Re: Air absorbtion by charcoal.

edson wrote:

Uncle Al wrote:

You'll get some slow hysteresis from adsorption and desorption.
Wouldn't it make more sense to install a pneumatic dashpot (e.g.,
slowed bellows)?


I appreciate the info'
I would like to know the mechanism of absorbtion. Do the gas molecuses
bind to the charcoal thus reducing the volume of gas? How slow is the
hysteresis? Is it seconds or milliseconds for a step change of 2-3 psi?

Most of it is physisorption - weak forces like those that create
capillary action. Oxygen is a triplet biradical and paramagnetic.
Charcoal has all that pi electron density plus unpaired spins of its
own. That gives you some chemisorption.

The total differential adsorption for a 5 psi pressure swing is of
academic interest only. Hysteresis from gas viscosity in a fine-pore
medium will be enormously greater - and still small for a 5 psi
pressure swing. Handle it mechanically, the way a parallel capacitor
smooths the output of a full wave rectifier bridge.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz3.pdf
.

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