Converting Scuba Tanks into Constant Pressure Source

You have to figure cuft per minute...This would only work for a few minutes...Scuba tanks only hold 80 to 100 cuft....How long does the tank last with you breathing it should give you a clue....

You might be able to get it down to 6cfm....

http://www.spraygunworld.com/Information2/CFM.htm

I'm curious about the project.

Seems like you could use a generator and just plug in a conventional air compressor or airless spray machine.

30 bucks can get you a small AC/DC compressor.

http://www.ebay.com/itm/Portable-MINI-AIRBRUSH-AIR-COMPRESSOR-KIT-SET-Hose-Makeup-Cake-Tattoo-Nail-Hobby-/190766771776#ht_4428wt_1399

I have no experience with anything, but that has never kept me from expressing my opinion before.

Armed with the minuscule information you provide, the "painting project" seems secondary to defying the laws of physics.

What is the project? How many square feet? What kind of paint? What viscosity is the paint? Inside, or outside? Commercial, residential, hobby, artsy?

Why use small tanks with very limited capacity that are expensive to refill (scuba compressors cost 5-10,000.00 USD to buy) and potentially lethal if misused, when a couple of spare tires might be all you need?

Airbrushes used to come with a spare tire Schrader valve fitting as art of the kit.

Well if you're going to go down this path why not use CO²...?

http://www.casesforvisualarts.com/makeup-airbrush

http://www.tippmannpros.com/c-138-co2-tanks.aspx

I've got spare tires. Well, actually I've got two CO² tanks too.

And a paint ball gun, for sale, cheap.

OP, interested?

I can post pictures.

These come pre-charged, and in lots of different colors.

You come to my town with that box, I'll have you arrested.

I didn't think kids were allowed to buy them anymore.

Buy, who buys? They steal, they don't buy.

PD caught two taggers with backpacks full of spray cans the other day.

That was after they were watched for two hours on cameras tagging, resting, smoking, and tagging some more.

This message brought to you as a public service.....

http://www.howcast.com/videos/327974-How-to-Tag-like-a-Real-Graffiti-Artist

I'll be sure and send this to the gang squad at PD. They'll get a kick out of it.

CO² ≠ CO₂

SCUBA setups do the same thing as you want, just at slightly different pressures. You might be able to combine a first-stage SCUBA regulator with a second-stage welding regulator; an oxygen regulator has a good output range.

Welding regulator. Looking in to that now. Thanks! I just need a secondary reg that uses a bladder so there would be no air loss.

GreenTeaGuy-

If you use an Oxygen Regulator, don't ever use it for oxygen again! Any oil contaminants, no matter how small, could cause an explosive situation.

Good Luck, Old Salt

Good comment!

GreenTeaGuy-

Go down to the local Fire Dept. that has a rescue truck and ask them to see there portable compressed air source. That is what you are describing.

It consists of either a 2,200psi or 4,200psi cylinder, the same as used on Self Contained Breathing Apparatus (SCBA) and similar to a scuba tank, a double stage regulator, a relief valve, a hose and a quick connect. This is often used for air chisels for cutting cars, air powered saws, impact hammers, etc. If you are going to fill it at the same time you are using it, forget about it. The compressors for them cost over $20,000 and are not portable. Also you need a containment unit for the cylinder that is being filled.

For painting purposes a small compressor, either electric or gas, will cost a fraction of the above described system. For $300-$500, less than the regulators, you can have a nice portable unit.

Good Luck, Old Salt

Er, instead of all that work, wouldn't it be easier to hire an air compressor for the duration of the painting project, set it to <...15-25psi output...>, and return it to the hire shop once the job is done?

I've been using these for years, with great results. All that's needed is a non-pressurised, small container, that's open on one end.

The use of dive bottles is very common around here for running air tools underwater. I have also seen them used for sprayers- for example in bleaching a boat bottom "on the tide", and as "air pigs" for roadside vehicle air by truck fleet operators. If you live and work in an environment where these bottles and the filling stations are a common resource, then you are bound to run into a local diver who has done this.

If you need constant pressure output, your regulator is the key element to address.

"Oh , if only he were still alive"....

Well ... waste-not an opportunity to praise a mentor... About 23 years ago, the fellow who certified me (PADI/scuba) volunteered to help me paint my 1981 Dodge pickup:

"Diving Don" Serbousek (quite the "legend" even in his own days, having held Admiralty Claim on the SS Commodore, among other titles*) assured me he would do a "bang-up-job" (best-for-my-buck), and that scuba air was IDEAL to use due to the super-low (6%) humidity.

As I recall, we used 3-fills (of twin-tanks, thus 6 bottles) for the primer, and likewise for the silver finish.

To this day, I still have (and use regularly) the regulator that he modified for me to keep in my car for filling tires etc. (bottle//1st stage regulator), having a "screw-adjustment" for delivery pressure.

Just HOW badly do you want to use scuba-air, as opposed to an easier compressor?

* (( he made an appearance on "I've Got A Secret", due to having the skeleton of the largest mastadon found in North America in his attic! {here, too, under "Tusks! Ice Age Florida's Mammoth and Mastodons"}))

[ from above: "the regulator that he modified for me to keep in my car for filling tires etc." ] ... I took a few pics before heading to work this morning:

Note that this is *not* the one used on the twin-bottle setup used for the painting of the truck. Other than replacing the gauges over the years due to glass breakage, haven't had to do a thing to it. Will make a dandy air-brush-supply for somebody one day...