Chris Hodges wrote:
N. Thornton wrote:
Indeed.
And only need a couple of holes drilled and pumped through with CO2
to make them clear again.


why CO2 tho? Plain air works I believe.

Plain _dry_ air would, but it's probably easier (==cheaper) to get hold
of CO2 than dry (enough) air.

CO2 is almost as good (or slightly better, I can't remember) than Argon.

Heat conduction in a gas is dependant on the molecular weight.
N2 is 18, O2 is 16, and CO2 is 48.
I think Ar is 45, though I'm pulling that from dodgy memory.

I suspect argon is used instead of CO2, as CO2 may react slowly with
the aluminium along with trace moisture.

Butane would be even better, with a molecular weight of 58, but has
some obvious problems

You could fairly easily get the air dry enough.
Take a large block of ice, thread some tubing through it, put it in
the freezer, then blow air (slowly) through the tubing.
Most of the moisture will freeze out on the walls.
Good enough for double glazing anyway.