peace c - 5-5-2005 at 03:08
Hi Guys,
I am close to buying a hplate/stirrer but have questions with temp control. The hp/stirrer I am looking at contolls temp in 1deg increments. Is this
really necessary. For instance say if one wanted to distill at 138deg a hp/stirrer that is incremented in 5deg lots wont hit this exact temp. Does
this matter? Will it still do the job efficiently or will one suffer from forerun etc as other stuff comes over?
The brand i am looking at is manufactured in Taiwan by Today Instruments. Anybody have any experience with their products?
best wishes,
peace c
neutrino - 5-5-2005 at 12:59
For most operations, you really don't need any temperature control. I use mine on one two settings: HIGH (full power) and 3 (about 1/2 power). If
you want to distill something, you don’t need tight temperature control. Say you wanted to distill water. Anything from a 100*C heat source to a gas
flame (>1000*C) will make it boil at the same temperature.
There are, however, some operations where precise temperature control is necessary, i.e. some reactions that are temperature-sensitive. In most cases,
though, this can be improvised with a water bath. For example, say that you need a 68*C bath. Heat water to this temperature with a heat source and
disconnect the source. When it cools a little, turn the source back on. If you’re doing this where your time is important, however, (in a
professional lab) you might want an automated device.
adroit_synth
adroit_synth - 10-5-2005 at 10:37
For distillation I have an old deep fryer with a temp control dial that reaches 450F and works rather well. Of course when a vacuum is added,
much higher boiling points can be achieved.
Oil selection matters.
I submerge the RBF about 2/3. This speeds fractional distillation as it keeps the gas in the top of the flask hot as well.
Rosco Bodine - 10-5-2005 at 11:21
I can tell you from having and using both types , that the thermostatically controlled
heating is by far superior . The truth is that any lab grade equipment should have
instrument quality narrow range accurate
thermostatic control . And it is simply cheap corner cutting when rate type controllers are used instead of what should be used on a laboratory tool
where
frankly the electrical and safety codes should make it mandatory .
peace c - 12-5-2005 at 02:09
I agree Rosco. Not only cheap but also dangerous. For a few hundred bucks extra i can sleep easy at night.