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Posted for Ernest Christley <echristl@cisco.com>:
I don't understand the physics of it, all I know is that it worked in another application, and wonder if there might be some crossover. There's always something new to think about, isn't there?
"""
Marv, that sounds like the technique that chemist use to identify substances.
They basically run it though a long, extremely thin tube. The heavier
elements is pulled to the tube walls and slowed down. A detector at the end
of the tube gives an indication of what comes out when, and produces a
'signature' of different chemicals. I would say that water, in the form of
very small droplets vs molecules, either has a hard time getting through a
.010 opening or condenses on the walls before getting through (the glass is
installed with the tube pointing down, right?)
"""
Yes, the open end of the tube is pointed down and hides between the edge of the glass and the glass opening in the sash. Additionally, the path was very long... like 24" of tubing hanging outside the unit and 5-6 feet of it inside the spacer that separates the 2 pieces of glass. I want to stress that I'm not suggesting that we stop using 1/4" AL vent lines on our tanks, but that for overnight parking, the hypodermic tubing approach might be a viable alternative that could stop moisture vapor from getting in. Of course this would add another potential failure mode if the pilot didn't remember to remove the cap from the "real" vent and expected the teeny hypodermic tube to handle the load of fuel movement and varying airspace required inside the tank during flight. As a matter of fact, in retrospect it's probably a really stupid thing to have suggested, although it was hard to share the data point without putting it into some kind of relative (to our purposes) context. Airplanes are definitely not the same as insulated glass units and never the twain shall meet.
<marv>
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