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From: Lew Hodgett (no email)
Date: Sun Oct 01 2006 - 15:56:48 EDT
Tom wrote:
> Mock up your tank using expanded polystyrene foam. The blue foam
rigid
> insulation by Dow found in home improvement stores like Lowes and Home
> Depot. I cut this with a "hot wire cutter" (Google is your friend
:) )
> but it is also easily cut with a serrated bread knife.
>
> Using layers of this foam tacked together with foam-safe adhesive.
Then
> by carefully carving the foam away, you can literally 'build' your
tank
> and make it fit EXACTLY into its allotted space. Carve and sand the
> foam into shape, rounding edges and corners. 'Organic' smooth shapes
> and curves tend to do away with stress risers. That is A Good Thing.
> 80 grit sandpaper on a small hand held sanding board cuts this stuff
> like butter.
>
> After creating the tank in foam, THEN glass it using epoxy resin
> especially formulated for tankage. Call the tech people at WEST, MAS,
> System Three, or whatever other company you source your epoxy with.
> Since I do not know the size of your completed tank, I cannot offer
any
> suggestions as to a layup schedule yet, but the tech support people
can.
>
> After epoxy glassing the tank, you can cut access holes and hatches.
> Cut circular, not rectangular, access entries. I would glass in rim
> support for the holes.
>
> Then IN A WELL VENTILATED place, pour a pint of acetone into the
hole.
> (You can even use gasoline, but you never heard it here.) The foam
will
> disappear into a sludge that can be poured out leaving you with your
> perfectly shaped tank shell.
Mikey likes it!!!!
SFWIW, "Tank Resin" is a VOC based epoxy primer which is also used as
"High Build Primer" for finishing hulls, it is not a laminating resin.
I built a 65 gal tank using 4 layers of 24 Oz, double glass.
You will find 17 Oz more readily available these days which is still
good. Use 5 layers if you want to feel warm and fuzzy.
Use sch 80 PVC couplings puttied to the glass on both sides for
process connections as follows:
3, 1-1/2 NPT and 2, 3/4 NPT.
The 1-1/2 NPT are for effluent, the 3/4 are for the vent and a future.
I laid up the tank, then cut off the top and installed a piece of 1/4"
thick polypropylene screen (has 3/8" holes on a diamond pattern) such
that the dip tubes are exposed to only effluent that has passed thru
the screen.
With the top off, the bottom of the couplings were puttied to the
inside of the glass.
After glassing the screen to the tank, the inside of the tank and the
underside of the top were coated with coal tar epoxy.
A 12x18 access hatch was cut out of the top, then this piece had 2"
glass laid around it to it would cover the hole.
Hatch cover was attached using #14x3/4', Pan Hd, 316L screws.
SikaFlex 291 and 8d finish nails as outlined by Norm, for the gasket.
Tank was placed between two bulkheads and against the starboard hull,
then foamed in place and taped over thus totally securing tank in
place and also eliminating any place for unwelcome critters to hide.
NO, I'm not concerned about having to remove that tank at any timr in
the future.
Install two (2) dip tubes. Dedicate one to a deck pump out, the other
to Tom's neat plumbing circuit for a Lavac.
It simplifies the plumbing and eliminates a 3-way valve.
> You can also make fuel tanks this way. But I digress.
My fuel, potable water and hydraulic tanks are also epoxy and knitted
glass, coated with tank resin before sealing.
Lew
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