Vapor Recovery

Anyone work at a gas station? Gas stations went to great lengths to install “vapor recovery systems”. Yet, the more fumes collected, the higher the pressure in the tank. Eventually, the recovery tank would have to be emptied, etc., etc., etc.

While the concept of vapor recovery is understandabile, various practical problems present themselves. As an answer, someone suggested to me the fumes are returned to the supply tank, but still:

a) Fumes have be drawn off somehow. If there is a prime mover, you think you’d hear a compressor, for example, kicking in, etc.
b) Once collected, how disposed? Is there a service that will condense the fumes back into gasoline?
c) Many of those rubber seals at the nozzle barely mate properly anymore to form a good seal, etc…is this concept of vapor recovery really successful?

Any info would be appreciated.

The vapors generally condense naturally in the cool underground tank. Ya kinda got it backwards. See the pump condenses the liquid some to get it into the hose then when it comes out into the air pressure some vaporises so the recovery system collects the vapor. Some of it condenses almost immediatly especially on cooler days and re-enters the flow right at the nozzle. There is some ‘normal’ evaporation too. But yeh it does seem they are more trouble and expense for the little good they do. and no matter how long you wait there is always a few drops that fall, more than i get on non recovery systems.

“Pardon me while I have a strange interlude.”-Marx

Wait a minute! The pump condenses the liquid? First, these are submersible pumps with a flooded inlet port. Next, pumps don’t work well with vapor pockets in the liquid which can damage pump internals. Lastly, any vapors would actually stay above the liquid level…although I suppose some bubbles may have a short little life near the surface.

I WAG you’re not far off, though. I suppose the vapors can condense if the tank is cooler. Also, it is potentially possible that condensation can occur if the incoming vapors compress the resident vapors. But, it is also possible that conditions can exist in which little vapor recovery actually takes place due to a lack of thermal gradient to condense the vapors. At that point, I guess it’s a question of just how efficient the process is…

Thanks for the insight!