Some Help w/ a Different Kind of OBA
 

I have several great condition SCBA cylinders made by Scott that I would like to use as a source of on board air.

The cylinders are aluminum, about the size of a rolled-up foam sleeping pad and weigh about 20 pounds. Each is capable of being preassurized to 4500 PSI safely.

As of now, all they have is a male threaded output and a on/off valve.

For those of you that have made homebrew CO2 setups and such, where did you get your componets, how much were thay and how well do they work.

The threading on these tanks may be the same as a CO2 bottle, but if not I will have to make my own system. I assume I need a regulator, a connector and a fill hose. I should be able to easily inflate my 4 tires very fast with one of these, and I have acess to a compressor that can fill up to 7500 PSI.

Please help me find/assemble what I need to make these work.

BTW- Please don't clutter up the thread with safety warnings. I wear them on my back on a day to day basis doing things much more risky than wheeling and I have a brain in my head so I can secure and protect them.

Thanks!
Lamm

I have a homebrew set up. I like it and it works flawlessly.

I purchased a CO2 regulator for restaurant use off of EBAY. Cost was around 30 bucks w/shipping, brand new.

The regulator goes up to 130 PSI, and has a screw, so its adjustable. I have it set at 110, so my tires fill in around 40 seconds from 15-31. It can be adjusted for use with air tools.

I purchased a coil hose from the hardware store, 10 bucks, and fitted it on either end with a female quick connect, and put a male quick connect on the regulator, and on my guage set up.

The hose works well, although it does freeze at the regulator end towards the end of the fill. I will be looking for something different soon, but i'm not too worried about breakage, it hasn't had a problem yet. It is, however, a posiblity.

I then made a neat little gadget from parts at the hardware store, and THIS air guage. What i did was break the schrader valve on the end of the guage, so air can pass freely through it, without any resistance, or the schrader needing to be ingaged. I added some adapters to get it to 1/4" NPT threads. Then, i added a short air hose, to get enough distance that i could stand upright while holding the valve that i attacted to the end of the short hose. It is a 1/4 turn ball valve, with a small handle. Then i added a male quick connect to that.

So, all that, what good is it, you ask? Well, i close the valve, hook the end of the guage to the tire, and open up the tank. I open the valve, and let CO2 into the tire. When i shut the valve, the guage reads the pressure in the tire. Never have to disconnect to read the pressure. Its all quick and easy, and no trigger to hold down or anything.

Now, the only thing i would do differently than what i've got is to not use that guage, and instead build my own guage set up, so i didn't have to mess with the funky schrader valve thing.

Thanks Ike, good info.

There is a product made that does what I want exactly, but for the life of me I can't find it sold as a stand-alone unit, only in a $600-$1000 package. Hence the homebrew idea.

Lamm

You can find most of the stuff at a welding supply store.

I have PowerTank stuff, but if I had it to do again, I would go with OffRoadAir--
http://www.offroadtuff.com/HyperFloMAX.htm
The thing about having CO2 is that when someone sees you airing up, they will inevitably ask you to air them up as well--and even if they don't, I like being able to make the offer anyway. I have the 15# tanks but I wish I had the 20's just because they cost the same to fill--the place I get refills is $10 whether you have a 5, 10, 15 or 20# tank.
I think the regulators that OffRoadAir sells are better than PowerTank's regs and they are cheaper too.
A complete 20# system, tank, handle, fully adjustable regulator with liquid filled gauge, quality hose and chuck, plus the mounting braket-- for $350? That is a deal that can't be beat.
Now. Why not build your own? For one, you will have trouble finding anyone to dispense CO2 into your SCBA tanks. It may even be illegal for them to do so. All tanks have to be currently inspected and marked for use with CO2. Not that your tanks are unsafe--that is not my point. Even my brand new looking PowerTanks are given the once over for the current inspection date.
Secondly, you will want more volume of CO2 than your tanks will provide--once you have OBA--you go wild with uses for it and running to get it filled (a 30 mile round trip for me) too often is a bitch.
And lastly. The regulator will freeze solid and stop flowing unless it is designed not only for CO2 but also for the high flow rate. It is the flow rate that you are paying for. Beverage regulators that flow CO2 are rated in cubic feet per hour. A good OBA CO2 system will flow upwards of 20 cubic feet per MINUTE! You can see the problems that will cause if you fill up more than a couple of tires.
I think you were mainly talking about CO2 for OBA and not simply compressed air. Compressed air for feeding people is one thing but there just is not the capacity available in a bottle, at any pressure, to make it a viable option for an OBA system.
My current OBA system consists of one 24V compressor good for 16 CFM, a second 24V compressor good for 4 CFM continuous duty cycle, and two 15# tanks of CO2 for backup--all are capable of contributing to the system simultaniously, although I do not know why I would ever do that. I only have a single 5 gallon tank and that is the next upgrade I will make--adding a second 10 or even 15 gallon tank under the cargo area of my 4Runner between the fuel tank and the rear bumper.
Point being I have been tweaking this system for about 2 years now and I have learned a little bit about what works and what doesn't.
I can tell you that if I didn't have a rig that sucked up so much air continuously (suspension cycling) I would never mess with a compressor and complicated wiring etc. I would just install a 20# CO2 system and be done with it. Hope this helps.

:alert: I am in the same line of work and considering the same type of OBA system. I got lucky and scored a high pressure regulator off a wrecked scott pack for mine, just haven't got around to putting it together yet. The nicest thing about Scott is that all their packs (except the GX2) have the same thread setup, so if you can find an old Scott 2-A pack(usually VERY cheap since nobody wants them any more) the parts will work perfect for you. The only thing is that you need to make sure that the bottle doesn't overpressure the regulator, but I'm sure you got all that in rookie school. :chair:

Hope this helps.

:good:
Most EXCELLENT post. :bigclap:

:guitar:

Just to clarify because I think some people may be mistaken, this will used compressed air, NOT CO2.

I have acess to a compressor that fills the bottles up to 7000PSI, the bottles are rated for 4500PSI so that is what I will fill them to to use, DUH!

I looked at a few regulators that might work at an Air-Gas shop but they were about $200, I would like something way cheaper than that!

Also, these bottles are often used to provide air to run an air hammer, impact wrench or even high preassure lifting bags that can lift a railroad car, so I'm sure the power for some 32" tires is there.

Lamm

i dunno about 4500 psi on a trail, depends on where u go with it i guess

Well, I'm ok with climbing 105' ladders, standing on the roof or burning buildings and crawling around burning buildings with it strapped to my back, so I think it will be just fine in a nice wooden, latching box I plan to make for it. :)

I'm no dummy, I can keep it secure.

Lamm

Come on Lamm, lighten up man. :D No one has called you a dummy.

You posted up to get some feedback and you've gotten some good comments.

IMO, cheap and high pressure - pressure vessel don't go together - as I like you have my vocational area of expertise - I'm a pressure vessel fabrication engineer. :hillbill:

I'd spend the money to get a quality regulator or just spend the same money to get a quality, proven system.

Good luck.

:guitar:

I'm not angry or offended, I just think I am not making myself clear enough.

As far as the tanks, they are not really cheap. They cost hundreds of dollars new and mune are in great shape with current hydrostatic certifacation. I was justa lucky SOB and happened to get them for free (not a 5 finger discount).

Do you think if I bought a $200 some regulator it would be all A OK. To me it seems that if the regulator fails, big whoop, but it is not a safety issue as the tank is still intact and can be shutoff on its own(Maybe I'm worong?).

Hence the want for a cheaper regulator. I'm not going to be using this more than 2 or 3 times a month either.

4Mogger had some great info, but I think he thought I wanted to use a compressed air tank for CO2, I do not.

Thanks!
Lamm

Im no expert here by any means, but sounds like your on the right trail here lamm!

Lamm,
I am no longer discussing safety since I think you understand better than the average person the slightly evelated risk of carrying around compressed air.
You are talking about spending some pretty serious cash on a regulator to make your bottle(s) safe and functional.
Before you do that. I would recommend finding someone who has done it and deflate your 32"? in tire to 5 psi and then try to fill it up with the compressed air. I am guessing that a single bottle will not even get you back to road pressure on one tire--let alone four-- and God forbid you have to reseat a bead and run out after a few blasts and are stranded.
The point I was trying to make. A beverage CO2 bottle is damned cheap (usually free) and many places just do a direct exchange instead of a refill--all you need to add is a hi flow CO2 regulator (cost as little as $35 for a quality unit) and some kind of handle if you want.
So for somewhere in the neighborhood of 50 or $75 bucks you have viable OBA that I would estimate would give you, at a minimum, 100 times the volume of air vs. the compressed air bottle.
That it doubles as a fire extinguisher and is safer than compressed air are just bonuses.
If I am coming across as being a little over the top with the pushing of CO2 it is only because out of everything I have added to my rig, it is the CO2 bottles and their many uses that I have been the most impressed with.

Ahhhhhh, OK.

Perhaps a test is in order then.

Lamm