http://confocal-microscopy-list.275.s1.nabble.com/perfusion-system-tp5674677p5683892.html
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> An appropriate siphon system can provide constant flow for essentially
> unlimited volumes. This is a trick used by old (me) column
> chromotographists, in which a large reservior is connected to the
> column (or small feeding reservior) via a tube that loops lower than
> the bottom of the column (or the perfusion chamber). The pressure is
> determined only by the height of the small reservoir. Flow from the
> small reservior into the chamber causes lower pressure to pull
> solution from the large reservior. If I remember correctly, as long
> as the connecting tube between the reservoirs loops below the outlet
> (waste tube from the chamber) then flow (pressure) is constant. One
> can continue to replenish the large reservoir because there is no
> disturbance of the small one. An added bonus is it can never run dry
> because when the large reservoir empties the flow stops when the
> liquid level in the connecting tube reaches the same level as the
> outlet tube.
>
> If you're interested, I could do a diagram.
>
> c
>
> Carl A. Boswell, Ph.D.
> Molecular and Cellular Biology
> University of Arizona
> 520-954-7053
> FAX 520-621-3709
> ----- Original Message ----- From: "Craig Brideau"
> <
[hidden email]>
> To: <
[hidden email]>
> Sent: Thursday, October 28, 2010 9:03 AM
> Subject: Re: perfusion system
>
>
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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
> <
[hidden email]>wrote:
>
>> *****
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>>
>> 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
>>