Re: Sample pressure

From: Derek (flow@post.queensu.ca)
Date: Mon Oct 29 2001 - 09:06:41 EST


If you want to squeeze your sample into a flow cell with sheath fluid
pushing through it, you will need to use more pressure on your sample to
overcome the sheath pressure - otherwise no sample gets in and no data
comes out.  Simple as that.  A negative pressure differential (sample vs
sheath) would mean that your sample would quickly get diluted out as the
sheath fluid oozes into your carefully prepared sample.  You might
encounter some bright whip who thinks that a venturi effect is enough but
my guess is that you would be running at very slow data rates.

At 05:11 PM 10/25/01 +0200, Marco A. Fernández wrote:

>Dear Flow'ers,
>
>We have started a discussion in our lab regarding sample pressure vs. sheath
>pressure in FACS benchtops (we have a FACScan). I am not sure but I think
>that sample pressure is always over sheath tank pressure (4.5 psi for sheath
>and 4.6 -LO- and 5.0 -HI- for sample). Is that right?
>
>Best regards,
>
>
>Marco A. Fernández
>FACS Facility
>University Hospital Germans Trias i Pujol
>08916 Badalona (Barcelona)
>Spain
>marcoa@ns.hugtip.scs.es
>http://citometria.furebtip.org

Derek Schulze
Flow Cytometry and Confocal Microscopy Facility Manager
Cancer Research Labs
Queen's University
Kingston, ON
Canada



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