From: Ken Simolo <simolo**At_Symbol_Here**CHEM.CHEM.ROCHESTER.EDU>
Subject: Re: [DCHAS-L] water aspirator - vacuum question
Date: December 5, 2012 8:14:48 AM EST
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: <7E7CECFB20453648A1D32729449F7388059026B2**At_Symbol_Here**>

On Dec 4, 2012, at 12:05 PM, Kristi Ohr wrote:

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.

Not everyone's experience has been the same as this.  We have been extremely pleased in the use of diaphragm pumps for rotary evaporation.  We have been using KNF diaphragm pumps on rotovaps for over 8 years with only 1unit out of over 30 requiring a head rebuild (they abused the pump by literally pumping liquids and solids through it).  It was not that bad of a repair either.  I heavily researched which brand to get.  At the time when i called various pharmaceutical companies, I found out that some brands were requiring rebuilds every 1 -2 years but KNF was lasting 7 or more.  We have been extremely grateful that Steve Schifferle at Harvey Instruments had strongly recommended that we look into these pumps and to call the pharma companies to see what their real life experience was like.


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