Should I use grounded metal gas cans with portable gen installed permanently?

[Sam 4106]

I believe that I have read that a compartment containing propane tanks must be vented at BOTH the top and bottom. I would guess that would also apply to a compartment containing gasoline. I also remember that there is a formula for determining the minimum size of the vent openings. Perhaps Jack or someone more knowledgeable than I am has that information.
Thanks, Sam 4106

[JackConrad]

    Not sure about vent specs for gasoline, but for propane NFPA requires 1 square inch of vent per 7 lbs. of propane, divided between top and bottom of the compartment. 
    When we still had a gasoline generator we had a metal 25 gallon tank bolted to the floor in what used to be the heater core/AC evaporator compartment on our MC-8. The tank was sealed with the only openings being a supply line to the generator, a fill tube from the vented fill cap on the side of the bus and a vent line from the tank that went through the bottom of the compartment floor. We also installed a small piece of expanded mesh in the floor. With all tank openings sealed from the compartment, the only way fumes could form in the compartment is in the event of a leak in the tank.  Just our way, YMMV.  Jack