Quote: Originally posted by draculic acid69 | Quote: Originally posted by monolithic | Quote: Originally posted by draculic acid69 | Tried boiling a flask full of water.mantle still gets to 300~ish degrees'c even when dial is set to 100.it appears that the temperature probe isn't
more than 2 degrees off when it comes to boiling water.dont have a higher boiling liquid available ATM. Did figure out my glass thermometer is a lil
bit off.reads 108 in boiling water but the mantles 2-300'c spikes make it useless for anything other than boiling water.theres not one rxn I can do
that wouldn't be ruined by this kind of overheating.the knob doesn't seem to make a difference which ever way it's turned.this thing as it is is no
better than those 2000w hotplates from kmart.i might just rip the guts out and put a Pwm thyristor circuit in there like my other one which is working
fine. |
Temperature controlled hot plates and mantles don't regulate the voltage to the heating element. It's expected that the mantle is going to hit 300 C
or whatever its maximum output is. Put the probe in a flask of water, completely ignore the temperature of the heating element, and set the
temperature of the mantle to something below boiling, like 70 C. Does it eventually stabilize at 70 C? Then it is working as it should. If the probe
is off by 8 C then I don't think there's much you can do as there doesn't seem a way to adjust the calibration. You can buy PID controllers pretty
cheap ($50 or less on Amazon or eBay) that offer a ton of configuration: support for different types of thermocouples/thermistors, support for K/F/C
units of temperature, calibration adjustment, etc. It wouldn't be much work to wire one up to an SSR or mechanical relay, to control a hot plate.
If you're looking for something to control the temperature output at the heating element, you need something like a soft heating mantle (Glas-Col or a
knockoff) plugged into an AC transformer (Variac or a knockoff), set atop a magnetic stirrer or magnetic hot plate/stirrer with the heating circuit
turned off.
[Edited on 11-2-2019 by monolithic] |
Imagine your doing a 100ml size grignard and you set the temperature control to 60'c
and then within a minute it's boiling and then it's out of control spewing out of the flask bcoz this 'operating as it should' mantle heated up to
over 250'c within a minute
(gets hot quick) other than boiling water that kind of temperature difference has the potential to ruin rxn's.
[Edited on 2-11-2019 by draculic acid69] |
monolithic is right, you can't expect everything to work the way you think it should in your brain. A heating mantle designed the way you think it
should work would be useless, imagine wanting to boil some water and your mantle only heats to 100C. Your water is never going to boil.
Your "hypothetical" situation is like saying, this masonry drill doesn't work well when I try to use it for dentistry, it just destroyed my patient's
entire mouth. They should have finer speed control on it. It's not the problem with the equipment, but with the way you're using it.
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