This is the 40 cubic foot oxygen tank. It's only about 2 feet tall and six inches in diameter. It's one of the smallest sizes available. This is from an oxy-acetylene rig purchased at a garage sale. It was just lying around tanking up space because it's too old to be refilled legally. Tank safety certification only lasts ten years.
I used an angle grinder with cutting disk to cut the top section of the tank off. The remainder of the tank is 12" and I'll use it to make a crucible for melting metal in. Never cut into a tank unless it has been totally emptied. Oxygen is compressed into the tanks at very high pressures (up to about 1500 PSI) so only empty tanks are safe to cut into. Also I would NOT cut into an acetylene tank!
If this were a propane tank I'd have been able to remove the valve fairly easily. But on oxygen tanks (or at least this one) it was entirely too tightly screwed in so I had to cut the tanks neck off to remove the valve. It's a nice chunk of yellow brass for my foundry!
In this photo I'm welding the tube section of the funnel. I'm using black steel water pipe for this purpose. This photo was taken with the camera on a tripod using the automatic timer. It is not safe to manually photograph a welding arc
Here is the finished basic funnel. I might add a handle, hanging strap or other feature(s) to it in the future.
Here's another view. 1" pipe was used at the base of the funnel because that matches the hole in the tank section. Then I continued it with 3/4" pipe so it will fit into smaller openings.
Here is a view of it from the inside. Notice how thick the walls are, about the same thickness as the steel water pipe. This thing is nearly two pounds of liquid channeling power.
In this photo I'm topping off the oil level on my foundry with some used motor oil. A piece of window screen in the funnel filters the oil quite nicely for the burner. The funnel's size is lovely for easy pouring.
I decided to weld a handle onto the funnel. It makes it a lot easier to work with.