This is Gary Reif's post on the Yahoo
Simply Solar group describing the solar heated water storage tank that he built
using a paint in, flexible, polyurethane tank lining product call
The PermaFlex is said to remain flexible for "life" and to be good up to 250F.
This looks like a promising way to line tanks, but bear in mind that (as far as I know) it has not been used extensively solar heat storage tanks. Also, bear in mind that Gary took great care when building the tank to avoid gaps and to build stiff walls that will deflect very little -- this may be an important factor in having success with this paint in liner.
Thanks very much to Gary for providing this material!!
3/4" sturdi floor which is an extra strong
tongue and groove plywood for floor construction and laminated it with 1/2"
plywood to get 1 1/4 thick sheets which make up the tank. 4 vertical inside corners are just 2x4's butted in corners for strength. Floor is the 3/4 sturdi floor on a 2 x 4 frame wide side laying down with about 16" spacing squared since it's a lot of weight. I used lots and lots of 2x4 around outside of tank since this 900-gallon tank is holding back 7500 lbs of water.
Four coats of permaflex on the inside of the plywood, which is easy to do but
stinks and strong fumes since you are in the paint painting it on. It's a rubber
PermaFlex lined tank with heat exchanger.
Routing pipes over the top of the tank sides avoids penetrations.
Info from their website http://www.sanitred.com/permaqualities.htm
SANI-TRED PermaFlex is a single component (1 part), liquid rubber "ULTRA ADHESIVE" paint-like coating. After cure, there is little resemblance to paint. PermaFlex is a paint replacement product, self-priming, easy to use, easy to apply and cures reliably even in extremely cold temperatures. A good analogy of PermaFlex is "a roll on, seamless, flexible liner that bonds permanently to the surface and beneath the surface". PermaFlex bonds permanently to most all standard building materials.
I assumed it would fill gapes even
though the website says it doesn't and they offer a product that does, so after I
applied 1 coat I had to order the filler product which was a pain to work with.
To do it again I would on the bare wood use a product like PL400 to fill all
cracks/ seams/ screw heads and would put a nice radiused bead in corners then
coarse sand it all to get adhesion to PL400. Doing this would make applying the
permaflex much easier and would have a better tank with less chances of a leak.
Hope this helps.
Gary will answer email questions at: greif123456789 AT yahoo DOT com (replace AT with @ and DOT with a period)
Gary November 21, 2010