From: Kristi Ohr <kohr**At_Symbol_Here**AMHERST.EDU>
Subject: Re: [DCHAS-L] water aspirator - vacuum question
Date: December 4, 2012 12:05:35 PM EST
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: <CAA4EBLvfWs5hw23P=k0-xeZGYOzwHH_42kQTYnR8co6yBpyyfQ**At_Symbol_Here**>

1.  The only thing I've ever used, or seen anyone use, a sink aspirator for is as a vacuum source for aqueous and otherwise non-hazardous (or regulated) materials filtrations (i.e., mostly biology folk).  Otherwise, the use would be inappropriate for all the reasons mentioned by others.

2.  The type of trap you would use depends on what you're doing.  A liquid nitrogen trap is fine for schlenk line work, where you're not really pulling air through something, just more evacuating a small volume.  If you were to use liquid nitrogen for say a filtration, that would be bad because you could condense liquid oxygen.  Dry ice/acetone would be a better option in the case.  If things are aqueous, and otherwise non-volatile and non-hazardous, you can just use a non-cooled trap to protect your vacuum source in the event of overflow.

3.  House vac is fine for filtrations.  For rotovapping, you would likely need a pump for anything with a moderately high boiling point.  The diaphragm pumps are the norm these days for such things, but leave a lot to be desired in terms of performance and robustness.  They're also quite expensive to fix when they do (and they will) break.  For schlenk line work, belt driven pumps are dandy.

From: DCHAS-L Discussion List [dchas-l**At_Symbol_Here**MED..CORNELL.EDU] on behalf of Kim Auletta [kim.auletta**At_Symbol_Here**STONYBROOK.EDU]
Sent: Tuesday, December 04, 2012 8:27 AM
Subject: [DCHAS-L] water aspirator - vacuum question

I need the expert opinion of chemists working with 21st century ideas!

I was in a lab yesterday in Chemistry that is run by a PI older than the hills. His lab is filtering powders and solvents using the sink aspirator. All of the tygon tubing (both sides of vacuum & flasks) is discolored and shows signs of deterioration. They say this tubing is only looking that way because its really old. There was a flask for trap set up between the sample & the sink. I tried to explain that this set up may be allowing solvents to go into the water & down the drain. They tried in their best "I'm the seasoned PhD Chemist and you're not" voices to tell me it was ok and that there was no other way to do this and that everyone, including in industry, does it this way. Really? 

So - my questions to all of you enlightened chemists:
1. Do you still use the sink aspirator/vacuum?
2. If so, what kind of trap do you use to prevent solvent or other hazardous material (liquid & vapor) from going down the drain?
3. If you no longer use this filter/vacuum set up, what do you use?

thanks for your help!

Kim Gates Auletta
Laboratory Safety Specialist
Environmental Health & Safety
Stony Brook University
Stony Brook, NY 11794-6200
FAX: 631-632-9683

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