Sciencemadness Discussion Board

Recommended thermocouple and well adapter?

thors.lab - 28-8-2020 at 07:01

I'm looking to upgrade to a thermocouple since I don't really trust the cheapo rubber gasket thermometer adapter on my still head, especially for vacuum distillations which I plan to get into in the future. Can anybody recommend a particular thermocouple from amazon?

Additionally, I'll need a 24/40 well. There seems to be a couple different types: one with some sort of sealing gasket and is intended to be filled with some sort of conductive fluid:
Quote:

It is basically a long glass tube which is sealed on one end and partially filled with a fluid to transfer heat such as mineral oil.


That tends to be super expensive — like $80. And then theres those that's literally just a long tube. What's recommended here? Is the thermal insulation really necessary? What should I use for heat transfer (if anything at all?)

This one's just a tube. Is that good? Says this is for 2 neck flasks. Is there any reason this also wouldn't work on a still head?

Finally, I'm looking to upgrade to a heating mantle stirrer. Any amazon/ebay recommendations sub $200? There some options on Amazon, but I'm kind of sketched out about how low the price is (only $80??). Are there any reasonably priced mantles out there that I can control digitally? If so, I could program up a PID, hook that up to my thermocouple, and have some sort of closed feedback. That would be pretty sick.

Edit: Can anybody attest to this? $150 for a digitally controlled mantle with feedback. Could I pop that temp probe onto my still head for controlled distillations?

Thanks,

Thor

[Edited on 28-8-2020 by thors.lab]

[Edited on 28-8-2020 by thors.lab]

macckone - 28-8-2020 at 10:10

I got my thermometer well from rocco glassworks (now at rocco scientific)

https://roccoscientific.com/product/thermowell-24-40/

The cheap ones are fine but better ones will withstand higher temp differential.
Glass stress is less of a problem because of the narrow tube as opposed to a large flask.

As for fluid, mineral oil is good enough for temps 300C or so (depends on the mineral oil).

Ethylene glycol is good up to 170C (it boils at 197C).

Vegetable oil is good up to the smoke point.
Peanut oil = 232C (450F)
Advocado oil = 271C (520F)
Canola Oil (and many others) = 204C (400F)

I would not go over 300C if I could avoid it.

Finally on the heating mantle, Faithful and a lot of the others seem to be exactly the same design with different names stamped on them. The quality is 'cheap' but it isn't going to set you back $500. The level of control with the manually operated ones is 'not the best', the one with the digital control is going to be better.
The built in control may not work well with a thermowell on the cheap digitals.
I have heard complaints even on the expensive ones as it changes the PID parameters and they aren't usually adjustable.

With a thermometer well, any thermocouple of the right type should work (usually k type with DIN connector).
See my above comment on the change in PID parameters.

draculic acid69 - 6-9-2020 at 06:24

Quote: Originally posted by thors.lab  
I'm looking to

That tends to be super expensive — like $80. And then theres those that's literally just a long tube. What's recommended here? Is the thermal insulation really necessary? What should I use for heat transfer (if anything at all?)

[url=https://www.ebay.com/itm/All-glass-thermometer-adapter-24-40-100mm-s

Edit: Can anybody attest to this? $150 for a digitally controlled mantle with feedback. Could I pop that temp probe onto my still head for controlled distillations?

Thanks,

Thor

[Edited on 28-8-2020 by thors.lab]

[Edited on 28-8-2020 by thors.lab]



Yes I can attest to the pictured digitally controlled heating mantle and I can state :
DO NOT BUY.THEY SUCK.DOES NOT WORK AS ADVERTISED.. OVERHEATING WILL HAPPEN.DO NOT Setting the temperature does nothing.to keep either the rxn or the mantle at the set temp and then even with the temp set the mantle heats up to 300+ degrees at least.mine clicked on and off the same way those $30 Walmart/Kmart hotplates do.zero ability to achieve the desired temperature.waste of $350+..mine was all in Chinese writing and didn't come with instructions.absolutely useless piece of equipment
mine is lying open with the guts ripped out to be replaced with a reliable $4 2000w 240v variable motor speed controller:https://www.ebay.com.au/i/333672583248?chn=ps&norover=1&mkevt=1&mkrid=705-139619-5960-0&mkcid=2&itemid=333672583248& ;targetid=921460872233&device=m&mktype=&googleloc=9068943&poi=&campaignid=10892897993&mkgroupid=107582961032&rlsatarget=pl a-921460872233&abcId=9300398&merchantid=7364522&gclid=EAIaIQobChMI0OSm1NvU6wIVUw4rCh3pGgJ1EAQYASABEgJoKvD_BwE

These are a $10 Variac substitute that works excellently unlike the shitty unreliable stuff it came with

draculic acid69 - 6-9-2020 at 06:27

Another thing that happened was I set the temp let it heat up then adjust the temp dials to a lower temperature and the thing decided now was a perfect time to continue heating