Author Topic: How to use RTDs at 400-700°C? (Connecting wires)  (Read 692 times)

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Offline jogriTopic starter

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How to use RTDs at 400-700°C? (Connecting wires)
« on: June 20, 2020, 08:53:26 pm »
Hi guys,

i have a question regarding high temperature measurements: I want to measure the temperature of a reaction vessel at different points while it is inside an oven. I choose RTDs because they are rather small and cheap, but i could also use thermocouples.

Now i have a problem: How can i reliably connect the RTDs to wires? I can't solder them as the solder will just melt and twisting the wires together doesn't seem like a great idea either. Looking for RTDs with longer leads isn't an option either as they will be ~40cm deep inside the oven.
 

Online Siwastaja

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Re: How to use RTDs at 400-700°C? (Connecting wires)
« Reply #1 on: June 20, 2020, 08:59:48 pm »
Many options such as high-temperature solder alloys or spot welding, but I think, crimping will be by far the easiest.
 

Offline 2N3055

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Re: How to use RTDs at 400-700°C? (Connecting wires)
« Reply #2 on: June 20, 2020, 10:04:53 pm »
700 C is a lot for RTD, at these temps thermocouples are usually used..
"Just hard work is not enough - it must be applied sensibly."
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Online David Hess

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Re: How to use RTDs at 400-700°C? (Connecting wires)
« Reply #3 on: June 21, 2020, 07:16:32 pm »
Thermocouples would be easier to use at that temperature however at high temperatures, the options are high temperature solder, crimping, and spot welding.
 

Offline wizard69

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Re: How to use RTDs at 400-700°C? (Connecting wires)
« Reply #4 on: June 21, 2020, 07:58:27 pm »
Hi guys,

i have a question regarding high temperature measurements: I want to measure the temperature of a reaction vessel at different points while it is inside an oven. I choose RTDs because they are rather small and cheap, but i could also use thermocouples.
You on the border for proper RTD operation so you might want to look at thermocouples.   Thermocouples are just a welded joint between two different conductors so they are often smaller than RTD's.
Quote
Now i have a problem: How can i reliably connect the RTDs to wires? I can't solder them as the solder will just melt and twisting the wires together doesn't seem like a great idea either. Looking for RTDs with longer leads isn't an option either as they will be ~40cm deep inside the oven.
You can order your leads in any length you want and this applies to both RTD's and thermocouples.   Try companies that are focused on RTD's and thermocouples such as www.omega.com.   We always buy TC's at work that can be hooked up to a load and run through a port on the oven, to a recorder in one run.    It is better to avoid splicing TC to avoid funky connections plus you don't want to accidentally create another junction that offsets you readings.   Omega for example has a check box for 20 meter leads.  Omegas web site seems to be totally screw up at the moment so you may have to call.
 


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