This is news to me. How do you know this? What rate of transport are
you thinking of? Sufficient pressure can rupture the material. I
guess that will send liquid water through Gore Tex. That will depend
on the material's strength, thickness and size of unsupported area,
assuming it is backed up by some sort of mesh or perforated material.
What little I know about these permeable fabrics is that the holes are
so small that water droplets won't fit through but water vapor-
individual molecules- will. So water transport will be a combination
of permeation through the body of the Gore Tex (extremely small but
probably measureable with the right instrumentation) plus difusion
through the holes in the material.
Water droplets or macro amounts of water will have an equilibrium
pressure of water vapor in the vicinity of the surface. This is
dependent on temperature not pressure. If water is in contact with
Gore Tex I suppose the holes will be exposed to the equilibrium vapor
pressure of water and difusion will occur. I don't see how
pressurizing the water will increase this rate significantly.
Are you thinking of capillary flow? You can think how much pressure
would force measureable capillary flow through the micro holes in Gore
Tex. How could you prevent material failure at the very large pressure
this would require if it is possible at all? Is this an opportunity
for me to learn something new?
It's certainly an interesting topic.
Richard, yes, this is an opportunity for you to learn something new, or
learn something decades old, as the case may be.
There is a test called "water entry pressure" or something similar.
It is used for various kinds of "waterproof" fabrics. Including regular
Sometimes it is expressed as the height of a water column needed to
cause water to extrude through the micropores.
I had a Helley Hansen jacket rated at 20,000 mm.
If you look at the Columbia line of "waterproof and breathable" garmets,
there is often a hang tag which lists both a water entry pressure number
and a number that represents a "water vapor permeability" number.
There are different tests advocated by different people for the same
thing, and there appears to yet be no US standard widely used in
Google is your friend for enlightenment.
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