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A few years ago one of our students needed non-pulsing flow for a perfusion
setup.  As an added catch, the perfusion had to run for over 20 hours, so
syringe pumps didn't have sufficient volume.  I managed to find a very tiny
gear pump that provided steadier flow and had enough head to feed from a
fairly deep reservoir jug.  Gear pumps basically trap small amounts of fluid
between the teeth of a pair of gears.  The flow from the pump is still
slightly pulsing but much better than a peristaltic pump.  The pump has been
used for a number of different projects over the years and is still working
well.

Craig


On Thu, Oct 28, 2010 at 1:14 AM, Jeremy Adler <[log in to unmask]>wrote:

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> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> The cyclical pressure changes produced by roller pumps will cause movement
> of the chamber and a change in focus.
> This can be eliminated by (a) using a air filled side arm which damps the
> pulsations, as a been mentioned previously, and (b) by making the outlet
> port of the perfusion chamber much wider than the inlet port - something
> rarely seen in commercial perfusions.
>
> Gravity provides pulseless driving force for perfusions and is quite cheap.
>
> Jeremy Adler
> Genetics & Pathology
> Rudbeckslaboratoriet
> Daghammersköljdsväg 20
> 751 85 Uppsala
> Sweden
>
> 0046 (0)18 471 4607
>