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What is the maximum PSI a polyethylene 'tote' water tank can hold? ?

I am building an irrigation system, and I have an Plastic 100 gallon translucent poly tank that is square with skds on the bottom and top.  It was previously used for holding and transferring used vegetable oil.  For my irrigation system to work properly I need to find out if it will safely hold 70 PSI of air pressure.  It looks like it would, I THINK it would.  There is a molding seem in the middle all the way around which I thought I could wrap a tow strap around for added strength.  I know they are not designed as pressure tanks, but surely someone out there knows what the breaking point of one would be?

this link shows what it looks like;  http://www.gototanks.com/300-Gallon-All-Poly-Tote.aspx

Thank you very much for any help I can find.

Larry

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biggestdog420 (author) 4 years ago
here are pics of the pump I have.. I have also found a 100 gallon used air compresser tank. (you guys convinced me that using the plastic holding tank is NOT a good idea even at 70 PSI max). Now I need to figure out how to drill holes and thread inlet and outlet in the aircompressor tank, as well as two smaller holes for the pressure guage, and the 40/60 pump switch. AND probably one for a safety pressure valve.

The pump is a Red Lion RLSP series, 1.5 HP, 71 GPM, 44 PSI Max.  2" suction and 1 1/2 inch discharge pump.

PUMP PICS 479.jpgPUMP PICS 480.jpgPUMP PICS 481.jpg
Please save yourself the work,  there are plenty of tank fittings
that have the connections you need  :-)    .   .   .   A
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With such a large surface area, the total force that the walls have to resist will build up quickly. At 70 PSI, there would be 10000Lbs of force acting on each square foot, which will likely tear the tank apart. I would imagine that a tank like that would deform a fair bit with under 10PSI.

Unless the tank you have has some substantial reinforcements, trying to pressurise it will not end well, though if you have a compressor, you could try putting a low pressure in while the tank is full if water. (the water greatly reduces the size of any explosions that may occur.)

Perhaps a scrap compressor tank would be a much safer and fairly cheap solution.
biggestdog420 (author)  The Skinnerz4 years ago
thats dissapointing, but it seems like accurate information. I really do need a metal tank. I might try to pressurize it slowly to just see what happens. I also imagine that cycles of pressure and depressurization would not help at all.
If you do try to pressurise the tank, fill it with water first. This will make pressurisation faster and will reduce the damage done if anything fails.

What are you planning to do with the water as it comes out of the tank (is the pressure needed to push the water uphill?)

As the other posts suggest, a pump is probably a good solution. If you really need it to be air operated, there are air operated pumps which you may be able to aquire used for a reasonable price.
biggestdog420 (author)  The Skinnerz4 years ago
my plan is to have it 60% full of water, 40% full of air. I have a pump that goes into the tank and when the air pressure reaches 60 PSI, a switch cuts the pump off and the pipes are pressurized. This enables me to slowly draw down the tank by using sprinklers on the gardens. When the air pressure drops to 30 PSI the pump turns on and repressurizes the tank. This scheme provides a cushion to avoid water hammer/ and the pump cutting on and off constantly and abrubtly.

the lift to the gardens is approximately 12 feet higher and about 300 feet away from the water source.
The Recreation Vehicle ( RV ) of which I speak has a polyethylene water tank the size of a 3 person couch considerably thicker then the image you point to and is not pressurized.
Instead as Steve and I both suggest use a DEMAND WATER PUMP.

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biggestdog420 (author)  iceng4 years ago
a demand water pump would not work in this application. I want to irrigate 5 different zones all with differing pressure needs. I also need to charge anywhere from 2 to five sprinkler heads simultaneously.
Demand pumps can easily handle that, an RV pump would be too small for you.
Pressurising a tank like this is tantamount to building a bomb. It isn't designed to handle it, and 70 PSI will cause a pretty devastating bang when it blows.

You should use a pump.
iceng4 years ago
if you are into irrigation, why not consider an after pump, like the type used in an RV water pump that runs all the time pressuring up the faucet to 50PSI and stops until a faucet is turned on and water flows :-)

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