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 the bottom (bottle neck) of cylinder and the gas is pushed to the top (bottom of the cylinder).  This will force the liquid to leak in to the water and the pockets of water will trap the liquid and only prevent the mercaptan (the odorant) be release to the air.  With propane being heavier than air, the product will stay to the bottom and there will be no chances of explosion and no other actions are needed since the cylinder will be empty after some time.

I would like to get people's opinions on this procedure.  I've called the state Haz-Mat bureau to get their thoughts on this.  Their response was they don't teach nor condone this practice since the liquid won't be suppressed by the water and still have a chance of an explosion from the vapors being released from the water/cylinder.  Your opinons matter in this in helping to clarify the safety of this procedure.

Thank you and keep safe!