Vacuum Pumping Update

From: Brad James (bjames@exponent.com-DeleteThis)
Date: Thu Feb 11 1999 - 15:41:52 PST


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From: Brad James <bjames@exponent.com-DeleteThis>
To: "'wind_talk@opus.hpl.hp.com-DeleteThis'" <wind_talk@opus.hpl.hp.com-DeleteThis>
Subject: Vacuum Pumping Update
Date: Thu, 11 Feb 1999 15:41:52 -0800
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Thought I'd give you guys/gals an update on how my vacuum pumping project is
going, and ask for some help/insight.

The good news is that I've got the vacuum system dialed. I can get whatever
pressure I want, and run my pump for a long time, and have never had a
problem with any of the boards I've worked on.

My problem is that I've discovered that I need to be at a higher than
winter-time garage temperature to get more efficient boiling of the water
out of the board. Consulting the steam tables indicates I'd need to be at
about 160F to get full on boiling of the water, and easy sucking out the
board. However, I don't think it needs to get that hot to work. The only
other vacuum pumper I know (the "board lady" from Ventura featured in
Windtracks)uses a furnace to heat her boards to about 110 - 120F to get all
the water out.

I've tried electric blankets inside regular blankets and a padded board-bag
for insulation, which doesn't get hot enough. I looked at buying some
heating cable and a controller, and may still do it, but that's almost $200
- plus I'm no EE so I'm a little leery of wiring all that up.

Do any of you electrical engineer-types have any good ideas? The criteria
are that it has to be fairly small to fit in my small garage, and safe
enough that I don't burn my house down or have my toddler get shocked or
burnt. Not that I'm going to be charging anyone for this service for quite
a while (or maybe ever, for that matter), but if someone can help me out
with this, I'd give you free water removal for as long as I do it!

Thanks

Brad

ps. I know I can wait till summer and heat the board in a car or on my
driveway to the temps I need. But that doesn't help all the guys who are
waiting for me to suck the water out of their boards before the season
starts!



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