RE: filters

[Franz Schoenhofer <schoenho@via.at>]

At 15:35 15.11.1999 -0600, you wrote:
>Activated charcoal traps radon (that's what they use for detection in radon
>in air surveys) and passes water. 

No! Water is also adsorbed by activated charcoal. This is the reason why in
the radon detector vials which I use since many years for radon-in-air
determination by liquid scintillation spectrometry a desiccant is mixed to
the activated charcoal. The desiccant is silicagel and prevents the
clogging of the activated charcoal by water. Therefore silicagel would be a
substance to remove water from air and let the radon pass through.



Water charcoal filters used on ground
>water will trap lots of radon - just stick a micro R meter on one and see!

Water charcoal filters have excellent properties to remove radon from
water, but they remove also the daughter products and they keep the
daughter products from radon decay adsorbed. This is the reason why such
filter columns show elevated gamma doserates - radon-222 is an
alpha-emitter.....


>
>Cold traps will remove most water vapor but I don't know how much radon may
>come down with the water vapor - I suspect not too much.

Radon has a boiling point of -60 centrigrades. You can imagine what happens
with radon in a cold trap with liquid nitrogen.... An ice bath would on the
other side not be very effective for water vapor.


Franz


Franz Schoenhofer
Habicherg. 31/7
A-1160 Vienna
Austria
Tel.: +43-1-495 53 08
Fax.: same number
mobile phone: +43-664-338 0 333
e-mail: schoenho@via.at

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