Does water get rid of propane?

[jemshkoj]

I was using propane for my airsoft gun andi was shooting it near the grass and then i realized propane might of went onto the grass and what if someone lighted a match or something, so my question is will water get rid of it? if not will it just go away eventually, it IS outdoors.

[Nestor]

Propane is heavier than air, so it will have sunk onto your grass, but whatever propane there is will dissipate into the surrounding air so that it's no longer at a flammable concentration.

There are two concentrations that are important to know for flammable gas; the lower explosive limit and the upper explosive limit. The lower explosive limit is the lowest concentration in air that a flammable gas will ignite. Below that limit the heat created by the reaction of that gas with oxygen is largely consumed by heating the air, and so the reaction isn't self sustaining. That is, the gas mixture stops burning by itself.

The upper explosive limit is the concentration at which a gas/air mixture won't burn because there's insufficient oxygen to keep the reaction going. So, for example, if you could somehow strike a match inside a propane tank, the match wouldn't burn because there'd be insufficient oxygen inside that cylinder to keep the combustion going.

In general, Hollywood movies are total science fiction when it comes to flammable gas explosions. That's because the concentration of a flammable gas in the air needed to reach even the lower explosive limit is generally way more than you need to have everyone in that environment disoriented, barfing up their breakfast and even passing out. That is, if you have a gas leak in a building, the people breathing that air/gas mixture are very much more likely to become disoriented and go outside for some fresh air than they are to blow themselves up by lighting a cigarette. And, that's because air is 78 percent nitrogen, and nitrogen doesn't burn. So, getting an explosion by mixing a flammable gas with air is a lot like trying to start a pile of garbage burning if 78 percent of the garbage isn't flammable. It's hard to do because the stuff that doesn't burn is going to absorb the heat heat produced by the stuff that does burn, making it much more difficult to keep the fire going. Kinda like burning wet wood.

But, if there's no air currents and the propane gravitates downward, as it would in an underground parking lot full of propane powered vehicles, say, then you very well could reach the lower explosive limit in the air near the floor and still have an explosion.