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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.
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*****
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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