Are old empty oxygen tanks good for a core riser

Hi,

I'm just wondering if I should take 3 oxygen tanks that have been offered to me for free. I would use them as part of the heatriser. This would be used for the outside experiments, and hopefully for the garden bench.

Should I take them and work with them? The RMH for the home will be made with bricks, or even a poured core that I've seen built.

If it's free, take whatever you can. If they can't be used as a heat riser container. They most certainly can be used as flues

How would you cut them?

I looked at them today, they are small. I thought you could flex off the top, but the bottoms have a rim on which the bottle stands in, but its soldered onto it.

A welding shop could easily cut off the top and bottom. I just had a welder friend take off top n bottom on an old 15 gallon propane tank for me. The edges are rough but it won't matter for my project -- a TLUD stove for cooking and biochar production.

The the oxygen tanks were the 'large' size oxygen tanks then they would work. You would need to cut them with an oxygen-acetylene torch. The smaller cylinder you might need to weld together.

It is probably more work than necessary. Using the refractory bricks would be easier.

yeah, I think I'll stick with using the bricks, and wrapping the core with some rockwool batting and chicken wire, which I have enuf of.

Besides, I've never worked much with metals, I would need someone who was all set up to dissect any tank. It looks easy to do, but for someone who has never flexed anything before, and then something so thick, I think I'll leave that to the experts, and be more self sufficient with my bricks and mortar. I've worked with clay and slip before, I've even poured concrete, I'll stick to the more doable.

Thanks for all the input.

> cut tanks...

Sawzall or grinder w/carborumdem blade should work pretty well. The grinder would be easier. Little Makita 4" grinders are so cheap they're practically throw-away and they hold up to abuse and are useful in numerous other ways (smoothing/cleaning CI cookware comes to mind). Harbor Freight version not recommended - breaks too soon to make it worthwhile. Carborundem cutting blades stink (smell) when in use, make lots of black dust and throw sparks when cutting. The other usual caveats apply: Power tools can damage your hearing, blind you and inflict grave damage to other body parts - so wear eye and ear protection and exercise care.

Note: Working propane tanks requires some care not to explode yourself. Many people do it no problem, some die. Read up and talk around b4 tearing into that type of tank.


Rufus

I agree that a sawzall or grinder with a cut off blade are the way to go. Torch cutting usually leaves a sloppy mess that requires as much grinder work as if it were used for the cut. I wear a full face asbestos grade mask to protect eyes, face and lungs. Ear plugs topped with muffs does the ears.

Any explosion hazard from oxygen tanks?
I use "diamond" grinder wheels for almost anything from bricks to stainless, but the potential explosion hazard of various pressure vessels has scared me off from them.

William Bronson wrote: Any explosion hazard from oxygen tanks?
I use "diamond" grinder wheels for almost anything from bricks to stainless, but the potential explosion hazard of various pressure vessels has scared me off from them.

Hi William,

To my knowledge, there is no danger from exlosions if the tank is empty, and the valve is screwed off. I've read that many have used such tanks in the past to build a rocket stove. I've abandoned this idea. I'm going with firebricks that can take up to 1000°C, and wrap the core with rockwool. Less work, since you don't have to fill the core riser, and I won't have to worry that much about my core falling apart.

Diamond grinder wheels are a must in every handyman's workshop, I would say.

May want to do a "hammer ring test" before you start cutting into the tank. Assuming it is a steel cyl (probably a 125cf or "s" size for industrial "m" for medical) the cyl should ring like a bell when struck (usually done with the cyl cap). If it sounds like anything other then a bell the steel may not be in the best of shape. This could be due to rust,water in the cylinder, or I've even seen bondo used to fill in a hole (not cool!). Not that any of these will cause an issue for a heat riser (not sure one way or the other) but it's a simple test that's able to be done quickly before you start cutting into it.

You also may want to do an "odor sniff test" as well. Open the valve on the cyl all the way. Then use shop air to put some positive pressure into the tank (2-3 sec burst of shop air). Waif the gas that comes out toward you & sniff . If the residual air smells musty it means it's been contaminated (usually with water) & likely explains why you have it : ) If it smells like a fuel I trust you know not to proceed with your plan. If you don't have any gas escape then the valve wasn't opened or it may have been damaged. In either case the cyl may still be under pressure & I saved your life. If you smell the same shop air you put into it I'd say leave the valve open (to avoid trapping gases) & your good to go! Remember to take before & after pictures & post them here for all to see.
-PD

Hi Philip,

these oxygen bottles are very small. The man who gave them to me said he used the oxygen for his aquarium. He does it regularly, forgot how often. He seems to have had them for a while. There seems to be some fluid in one of them though.

thank you for your concern, its sweet

As far as pictures are concerned, I will be documenting it all! I'm still in the material gathering phase though, trying to find cheap to free stuff, and see what needs to be bought. So far, it looks like i'm gonna have to buy bricks, rockwool and find the right size barrel.

I'm going with bricks...