[dudeman]

Anyone know a good psi for vacuum distillation ? I'm just curious... I can't find any information online... Would 150 psi do any good?

Dudeman

[csrscience.com]

What?
Am I understanding you correctly, that you are wanting to pressurize it for vac distillation?

The best PSI for vacuum distillation is 0. The lower the pressure, the lower the boiling point of the substance - which means less heat is needed and decreased decomposition/reaction of said substance.

Check these out...
http://en.wikipedia.org/wiki/Vacuum_distillation
http://orgchem.colorado.edu/hndbksupport/dist/distsetup/vacdist.html

[dudeman]

Well this motors made in Germany... Maybe that's why you didn't understand... I'm pretty sure it's sucking at 150 psi... If that's possible? What do you think now?

[csrscience.com]

Ah, I think there is some confusion here.
But you don't want 150PSI in your flasks - this would cause them to burst.

I suppose if it sucks at 150PSI this would make sense.. but I don't know how you would go about calculating the resulting vacuum.

[dudeman]

I guess i will just have to experiment with it... in the future... 

[orgopete]

Check the guage. If it is a vacuum, it won't be 150 psi.

[dudeman]

Well it isn't meant for vacuum distillation. It's meant to for something weird... It sucks and it blows... So if I wanted... I could probably make it create vacuum within distillation system... Just hook up the part that sucks to a tube and then to the receiving flask while making sure that the system is air tight... Would that work? 300 psi shoots a paint ball... if it would put out 150 psi then that should be enough for vacuum right? Am I asking the wrong people? lul

[Borek]

The best PSI for vacuum distillation is 0. The lower the pressure, the lower the boiling point of the substance - which means less heat is needed and decreased decomposition/reaction of said substance.

Not exactly. Amount of heat is the same, but the boiling point is lower, so you can work at lower temp - thus slower decomposition. Enthalpy of evaporation is for most practical purposes not temperature dependent.

[Borek]

I'm pretty sure it's sucking at 150 psi...

If taken literally, that means it will suck only at around 10 atm, and will be completely useless in the normal lab where the ambient pressure is around 1 atm (15 psi)

Something is wrong.