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Topic: Rotary pump new….  (Read 5817 times)

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Offline Adamcp898

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Re: Rotary pump new….
« Reply #15 on: April 15, 2014, 09:59:15 AM »

What archer is suggesting is having a cold finger connected along the vacuum line before the pump. The cold finger then is kept immersed in liquid N2 meaning any solvent vapour gets condensed before it gets pulled into the pump.

Do you have regular access to liq. N2?

Indeed I do. Depending on the strength of the pump, ice/salt mix won't be cold enough to condense the vapour before the pump can pull it in so liquid nitrogen is used. You could experiment with mixes of dry ice and organic solvents though to keep things cold.

Offline curiouscat

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Re: Rotary pump new….
« Reply #16 on: April 16, 2014, 02:08:20 AM »

What archer is suggesting is having a cold finger connected along the vacuum line before the pump. The cold finger then is kept immersed in liquid N2 meaning any solvent vapour gets condensed before it gets pulled into the pump.

Do you have regular access to liq. N2?

Indeed I do. Depending on the strength of the pump, ice/salt mix won't be cold enough to condense the vapour before the pump can pull it in so liquid nitrogen is used. You could experiment with mixes of dry ice and organic solvents though to keep things cold.

Sorry, not you, I was wondering if the OP had access.

Offline TheUnassuming

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Re: Rotary pump new….
« Reply #17 on: April 16, 2014, 09:37:45 AM »
I've always just used dry ice baths with acetone or ethanol to cool down my trap.  As long as you clean it out regularly (and aren't being careless) it is sufficiently cold for most applications I have come across.   

OP: If you have a NaOH solution scrubber in line with a high-vac you will just succeed in pulling water into your pump or plugging your cold trap. 
When in doubt, avoid the Stille coupling.

Offline zsinger

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Re: Rotary pump new….
« Reply #18 on: April 16, 2014, 12:42:23 PM »
I do have access to liquid nitrogen, but this sounds like more of a PITA than just biting the bullet now.  Im just going with a science one and am going to create an aspirator which recirculates for now.  DARN those science pumps are expensive!!!!!!!!!!!!!!!!!
                  -Zack
"The answer is of zero significance if one cannot distinctly arrive at said place with an explanation"

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