Fume Hood Window

[Noxx]

Hey,


I'm designing a fume hood which will be 5 or 6 feet long. Now, I decided to use Lexan (polycarbonate) instead of acrylic. I can get 4'x8' sheets of a thickness of 1/8'' and 1/4''.

They are $171 & $313 respectively. What would be best for my application ? I don't want to sheet to flex due to negative pressure.

I know that Polycarbonate is sometimes not recommended but how well does it resist to non-solvent chemicals ?


Thank you

 

[Geo]

from wiki. hope it helps.

Polycarbonates, known by the trademarked names Lexan, Makrolon, Makroclear and others, are a particular group of thermoplastic polymers. They are easily worked, moulded, and thermoformed. Because of these properties, polycarbonates find many applications. Polycarbonates do not have a unique plastic identification code and are identified as Other, 7.

Chemical Resistance
Acids – concentrated Poor
Acids – dilute Good
Alcohols Good
Alkalis Good-Poor
Aromatic hydrocarbons Poor
Greases & Oils Good-fair
Halogenated Hydrocarbons Good-poor
Halogens Poor
Ketones Poor

 

[4metals]

One way to get away with the thinnest (and cheapest) sheet is to contact cement it to a sheet of plywood. Just build it of plywood with the inner sides of the thin sheet goods.

sorry just saw the subject "fume hood window" loose the plywood backing idea.

 

[Harold_V]

The loading on that surface area, even with just a half pound pressure difference, is going to be severe. I'm not convinced even ¼" material would resist bowing, especially if it was warmed slightly.

I used a piece of ¼" tempered glass for my window, a decision I never regretted.

Harold

 

[gold4mike]

I used 1/4" Lexan and it still bows a bit when I seal up too much of the opening. I'm using it to span a 30 inch opening.

I use a discarded furnace blower and wired up the high side. I will probably buy install a rectifier on it soon to gain some control over the draw.

 

[Noxx]

Thanks Harold.

I did not consider tempered glass because I thought that I could not find it locally. It is, however, not true.

I also want to share this company I found; http://www.onedayglass.com

They can cut tempered glass to specific sizes and drill holes for very cheap. They also ship in CONUS.

 

[Claudie]

I get my tempered glass from discarded entertainment center doors & shelves. The glass from cooking ovens is also tempered. Many storm doors have tempered glass windows in them. Refrigerator shelves are also tempered glass. Tempered glass is everywhere.... :|

 

[Harold_V]

I get my tempered glass from discarded entertainment center doors & shelves. The glass from cooking ovens is also tempered. Many storm doors have tempered glass windows in them. Refrigerator shelves are also tempered glass. Tempered glass is everywhere.... :|

Shower doors are tempered glass, too. (That's assuming they're not plastic)

Harold

 

[Harold_V]

Thanks Harold.

I did not consider tempered glass because I thought that I could not find it locally. It is, however, not true.

The one real negative is that ¼" (6 mm) glass weighs about 3½ pounds/square foot. It can be a handful to handle. Mine was much smaller, so it wasn't an issue.

Harold

 

[4metals]

If you know any woodworkers you can use a rail and style panel door frame to frame some cheap plexiglass.

If you know someone with the router bits to cut the pieces it can be very economical.