MOTHER'S HYDROSTATIC PRESSURE TANK TESTER

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Well, relax. Here's an extremely simple hydrostatic pressure test stand that you can whip together in just a few minutes from odds and ends that you may already have lying around the shop.

The design philosophy of this little gem Is just about as basic as basic can be:[1] Dig a small "doesn't have to be too good as long as it'll work" hydraulic cylinder out of the back corner of the shop. [2] Fit the cylinder's ram with a handle mounted to a scrapped-together base (so when you work the handle, the cylinder will act as a powerful hydraulic pump). [3] Plumb the pump you've just built between two check valves as shown here, hook the "in" end of the assembly to a source of water, and-using pressure clamps-fasten the "out" end to a fitting on the tank you want to test. [4] Use any method you find convenient to plumb a hydraulic pressure gauge to another fitting on the tank ... and [5] pump away.

You'll be amazed at how easily you'll be able to pack pressure into the container with your little test stand ... especially if the cylinder you've modified has a bore of one inch or less. (in MOTHER's research shop—where the rig shown here was built-we just happened to have a two-inch-bore cylinder lying around, so we used it. And the setup, as you can see, works. It does take some muscle, though, to pump that handle once you've built up a pressure of 200 or so pounds.)

A good rule of thumb is to test any tank you intend to put to critical use-say, as an air bomb-to twice its standard working pressure. And a second good rule to follow is to limit one of the water heater tanks shown here to a working pressure of 125 pounds per square inch (psi). Which, of course, means that you'll be testing your tanks up to a pressure of 250 psi or slightly higher.

If the tank you're testing will take the pressure, you'll soon be absolutely certain of that fact. And if It won't? No problem. Unlike the dangerous "explosion" that results when a container of air under several hundred pounds of pressure ruptures, your water-filled tank will merely spring a leak (see photo) or-at worst split a few inches along its weak seam.

One final note: After you've certified a tank for 250 psi and you know It's positively safe to use the container as a 125 psi air bomb ... make sure that you limit the drum's standard working pressure to that level. How? By Installing a 125 psi pop-off valve on the tank, that's how. And by checking the valve from time to time to make sure it's functioning properly.

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