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how far will a nitrogen tank get me?

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Member Posts: 57
OK while airing up a radiant or snow-melt system dragging around my old Emglo compressor is a pain in the .... uhhh  back! I know Nitrogen systems can carry more pressure. Has anyone used this for filling a system and figured the cost difference?

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• Member Posts: 10
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nitrogen volume

It depends on what you are pressure checking. A typical 3000 psi nitrogen tank will have about 300cf of nitrogen. So the math to figure this out goes something like this:

internal volume of plumbing being tested (converted to cf) * test pressure (converted to atmospheres) = cu ft of nitrogen used.

E.G. 3.5 cu ft of internal volume * test pressure 6.8 atmospheres (100psi) = 23 cu ft of nitrogen used.
• Member Posts: 2,666
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I do not know what your compressor weighs.

When they replaced my roof, they had an air compressor big enough to run two compressed ai nailer guns at once. I could not have lifted it, but one of those guys did. Where I used to work, we used to get those nitrogen cylinders that are about 5 feet high and a little less than a foot in diameter. It takes two guys to horse one of those into a truck where they must be chained to something secure. Where we were, it was not legal to let them roll around in the bed of a pickup truck. I heard about one that was improperly fastened and it fell over in an unfortunate way, so the regulators broke off. The thing shot around like a rocket. I am glad I did not get to see that.

Are you sure that is a better way than an air compressor. I know you can get much smaller tanks, the size of a small fire extinguisher. But they would probably use up pretty quickly.
• Member Posts: 105
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farther than you want....

When I worked at Digital in Hudson, MA clean room, a co-worker knocked over a 5' tank of HCl so the valve hit a step - it snapped right off the top of the tank, and the tank went right through the concrete block wall on the other side of the hall. When he got out of the hospital, they fired him for moving it without the cap in place. Now, nitrogen isn't nearly as nasty as Hydrogen Cloride, but still.....

http://www.airgas.com/content/details.aspx?id=7000000000234

On the other hand, I have a ex-freon tank set up with regulator as an 'air-stealer', and a lashup of sharkbite caps and salvaged appliance gas connector bits on a tee with a shrader valve and pressure gauge - so I can goose up sections of piping to 60psi with air I bring from the shop or nearby handy compressor to see how I'm doing so far - always nice to test in sections so you can move on with confidence.

I suspect this is not legit either, at least not anymore - you used to be able to buy kits to reuse those tanks just this way...

still can - http://www.nationalwholesaletools.com/freontanktoairtankconversionkit.aspx

although that doesn't necessarily make it legit...

YMMV

Vbob
• Member Posts: 2,666
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a co-worker knocked over a 5' tank of HCl so the valve hit a step - it snapped right off the top of the tank, and the tank went right through the concrete block wall on the other side of the hall.

Yessir. And HCl is not what is commonly used in tear gas, but it sure makes the eyes water in very small doses, and induces coughing. But those tanks sure rocket around, as you described.

A friend needed to do some shock testing (physical shock, not electrical) where an extremely rapid impulse needed to be delivered with a lot of energy.  He took two large size nitrogen cylinders with just the valve (no regulators) , screwed on some quick acting solonoid valves, T'ed them together and off to a pneumatic cylinder. That really hammered the test object.

This is not the normal military shock test that involves dropping from a known height onto a steel plate, or allowing  a steel pendulum to fall from a certain angle to hit the test object. Those did not seem to be what he needed for his testing.
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