Re: [APML] The Veil...

[steve banbury <banburys@sonic.net>]

FWIW, after reading Philip Perkins post the other day I dropped by a local
welding shop 
to price a nitrogen purge system.

The smallest high pressure tank (~2000 psi) for nitrogen was 20 cubic feet,
and
cost $85. 
Refills are $15.
Regulator, gauge and hose were another $85. 

A small needle valve to get really low flow rates runs about $16 from a place
like 
<http://store.yahoo.com/valvestore/n2pneutbrasn.html---welding>http://store
.yahoo.com/valvestore/n2pneutbrasn.html---welding shops don't carry them.

I haven't located a vendor for the flow meter that Philip uses, but I bet
they're not cheap!

Philip's page shows a significant benefit in performing a nitrogen purge
versus
no purge
although it doesn't mention which film was used.  Unfortunately there's no
comparison of
results with dry air only purging.  Probably some films benefit more than
others from using 
a nitrogen purge.

If anybody has some comparisons of the results from the 2 processes, I'd be
interested in 
seeing them.

Steve


At 11:53 AM 5/30/03 -0400, John Boudreau wrote:
snip

>BTW--- A dry air or nitrogen purge is still a good idea in damp conditions. I
use a dry air purge based on Herm's system. But I doubt it would have made a
noticable difference in these shots.
>

_______________________________________________
Astro-Photo mailing list
Astro-Photo@seds.org
http://seds.org/mailman/listinfo/astro-photo