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Topic: Vacuum Pump?  (Read 3787 times)

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Offline zsinger

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Vacuum Pump?
« on: February 21, 2014, 03:31:05 PM »
Well, Thats all she wrote folks.  My original used vacuum pump is fried beyond all spit and glue, and my mechanic is the cheapest man known to walk the face of the earth.  When he says its done, its assuredly done. 
Anyways, is this an item which is worth biting the bullet and blowing 2k on a diaphragm pump new, or should I seek out used options again?  Ive just never gone through quite such an expensive ordeal.  Any input very much appreciated as always.
                  -Zack
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Offline TheUnassuming

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Re: Vacuum Pump?
« Reply #1 on: February 21, 2014, 04:04:37 PM »
What will you be using it for (rotovap or highvac)?
Diaphragm pumps are great for rotovaps and are super low maintenance but I've never been able to pull low mTorr numbers with them.  If you want to go lower  for high-vac or the like, you need an oil vac-pump.
As far as the new vs used aspect, its more up to you.  Its like anything else you buy used, there is a decreased cost but also increased risk of it crapping out on you. 
When in doubt, avoid the Stille coupling.

Offline zsinger

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Re: Vacuum Pump?
« Reply #2 on: February 21, 2014, 05:10:24 PM »
Preferably both…..my old Ingresol Rand did great for both purposes, but I guess they don't make them like that anymore!  Ill be doing more heavy vacuum rather than rotovap though.
            -Z
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Offline TheUnassuming

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Re: Vacuum Pump?
« Reply #3 on: February 21, 2014, 05:54:15 PM »
You might be able to find a good diaphragm pump that will pull into the low mTorr range but it will probably be quite pricey.  The diaphragm pump I have hooked up to my rotovap is a Buchi V-700 which retails around 3k and it on a good day can only get down to the single digit Torr range. 
You can certainly use an oil vac-pump with a rotovap but you have to be much more careful to not get solvent in it, and they don't like the regular and repeated start/stop of a rotovap system so much. 
If you are on a tight budget used might be the only real option. 
When in doubt, avoid the Stille coupling.

Offline Benzene

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Offline zsinger

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Re: Vacuum Pump?
« Reply #5 on: February 23, 2014, 02:49:13 PM »
Theunassuming,
I am going to consider that pump, as it seems most fitting for my use.  Any do's or don'ts before i blow a wad of cash (this is me crying).
                  -Z
"The answer is of zero significance if one cannot distinctly arrive at said place with an explanation"

Offline Benzene

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Re: Vacuum Pump?
« Reply #6 on: February 23, 2014, 09:24:35 PM »
I use this sort of pump frequently, but sometimes in large scale reactions (20+ Liters of solvent) I have to chain them together. even when chained together, solvents like Methanol and Water take a long time to pull off.
if you are working on laboratory scale, it should be ok.

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