In a message dated 7/8/02 11:40:46 AM Eastern Daylight Time,
[log in to unmask] writes:

<< "would not
 having the cabinet maintained at a slight positive pressure be equally as
 effective except when the cabinet has been opened?". >>

Guess my answer is to go back to the gas laws from our old Physics days.
Water vapor diffuses thru "leaks" about as fast as dry air comes out.  Some
25 years ago, I sold ppm level moisture detectors for a variety of
applications, including dry boxes.  Logic says positive pressure would be
enough, but believe me it "ain't".   The exit of a normal dry box could be
considered a "leak".

Bev - does your dry box discharge thru some kind of dessicant that will stop
the back diffusion of moisture?  That should be more effective than positive
pressure.

A quick look at the following web page can explain some of this:

http://www.terrauniversal.com/products/desiccators/nitrogenpurge.shtml

This just came up first with my browser.

Denny Fritz
MacDermid

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------