Full disclosure: my experience with peristaltic pumps is limited to
low-viscosity liquids.  Peristaltic pumps will create a pulsatile flow,
which may be important depending on application specifics.  The factors I
see as being most important are the back pressure at the pump outlet and the
inlet pressure from your gas source.  Peristaltic pumps can generate
significant output pressures (depending on the working fluid).  If your gas
source is a pressurized cylinder with a regulator and your pump inlet
pressure is different from the outlet pressure you will have to do a
conversion to find the outlet volumetric flow rate.  But I am not aware of
any thermodynamic reasons why you can't pump a gas with a peristaltic pump,
and your gas selection should only be limited by the type of tubing you use.
 I hope this helps (or at least doesn't cause further confusion).

Best regards,

--
Brian C. Stahl
Graduate Student Researcher
UCSB Materials Research Laboratory
brian.stahl@gmail.com / bstahl@mrl.ucsb.edu
Cell: (805) 748-5839
Office: MRL 3117A


On Sun, Oct 10, 2010 at 2:19 PM, Ned Flanders  wrote:

> OK, I know, this is off-topic, and I will be lucky if my post survives
> the wrath of the list moderators. But still, since I know that there
> are some really smart heads around here, I decided to ask, maybe
> someone would know:
>
> I am trying to achieve low flow rates of some (mostly inert) gases.
> Our flow controllers can achieve the lowest flow of 5 ml/min, which is
> too much for my purpose. We have a bunch of peristatic pumps, that can
> achieve down to a few microliter/min, but they are used, as far as I
> know, with liquids only, because of the compressibility of gases. My
> question is, if I forego precision of flow rate control, could I use a
> peristatic pump to pump a gas? Are there any thermodynamic obstacles,
> and with which gases?
>
> Many friendly thanks in advance
>
> m