7 replies to this topic

[Carbon]

It was my daughter's birthday today, and we got one of those helium balloon kits (like these). After I finished filling the balloons, I got to looking at the tank. It's metal, lightweight, reasonably small, and uses threaded fittings which you could replace with something of your own design. I did a bit of reading online, and it says that these things ship at 260 psi, and are pressure tested up to 350. To give you an idea to as the size:



This thing is light, and has a listed capacity of 8.9 cubic feet. I could see this as being a nice portable airtank for refilling in the field.

So now, the question is, has anyone ever tried refilling one of these things? The tank has warnings of loss of life and limb, but I would think that sensible pressures would be quite doable for a welded steel tank. It has nice potential, but I don't want to die trying. (Exploding steel tank = bad thing. Plus, I think the landlord might object.) What are your thoughts?

[ompa]

I'd shy away from something like that, for this reasoning: Say you're filling up something, but don't have it properly screwed on, and it's attached to a hose. Now, with a balloon, if it flies off it won't hurt you. But if it's a piece of pvc or brass, and it comes off, that thing will cause some serious damage. I'm sure you could USE it, but I'd be scared that whatever I would be filling would blow up/come apart.

So basically, I wouldn't be worried about the tank, but what you plan to use WITH the tank.

~ompa

[nerfer34]

I'm kinda confused. You want to use helium to propel darts? And you want to refill the tank with helium? Naw I have refilled things like that(large co2 tank) and it said DO NOT REFILL but my dad and I did and it was fine. YOu just have to know what your doing and make sure thaere arne't any hazzardous things around. Also how expensive was the tank.

EDIT- agreed with OMpa.

Edited by nerfer34, 21 May 2006 - 09:10 PM.

[Carbon]

I see what you mean, ompa. Yeah, any sort of filling system would have to make sure that if it pops out, it won't lose all of the pressure uncontrollably. I actually hadn't thought that far forward, mainly because if this thing is a time bomb, I'll never get to part B. I was thinking casually along the lines of a regular air fill stem, or quick-connect fittings, though.

Sorry, I didn't say what I was going to refill it with....I was going to just refill it with air. The tank was $25. I was figuring someone had experience with refilling "non-refillable" containers, thanks nerfer.

[Pineapple]

There were, back in the day, conversion kits were available to allow compressed air to be stored in used 5 gallon R-12 "Freon" tanks. They were handy for filling up tires at the drag strip, or pumping up air shocks. Basically a low-cost air storage device.

While the helium tank in question is rated at 260 shipped, and 350 maximum pressure, most household air compressors max out at 130-150 psi. My "big" Coleman 6 horsepower air compressor and 27 gallon tank (used with my nail guns and pneumatic tools) tops out at an "industry leading" 155 psi, with a safety factor of 275 psi.

I doubt anything you have on hand would be able to blow it up outright. Maybe, MAYBE the service station air compressor might (I remember back in the 80s, the air compressor was a Saylor-Beall 50 horse motor pumpin' a whopping 150 gallon storage tank...don't remember the max pressure), but it's not the tank I'd worry about. It's the helium fill-up fittings. Try checking around (mainly auto parts stores) for conversion kits. That would be the wise thing to do.

If I did have a tank like that on hand, and I had the choice, I'd fill it up, probably keeping it under 100 psi. Heck, the helium tank is a whole lot stronger than 3 inch SCH40 PVC (what I used for my airtank on my spud cannon).



-Piney-

[Flaming Hilt]

Nothing could really [i]blow it up,[i] but if you want an idea as to how much 300 psi is, fill up something with 300 quarts of water and throw it at something... if you can. Anyways, yea, I'm not sure I have anything which will hold 300 quarts of water, much less nothing that could withstand having that container thrown at it.

Quarts? Pints... something like that. 300 of any unit is still a lot.

[nerfer34]

My Sports Authority fills anything basically. I have filled up co2, helium tank, propane. I do believe they have pressurized air which would work awesome. But again those safety hazzards. But it would be cool in the middle of a war with a light tank on you back and an RF20 modded so you have basically unlimited air. Then you turn the knob to release the gas and then you see everyone just falling to the ground.....

[Doom]

You shouldn't run into any trouble given that you don't overpressurize the tank and you use the correct threaded fittings and such. Avoid schrader valves and go for a simple air coupler and a real check valve and a pressure gauge. Check out Home Depot or Lowes for the correct fittings and such. The air couplers are much better than schrader valves because they give you a perfect seal and they're designed to take actual pressure.

Recently I have been doing something similar to an old air tank we've had for several years. At 125 PSI, it contains about 7 gallons of air, which is enough for several 8 liter shots at a regulated lower pressure in a water gun (not for a Nerf gun sadly). The valves were threaded on, and luckily the tank used a simple 1/2" threaded fitting which allows me to use PVC or a more expensive steel pipe. I also looked at my options for an upgrade, and I've seen $35 air tanks that hold 11 gallons of air, which might be a good option for this water gun in the future.

I also have been fixing up an old propane tank we've had for even longer, but I'm afraid that it is too heavy for use as anything other than a backup supply of air.