SpudFiles

Wow... It's been a while
Well I've been thinking of using an emptied 5lb ABC powder fire extinguisher as a refillable propane tank for one of my creations. I am posting this to ask whether this is safe or not. I know it would be able to handle the pressure initially but I am worried about the material of the extinguisher since I read somewhere that propane should not be used with galvanized steel for whatever reason the author felt too irrelevant to include. I am unsure of what material is used to make ABC fire extinguishers and was hoping one of you would know. So is my idea safe of not?

Look who's still alive

Propane is not a corrosive liquid, I can't think of a reason why it should cause problems...

They are just aluminum cylinders. They are only tested to somewhere between 300 and 360 psi depending on the tank but on a hot day propane can reach pretty high pressures (~250 psi if I recall) so I'd handle with caution... It would be a good idea to pressure test it to at least 300 psi if you have the ability to.

An actual propane tank would be much safer IMO.

Jack-

Surprisingly so

Thanks, I guess I'll continue as planned then

Gun Freak -

They are supposedly tested to 600 psi, but then again they are made in thailand

I was more worried about liquid propane reacting with galvanized steel in some way than the shear pressure alone. Unfortunately, I can't find the mini bernzomatic type propane tanks here.

I guess ABC type FE's are much different over there!

The big problem with home created propane cylinders is they often lack overfill protection and overpressure protection. If filled with cold propane, sealed and carried in a warm car, etc, they are likely to burst due to the expansion. Please use a properly designed cylinder.

In the US it is illegal to transport a non DOT (Department of Transportation) approved cylinder. You can fill it at home, but can't leave home with it on a public road.

Technician1002 wrote:If filled with cold propane, sealed and carried in a warm car, etc, they are likely to burst due to the expansion. Please use a properly designed cylinder.

If you fill a tank to the point where it contains some liquid propane that the temperature at filling is irrelevant, the pressure vs. temperature curve is identical as long as there is some liquid in the tank.

The problem arises when there is insufficient expansion place so all gas space becomes filled with liquid when it warms. This can result in very high pressure. It works in reverse of water in a pipe freezing and breaking the pipe. Here a liquid can expand in a sealed container and destroy the container when it runs out of expansion room.

Propane tanks should never be filled past 80 percent full.

Gotcha. In a 100% liquid filled tank raising the temp gives huge increases in pressure. Even water does it.

But if a tank has sufficient gas space then it isn't nearly as much a problem. Then you just have whatever the gas's partial pressure is at the particular temperature.

This is why BBQ tanks have overfill protection float valves, and disposable tanks are filled by weight and are not refillable, legally anyway. For safety the design must not exceed 80% full by volume to ensure the expansion space for warm weather.