Sciencemadness Discussion Board

Which is the better pump?

chemchemical - 13-2-2010 at 16:05

I bought a vacuum pump not too long ago and just recently I came across a pump that was being thrown out.

the one I bought is a Precision Vacuum Pump model DD50 (I think, it had the motor model and all that.) These are the specs I found for it:
Free Air Displacement 50LPM
Ultimate Vacuum 0.5uHg
Motor Capacitor Start 1/4HP, 1725 RPM
Oil Capacity 1 1/4Qt
Intake Size 3/4"
Dimensions W X D X H 7" X 17" X 113/4"

The pump I found is an Alcatel 2008A, I know these are a good brand but I dont think it has the same ultimate pressure. Someone was just throwing it out, it looks new and I know these things cost a ton. Its specs:
Model 2008A
Pumping Speed Nitrogen 6.0 CFM (170.6 l/m)
Ultimate Pressure 1.00E-2(En) torr (1.33E-2 mbar)


What do I want to look for when choosing a pump? I would like to use it for distillations and pulling solvent off pure products. I assume I want the lowest ultimate pressure for pulling residual solvent off, but if I'm doing distillations then its not that important because I wont be using it that low (its possible to get a gauge and control the vaccum, right?) Should I be looking at the air displacement? What about the horsepower? This will just be for small projects, I dont plan on running it continuously or for more than a day.

Also, does anyone have suggestions for controlling the vacuum pressure for doing distillations or anything that requires less vacuum than the ultimate?
I would also like to get rid of one of the pumps, preferably the precision because its older and I just think the Alcatel is better.
Any info on the pumps and which one you would keep and why is appreciated. Also, anything on what the different specs mean would be nice too. I think I paid around 150-200 for the precision pump.

chemrox - 13-2-2010 at 20:21

They both like good pumps. I would not get rid of the alcatel. Mine pulls the vacuum you indicated with little tweaking of the lines. I'm a packrat. A second good pump would be stored or used to drive another vacuum apparatus

chemchemical - 14-2-2010 at 14:24

Yes, I would like to keep both but at the moment I could use the space and money, plus I dont really need two high powered vacuums for my situation.

I was thinking the Alcatel was a better pump, I would still like a way to be able to control the pressure to do distillations and to hook up to my rotavap.