My buddy just called me back and can make me a 450 gallon aluminum storage tank for about $1200, including all fittings. I'd like to go bigger, but just don't have the room in the basment for anything bigger than that.
Pat
Pat
henfruit said:hey pat, will your tank be pressurized? round or ??? size.
henfruit said:sounds like my plan . but iwant more gallons.
Fred61 said:If there is going to be any copper in your system you had better not use any aluminum in any part of it. Same with galvanized fittings. It will all corrode due to the dissimilar metals. I'm sure people that know more about it tnan I will chime in when they log in and see your headline.
Tennman said:What kind of pressure are you talking? Just a 2' diameter surface in the middle of one side will have over a 2,000# load at only 5 psi. Flat sided pressure vessels try to make themselves round. Pressure vessels are typically round so the vessel's wall is only in tension. If there is much of any pressure, a flat sided pressure vessel will require someone to do some simple beam analysis on the stiffeners. Not trying to rain on a parade but you could end up wasting a bunch of money or getting hurt.
hayrack said:Don't use any galvanized fittings. Galvanized will destroy your circ pumps. You should be able to find a used propane tank for little or nothing.
henfruit said:Hey pat i think we need to do some re thinking? or use them not pressurized.
Galvanic corrosion continually affects all underwater aluminum, but at a reduced rate when no dissimilar metals are connected to your aluminum parts. When in contact with an electrolyte, most metals form small anodes and cathodes on their surfaces due to such things as alloy segregation, impurities, or cold working.
We have used stainless steel (cathode) and aluminum (anode) in this discussion as an example, however other metals coupled with aluminum also produce galvanic corrosion cells. For example, zinc connected to aluminum will form a corrosion cell, but in this case, the aluminum becomes the cathode and the zinc (anode) corrodes. One of the worst couples with an aluminum drive would be connecting it with copper or a copper alloy (bronze).
dirttracker said:FWIW, we had a vacuum chamber built at work to perform electrical tests at a simulated altitude. The chamber was intende to be good to at least 70,000 ft altitude equivalent pressure. It's a cube about 40 inches on a side, the walls are 1 inch thick 6061-T651 aluminum plate. For electrical and fluid pass through connection areas we used 1.25 inch thick Lexan. I've seen this chamber go to ~1 psia, an equivalent pressure differential of ~13.5 psi inside to outside. Based on this construction, I think you will need thicker walls for your pressure tank. Even if it's made of steel, 3/16 starts looking pretty thin when you consider the forces.
As everyone else has said, aluminum and copper don't mix with a water heating system. I've been involved in designing aluminum heat exchangers to run with liquid cooling systems. Even with corrosion inhibitor, using aluminum and copper with any water based working fluid (usually propylene or ethylene glycol based) is a bad idea. This goes double at high temperatures, like where you would run a heating system. The last propylene glycol/water system we set up, we had to go through every piece of equipment that would ever come in contact with one of the heat exchangers and make sure there was no copper anywhere in the system. Even to the point of using nickel brazed flat plate heat exchangers in our test equipment instead of copper brazed flat plates. If there was any copper present, the filters would plug with blueish-grey paste.
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