Best Thermocouple Adapter for SPD

The notorious leaky thermo-couple… Which ones do you prefer?

None, use the inboard thermocouple on the mantle.

A thermal well , with some vac oil in it a ml or 2 to facilitate heat transfer.

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What mantle do you have that allows you to do this? I’m restricted to an external controller dependent on the thermo probe. :frowning:

I just fought a massive leak that blew up all of a sudden mid run. I fixed it by wrapping sealing tape around the top and bottom of the cap, once i isolated the issue. Then it steadied out at 1700 and i was leak free after that. Fucked up my bf a bit, splashed the walls so i couldn’t see what was gong on in there that easy.

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If you have a Chinese mantle it should have come with a cap that will plug into the port which the probe connects to. If the cap is inserted it reads the internal probe.

Supposed to be American made, from lab society. So i could essentially get rid of this critical issue by going standard Chinese and remove one thermo, maybe both seeing that summits new head seems to lack a thermo probe from the pics I’ve seen.

Ahh, referring to the head probe? You will want a thermowell adapter, it’s a ground glass joint with a tubeulation for your thermometer. It will seal better than a shit o ring. I don’t understand why lab socitey wouldn’t include a thermo well.

The head probe for summits new head, yes. I’m trying to shorten the path as much as i can with as few connections as possible. The parts i got for my setup made it long path and not so effective.

There is a lot of things that are hard to understand with the way they set things up.

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Aaah, so that’s why you need to know your stirbar real well when using them in the bf. But ok, thank you very much for this info. I was trying to find this as a normal adaptor. My initial search for thermo well yielded some metal thing, i didn’t get what it was until just now.

I don’t like probe in the boiling flask because of the temp difference between the heater temp and the probe temp. By the time the probe tells the heat to stop the outside of the flask is overheated. This is how people are killing stir bars and mantles through degaussing of the magnets by taking them to their curie temperature. Imagine a pot of boiling water, water will only boil at 100c, no matter how much energy you drive into the water. The water will only allow so much energy. Imagine a situation where it takes 100 energy units to boil a solution, the solution is controlled by a probe in the liquid. The heater starts by dumping 200 units of heat into the liquid, then the probe sees 100 and says stop. Then the probe seeing the liquid cool one degree says “give me another 200 until I say stop”. This can also contribute to pid overshoot.
Do you see the problem?


I’m learning this the hard way. Thank you very much for the info.

Certainly, and I have seen this issue with mantles in the past. However our Heidolph hot plate seems to do a great job at never over-heating. Have run it for almost 2 years through hundreds of batches.

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So I’m wondering whether putting the cap in my probe after having used the mantle for well over a year with the thermometer in the BF is going to cause even more PID overshoot issues …

I’m pretty certain I’m leaking at my o-ring given the large amount of condensation in my cold trap … and I’ve contacted my glass blower about getting a thermowell … or one of the new Summit/LS style ones which just has more support below the joint but isn’t actually a well … but I’m curious now, as capping the mantle port is an option I was aware of, but hadn’t ever considered.

Either way, the shitty chemglass O-ring has to go. So …

Thermowell with a bit of silicone oil inside it for heat transfer …
Thermowell with the end cut off (Summit/LS style) …
Or cap the mantle? (Even though I’ve been using it with the probe since day 1)

Have you tried wrapping the cap with high pressure gas sealing tape? Put it on both top and bottom of the cap, so the entire thing is technically sealed from the outside?

I had a massive o-ring leak blow up on me last run and i saved it by doing the above. Ran the entire process without further issues.

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Keep going if that works for you. As an experiment next run place a temp probe on the mantle surace under the rbf . Use a data logger and compare it to your mantles logger. Check out how the two curves compare.

Hmm interesting…My joanlab heating mantle only has 1 temp sensor and that is the external thermometer (at least that i saw when I removed the bottom panel only 2 wires for the heating element and 2 wires for the magnet stir motor, no temp probe or unknown wires in sight) and my current bf has a thermo well in it, which makes me nervous to use a stir bar, as I used once and kept hearing it ‘clank’ into the well over and over and it just degaussed…but I am overshooting temps often and was thinking of buying a 2 neck flask with a thermo adapter to have more accurate temps getting the thermometer out of the well and using a stir bar, but I will mention I was not using oil in the well… should I be looking into just a better heating mantle instead?

You absolutely need something to conduct the heat to the probe. Without it your mantle is a blind man in a dark room! Placing the temp sensor inside glassware will allow your mantle to overshoot, this is because the glass is slow to transfer heat. Imagine trying to cook a turkey for dinner. You place the cold bird into your oven with the probe in the frozen center of the turkey.
Now when you press go on your oven it will basically go into clean mode until it feels the thermocouple say ok, we hit 165 degrees! Blackened turkey anyone?

If my comment is out of line, kindly delete it…

All of the heating mantels including Glascol and Heildolph have issues with overshooting set points, The Heildolph is especially puzzling. What’s the benefit of having the thermocouple placed on the outside of the boiling flask to control solution set points? Even if the temperature probe is placed in the solution overshoot occurs, especially when the stir bar dislodges.

CAT in Germany manufactures the best hotplate stirrers in the world for solution set point control. Take a look at what Skunk Pharm Research has to say, MCS66 Hotplate Stirrer Test

We’ve made several offers to have our hotplate stirrers tested by Lab Society, Extractor Depot, Scientific Solutions, Summit Research, etc. all told us to get lost, contempt prior to investigation! If you want to experience what’s it’s like to have a device that actually works for solution set point control, then you should consider getting a CAT hotplate stirrer. And yes, you can actually place the thermocouple in the solution.


I’m degaussing my stirbars almost every run. If you remember I was having heat and vacuum issues. I have since addressed them and am getting much better results (< 300micron during main body &no red after 2nd pass). Do you think my stirbars will last longer with lower heat? To remagnatize I can just store them with other, charged magnets?

Thnks!!! :pray:t4:

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