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K-type hightemp and corrosion resistant thermocouple-but how to attach it?

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Hydron:
Haha, I was going to post "just be lazy and butcher one of the cheap ones that came with the Uni-T" but was too slow and you've done just that :-DMM

For the best accuracy just try and avoid temperature gradients across the connection points (incase the metal of the plates are not correct for type K).

Leland_Gaunt:
hi, i just wanted to give an update that might help some people with the same hobbies i am..i built myself a probe now for 7 bucks and its the best thermometer i ever had. I just bought a k-type wire in glasfibre-fabric, rated for 480 C. (5 bucks) and put it into a cheap 1ml-Glaspipette. (2 bucks). The open tip can easily be closed by melting, you dont even need a bunseburner, a good storm-lighter with a pointy, blue flame is enough. 500C is about the maximum this glas should handle, so the 2 parts fit together pretty well. Its made for very acidic or alkaline fluids anyway and the hottest i can think of is hot sulfuric acid that gets slightly over 300 C. hot when you concentrate it.

The corundum-thermocouple had 2 flaws, first its very thick, it doesnt even fit through a regular thermometer-Glasadapter, because its slightly thicker than 8mm. Its also very slow responding, while the glas-thing has a good reacting time, once you rub your fingers on the tip, it only takes a few seconds and the temp. starts rising.

rogerggbr:
Excellent solution. As an ex-'tiffy (Instrument Artificer) I would always suggest just using the appropriate compensating cable (extension cable) for the whole thing, protecting the end as required, exactly as you have. Type K is tricky sometimes as there are 3 different types available, some more popular than others (KX, KCA, KCB). For my use I prefer type T (<300C), in my previous life we always used type J (<500C), both readily available.

Kleinstein:
The compensating cables are just a cheaper alternative for a limited temperature range. Using the TC wire pair all the way to the connector / cold junction is perfectly fine, just possibly a little more expensive when the wire is long.

The thermal contact inside the glass tube can be a bit tricky and may not be that good. It may help to have the TC wire(s) slightly coiled inside the glass to get a bit better contact and bit more thermal resistance for the wire part.

One can usually get plain glass tubing by the meter rather cheap. It still depends if there is a shop as shipping could be expensive.
Shops with chemistry glass ware usually also tend to have just tubes to bend as needed.

Leland_Gaunt:
you dont need a good contact inside. Its just a very small capillar with maybe 2mm diameter, the air inside will take the temperature of the glas in a matter of a few seconds. A very tight diameter that fits the thermocouple perfectly would just make for a even better response time. Not that important for me- The 0.5ml Pipette does have an even smaller diameter. Its just i only had the 1ml at hand.


i didnt use any extension. Just the 1m probe "SMPW- GG-K-30-SLE" from AliExpress. Dont know how accurate it is. But will be more than enough for me.

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