SCBA Tank

[350xfire]

I have this "condemmed" SCBA tank. It is a Luxfer aluminum, I guess about 50cf. The tank was only 5 years old, but condemmed due to the fact that the valve was cross threaded and could not be removed (galled thresads). Therefore, could not be hydroed. After cutting the valve off and drilling it out, I have a decent looking tank with screwed up threads. The original threads are smaller than SCUBA tank threads. I was wondering if I can re-thread this to fit a SCUBA valve, have it hydroed and use it as a low pressure 50? Anyone out there done this. Luxfer, of course, says they will not do it since the tank was not originally built for SCUBA.
Thanks

SCBA = Self Contained Breathing Apparatus.... Not SCUBA, but a safety tank like those used by firemen...

 

[M_Bipartitus]

It's unlikely that a hydro facility would approve a tank that received such modifications after leaving the manufacturer. The heat from drilling and re-tapping the neck could cause unintended strains in the metal. I would not attempt it. You're better off taking the tank to a scrap metal dealer and getting a few bucks towards a tank designed for scuba valves.

 

[Scared Silly]

You can do what ever you want with the cylinder but no hydro shop will touch it as it has now been modified. I.e. material around neck has been removed to accommodate the different sized valve. DOT is very specific about removal of material around threads so much so that tools that re-thread scuba cylinders are not to be used.

 

[WD8CDH]

Makes a nice planter if you cut the neck off or you may be able to rethread the neck with a NPT tap and use it for air tools at under 300psi. Once the threads are damaged, it's absolutly no use as a high pressure tank at all.

 

[msmith304]

I have several old SCBA bottles lying around from work and have thought about it as well, but after contacting the manufacturer was also advised that they won't withstand pressure at depth like a SCUBA tank will. I wouldn't put it under high pressure air after its been modded either.

 

[WD8CDH]

I have several old SCBA bottles lying around from work and have thought about it as well, but after contacting the manufacturer was also advised that they won't withstand pressure at depth like a SCUBA tank will.

Sounds like they don't know what they are talking about. External pressure only DECREASES the stress on the tank.

The biggest problem with SCBA tanks (especially 2216psi ones), even if you can get a suitable valve, is their horrible buoyancy characteristics. They float way too much.

 

[txapacheguy]

Sounds like they don't know what they are talking about. External pressure only DECREASES the stress on the tank.

The biggest problem with SCBA tanks (especially 2216psi ones), even if you can get a suitable valve, is their horrible buoyancy characteristics. They float way too much.

I suppose it is better to revive an old thread than start a new one on this issue so here goes...

I came into possession of a Luxfer 45 cubic foot cylinder from an SCBA system for free. It looks just like this example, but cleaner. It has also has the backplate, harness, and a regulator. It is indeed rated for 2216 psi...
Mine Safety Appliances 5 447 1 MSA Airtank with Valve Asembly - RecycledGoods.com

The cylinder seems to have been built in 1998, and its last hydro appears to be September of 2001.

Is there ANY good reason I should attempt to keep and use this cylinder for diving?. I have been looking at either a pony or AL40 to use as a redundant air source, but my gut and the few things I have read tell me this bottle will not fit the bill.

It is light, so I agree that its buoyancy characteristics would likely be horrid and it would not be worth much for scrap aluminum. Since I have not pulled off the valve or found the info online, I do not know what the thread size is on the bottle for the purpose of valve replacement.

I am thinking that this rig might end up on ebay to offset the cost of my next dive gear acquisition. Please critique my thinking on this matter and shoot me a PM on the odd chance that any of you are interested in being the new owner of the tank, its back harness, and its regulator.

Thanks!!!

 

[elmer fudd]

If I were just a scuba diver, I'd be very hesitant about buying SCBA bottles. First off, they only have a 15 year lifespan. Second, there's the valves and third there's the buoyancy characteristics. Keep in mind though, that high pressure SCBA bottles are the absolute best thing out there for airgunners and paintballers. A 4500 psi, 88 cf bottle only weighs something like 25 lbs full and it gives them more good charges than considerably larger steel bottles. Brand new, with a din fitting they can cost over $600, (Airhog: Carbon Fiber Tanks). So if you find a good HP SCBA tank, chances are you can sell it and use the money to buy whatever scuba tank you want. Remember the 15 year lifespan though. A 14 year old carbon fiber SCBA tank is almost worthless.

 

[knotical]

Here's an interesting patent:
Air tank adapter for converting a self-contained breathing apparatus to a self-contained underwater breathing apparatus

 

[elmer fudd]

The guy I linked to in my last post can set you up with an adapter as well. He can probably get you DIN valves for SCBA tanks too. The tanks he sells come with them. I've dealt with him before and my experience was positive.

There's no way I'd spend the money retrofitting such a marginal scuba tank though.