At the firehouse I work at, the volunteer chief has decided on a procedure to mitigate a leaking 20 lb. propane cylinder.

When you arrive on scene and size up that you have a 20 lb. propane cylinder that's releasing gas from it's burst disc (not a pressure relief that we all think it has).  Next, find a trash can and fill it half way or so with water and turn the cylinder upside down in to the trash can of water.  The theory with doing it this way is that the liquid pushes to…