Lake Health and Propane

I was paddling tonight on my home lake which is about 350 acres. I saw a local fuel company truck parked outside one of the houses on the lake and the fuel guy running a hose from somewhere near the house down to the lake. I asked what he was doing and he said trying to bleed off vapor, so I asked “gas vapor” and he said yes. It appeared that he put the end of the hose into the lake as they were bleeding off the vapor.

My guess is that somehow it is safer or stinks less to bleed it into the water, but was wondering if there could be any negative impacts to the lake. This company services a lot of houses on the lake and if there are negative consequences I want to make sure the practice is stopped.

Thanks in advance.

i’ll start the thinking out loud process
propane is very similar to methane right? OK, if it is a natural or manmade lake then a certain huge amount of decaying vegetation lies under the water constantly giving off methane…there is only one carbon difference in the chain so my best guess is that the bleeding off is inconsequential. I also live on one of those little lakes of around 1.5 miles long and many of us there also heat with propane but I’ve never seen our delivery man use the process you describe…but I think I can guess why, propane in the liquid state is like -40F and can instantly freeze skin or eyes, bleeding into the water is probably a safe way.

Thoughts on Temperature

– Last Updated: Jan-16-07 1:14 AM EST –

You say propane in the liquid state is around -40 degrees F, but liquid propane can easily exist at room temperature, or even at the temperature of a very hot summer day (just shake a warm propane tank and feel the liquid swirl around in there if you don't believe that). It stays liquid because it's under pressure, not because it's cold. However, once vented, and the pressure drops to atmopheric pressure, the temperature will drop sharply as the material changes from a liquid to a gas (the temperature change is proportional to the change in energy state during the phase change). Suddenly reduce the pressure of any gas (and it's the gas at the top of the tank, above the liquid, that is escaping), and the temperature drops, but if you add to that the phase change of liquid to gas as occurs when propane escapes the tank tank, the temperature drop is extreme (this phase and temperature change occurs to the material while it's still inside the tank, which is why a tank from which gas is being vented (or used) becomes very cold). So you are correct that what's coming out the vent is extremely cold, just not quite for the reason you state.

I wonder if the propane bubbles to the surface of the water during this venting, or if most of it immediately disolves in water. If it dissolves in water, I'd guess venting it that way reduces the fire hazard. If not, your idea about avoiding accidental contact with such cold material may be the reason.

While it propably doesn’t do any harm
the gas probably just bubbles into the air.

There is no way this practice can be legal. Call the EPA or state DEP and let them deal with it.


Sections 6, 12, and 15 seem to answer the questions for me…

Bad idea
Sounds like a good way to have a highly flamable cloud of gas settle over the water.