Assistance in choosing a large air source

[cammyd32]

In the world of spudding I am mainly an ideas man, I spend hours perfecting designs and CAD'ing them etc, very rarely do I actually make any of my designs. but I would like to start testing out some of my long winded ideas, but for this I need an air source that contains, or can maintain a constant flow of gas.
The obvious solution would be a compressor, but I can't really get hold of one as I need the money for the lathe I am going to buy in a few months time, so
I thought if I could get hold of a large ex propane tank and unscrew the top and feed a schrader through the side of the tank, I could then rig the top valve onto a simple quick connect fitting onto which I could then attach any newly to be tested idea I want.

But there are problems....
firstly I am very unfamiliar with the entire layout and valve types of a propane tank, I have never possessed a barbecue, and as a child my parents hated the notion of camping, so I have never had one laying around I could look at.

I wish to know;
If the top of a tank (generally) can unscrew and if it would be possible (via a Schrader loosely taped on a stick etc) to feed a Schrader into that hole and maneuver it through a hole in the side (will then be compression fitted)

How much pressure one of these beasties can take? (roughly, I know it will vary from model to model)

What valve attachments are on the tops of these tanks? Is there anything that I will need to buy to be able to attach a pressure rated hose to it?

Is there any more practical solutions to this problem?

Any further questions or answers are as always welcome.

[jrrdw]

Well, how do you intend on filling the modded propane tank? If you can fill the propane tank can't you save the money and trouble and just fill the cannon with the same source?

Unless it's just the thrill of building (customizing a tank) I see that as a unnecessary part, unless you need it for portability...

You can make your own hand pump but filling a large chamber is a lot of work. When it comes to air compressor's you get what you pay for.

[Gun Freak]

If you're going the propane tank route, I think it would be easier to just use propane. Just remember, propane refills cost money, as do all of the accessories you will need to buy to use it for this hobby, so in the long run, buying a little $100 compressor will pay for itself. You won't have to worry about conserving it, you can just go crazy

[cammyd32]

Well, how do you intend on filling the modded propane tank?

I am going to fill it via a petty car tyre compressor that I do have, it can be kept attached, to the tank and keep it topped up in breaks in firing or testing but it is soo awful it can't maintain a stream of air at 10psi let alone 150.

propane refills cost money

exactly why I am not going to use propane, just keeping the tank filled with air is a)free and b)less complicated

As for buying a compressor, its just too expensive. I have a fund (kind of like a swear jar) that I put money in especially for this hobby, occasional fiver's loose change etc, but with the rise of more digital credit cards in my life I have little change that is entering my fund. lol so consequently my budget is small

[Gun Freak]

That little compressor will probably burn out if you use it to fill a big propane tank. Not to mention how ridiculously long it would take to fill. Can't you find a used compressor for cheap?

[cammyd32]

That little compressor will probably burn out if you use it to fill a big propane tank. Not to mention how ridiculously long it would take to fill

That is a point but surely when the thing is filled with about 150 psi it would be OK for maintaining that pressure, as long as the air is used in bursts.

But I really can't find a compressor that is in my price range that would be decent enough to provide a constant 150 stream though

[warhead052]

I would suggest an HPA tank with a regulator. Its then compact, and supplies 150 constantly until it runs out.

[cammyd32]

I would suggest an HPA tank with a regulator. Its then compact, and supplies 150 constantly until it runs out.

It would be good but unfortunately due to a load of recent shut-downs the nearest place I can fill a tank would be 10 mins away, in no direction that I go regularly, that and it would cost (not much, but the principal is the same) to fill up the tank.
also the time it would take to use up a tank would not be that long, when paintballing I used an entire tank in one game (about 150-200 shots) bearing in mind the trip cost (fuel) and the tank refill cost, it is certainly not a cost effective or practical solution I am afraid
y'all see the dilemma I am faced with now?

[warhead052]

What about building a HPA pump as well as the HPA tank? That way all you have to do is spend a few minutes of your time pumping it up, and you are set for the next round.

[cammyd32]

What about building a HPA pump as well as the HPA tank? That way all you have to do is spend a few minutes of your time pumping it up, and you are set for the next round.

That is a good idea, but what if the two ideas are combined so I have a Propane tank piped up to a HPA pump = problem solved.
I may need one of those new fangled two stage pumps though

[Gun Freak]

Hpa tank + regulator + hpa pump = a hell of a lot more than a compressor.

Plus refills take a really long time. I think LnL takes like 30 minutes to refill his.

Any pump will have a hard time and take a lot of time to pump up a propane tank. I still suggest finding a compressor.

[cammyd32]

Hpa tank + regulator + hpa pump = a hell of a lot more than a compressor.

Good point, paying out for all those will certainly defeat the point of 'going on the cheap' and with no clear advantages over an equally costing compressor, it doesn't really seem worth it.
hmmmm .....

[warhead052]

3500 psi not worth it? I would say it is, depending on the project.

[cammyd32]

yea 3500 psi is good, but as you said maybe not for my line of 'airsoft' style projects, that and as stated earlier for the price it shows no real advantages over a compressor.

[warhead052]

Well, if it is regulated down enough, or in a small enough chamber, then it may be ok for airsoft. Maybe in the case of a sniper to get the distance factor.