
New glovebox design questions
#21
Posted 07 November 2008 - 01:38 PM
- what's the deal with a "positive" pressure glovebox? how is it used/concept?
I might be imagining it in a counter- productive way..
#22
Posted 07 November 2008 - 02:00 PM
a fan blowing outward will result in a lower pressure inside the chamber than outside (negative pressure) . this will cause new air to be pulled in to equalize the pressure . in most cases , the air will be sucked in through cracks and small openings that would normally not have much air flow . in doing this , a container that would otherwise be considered sealed can become compromised .
a fan blowing inward will cause the pressure to be higher inside , and the air will escape through the same openings mentioned above . this is called positive pressure . if the incoming air is clean (if a filter is used) , positive pressure can be beneficial because the outward flow of air escaping through the cracks can prevent contamination from entering against the current .
#23
Posted 07 November 2008 - 02:25 PM
yes i dig the whole gradient thing
cause without a filter it made pretty much no sense..
have it good
#24
Posted 07 November 2008 - 04:45 PM
I would use a flow hood, but $60 for a kickass glovebox that is equivelently clean is a bit more in my price range than building a $600 flowhood. Not to say that flowhoods aren't nice. They definately are a lot easier to work at, and I still plan on building one when I have the coin to cough up for such luxuries.
I have been looking to build a flowhood soon and my supplies list is around $200
~18" x ~24" x 6" %99.99 HEPA filter ~$100
Used squirrel cage fan Free at your local HVAC company
110V 3 speed motor to replace the big ass one in the fan ~$50
4' x 8' sheet of good quality oak plywood ~$35
Screws, paint, silicone ~$15
I'll be sure to post a rundown of it when I build it, hopefully before xmas
Sorry, off topic but I thought y'all might like to know
#25
Posted 07 November 2008 - 07:55 PM
I have been looking to build a flowhood soon and my supplies list is around $200
~18" x ~24" x 6" %99.99 HEPA filter ~$100
Used squirrel cage fan Free at your local HVAC company
110V 3 speed motor to replace the big ass one in the fan ~$50
4' x 8' sheet of good quality oak plywood ~$35
Screws, paint, silicone ~$15
I'll be sure to post a rundown of it when I build it, hopefully before xmas
Sorry, off topic but I thought y'all might like to know
I have looked into this before. The problem I keep running into is lack of finding the "Used squirrel cage fan Free at your local HVAC company"
I have resorted to trying "Cheap squirrel cage fan" on Craigslist and Ebay. I check back periodically, but still haven't found anything that is both cheap (<=$100) and up to the task (>=600 CFM).
If you have any advice about the Free fans, shoot me a PM. I would love to know where to get one.
Blessings,
Oakchild
8-)