"litteratuer" takenonotice@all wrote in message
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"Leon" wrote in message
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Vapor literally does not exist with out air, vapor is simply difused
matter suspended in air.

It might seem so, but that is not the case.

Gasoline vapor is heavier than air. With air given a vapor density of 1,
the vapor density of gasoline is between 3 and 4.

In an undisturbed tank, vented to the outside, as gasoline evaporates, the
vapor will displace the air.
In the case where all of the gasoline has been drained and air has entered
the tank, the remaining vapor will be concentrated at the bottom.


Disturbed, I suspect that a shaken tank would not qualify as undisturbed.
There is an awful lot of shoshing around going on in there when the vehicle
is moving and if there is a hole in the bottom of the tank from a damaging
impact the vapors will "grain out" after the fuel.