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Aquarium specs are for open-top boxes. If your tank has a permant
top, if even partial, or a lid with a lip all the way around that
holds the top square, you'd prevent bow where it matters most.
You could also consider building a handsome wooden or metal "frame"
that acts as an exoskeleton. This is, in the very least, a viable
contingency should you find dissatisfaction with your 3/8" tank.
Jason
On Nov 8, 2006, at 4:43 PM, Stuart Kohlhagen wrote:
> ISEN-ASTC-L is a service of the Association of Science-Technology
> Centers
> Incorporated, a worldwide network of science museums and related
> institutions.
> **********************************************************************
> *******
>
> Jeff,
>
> The height of the fluid in the column or tank is one of the main
> factors
> that influences the "correct" thickness, as that obviously drives the
> pressure. The other factor is the width of the tank. The wider the
> tank,
> the more flex or bowing that a particular pressure will create, AND
> the
> stiffness of the material is important too. The thicker the
> stiffer, but
> also remember that glass is much stiffer than plexi. Applying glass
> based aquarium rules of thumb to a tank built from plexi will give
> you a
> tank that bows a lot more ( often about 10 times that of similar
> thickness glass). And while the plexi can withstand the pressure, the
> flexing tends to focus stress in the joints which tends to let go,
> or if
> your gluing is first rate, the glue holds, and the plexi fractures
> next
> to the glue. If the amount of bowing is not a problem, make the sides
> of your tank from inch square stock ( plexi, aluminium extrusion, etc)
> so the edges have a wide contact area to support the bonding, and
> spread
> the stress from the flexing. Also makes it easier to run plumbing into
> and out of the tank if your creating a flow tank.
>
> Not a definitive answer, but hopefully some help.
>
> Cheers
> Stuart Kohlhagen
> Manager Exhibition Services
> Questacon
>
> -----Original Message-----
> From: Informal Science Education Network
> [mailto:[log in to unmask]] On Behalf Of jeff courtman
> Sent: Thursday, 9 November 2006 8:25 AM
> To: [log in to unmask]
> Subject: exhibit geek question - plex and tall water column (but thin)
>
> ISEN-ASTC-L is a service of the Association of Science-Technology
> Centers Incorporated, a worldwide network of science museums and
> related
> institutions.
> **********************************************************************
> **
> *****
>
> I'm building a thin tank to hold rheoscopic fluid. The tank will
> measure 72" wide x 40" high x 1" deep. While researching tips on
> aquarium building, I came across several sites that said any tank over
> 24" in height, use 1/2"+ plexiglas. Which got me worrying.....I
> built a
> prototype 24"w x 36" deep x 1" wide out of 1/4" plex with no problem.
>
> So I did the calculations and the static pressure at the bottom should
> only be about 1.6 psi. The weight of the water in the tank will be
> slightly more than 100 lbs; 12-1/2 gallons. So here's the question:
>
> Do you see any problems with using 3/8" plexiglas at this scale? (On
> the prototype, I made an epoxy fillet along the seams where the sides
> met the base.
>
> Thanks,
>
> Jeff Courtman
> Exhibits & Special Projects Coordinator
> 251.208.6851
> Exploreum Science Center
> www.exploreum.net <http://www.exploreum.net/>
>
>
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