer audits, clients raised concerns regarding the risks associated with the use of mercury thermometers, as there is a possibility that mercury might end up inside the products. Which type of temperature measuring instrument should be used to accurately measure temperature? (The thermometer is used in an acidic medium, where the temperature measured does not exceed 150 degrees. The reaction proceeds at a rapid rate, and temperature control is necessary during the operation; therefore, a thermometer that can quickly determine the actual reaction temperature is required.)
Can a fluorine-lined platinum resistor not be used? What is the medium in your acidic environment? Could a thermometer sleeve be used, made of glass-lined material or 316L steel?
The method used now is a thermometer sleeve; enamel was used in the past, but it didn’t seem to work very well. The reaction process is an esterification reaction, using concentrated sulfuric acid as a catalyst.
This post was last edited and replied to by nglcx2003cn on 2011-6-30 at 17:31. Reply 3# yusea: Enameled steel can be used under concentrated sulfuric acid conditions; what do you mean by the unsatisfactory performance you mentioned? The temperature is 150°C; it seems that fluorinated platinum resistors won’t work either, as the temperature is too high. 316L material also doesn’t work in this case
Reply to 4# nglcx2003cn: The reaction rate is relatively fast. Thermal resistance thermometers were initially used precisely because of their temperature lag, but they are no longer needed. When quality and safety are in conflict, safety is relatively more important. What is used now is a mercury thermometer covered with glass. . . . If mercury thermometers are not to be used, which ones are better?
Reply to 5# yusea: Platinum resistors using special sleeves, such as type HaB, HaC, or those made of tantalum. That price is really extraordinary. What material is your reactor made of?
Reply to 7# yusea: Since you are using a glass-lined reactor, use a glass-lined thermometer sleeve. If you find that the thermometer takes too long to show an increase in temperature, you can fill the sleeve with heat transfer oil; this might improve the situation. In this way, the price is relatively low.
Reply to 8# nglcx2003cn: Okay, thank you for your answer! The company is currently in regular communication with customers to determine which measuring instruments to use. I’ll communicate with you once I have an answer.
Hehe, thanks 8. Why do you always add points to your own posts? Why don’t the moderators add points as well?:lol I hope this post won’t get flagged as meaningless:L
Reply 1# yusea: I’ve encountered delay issues before as well; a thermometer with a glass tube is one of the most practical solutions. It is a systemic issue; everything from the temperature sensor, heat transfer in the protective casing and compensation wires to the display instrument can affect the measurement results. If there is temperature control, it might be more troublesome. Generally, a calibrated mercury thermometer with high precision is kept on site, and its readings are regularly compared with those shown by the instruments. Over time, as more data is collected, it should be possible to create a calibration curve. If the calibration curve is irregular, considering adjustments to the existing temperature measurement and control system may be advisable.