You do not seem to understand the fact that an environment of pure fuel will not ignite. There are 3 items necessary for a fire. Fuel, air and an ignition source. The mixture of the fuel and air have to be between the lower explosive level (LEL)and the upper explosive level(UEL) (a measure of the amount of amount of fuel in the air expressed as a percentage)
When a truck is full of gasoline, it has a 100% ratio, which is to high for combustion.
True, adding air to the tank truck does not increase the pressure on the truck (DUH< BONEHEAD< I NEVER SAID IT DID)but will allow a certain portion of the gasoline to evaporate into the air and become within the LEL and UEL, and become an explosive mixture. Agitation will allow the vapor to more readily mix in the air to acheive the level necessary for combustion. The containment of the tanker will allow a pressure increase once the gaseous mixture is ignited.
Enough educating the uneducated.
We all understand that it takes air to make a fire. Even you.
Every truck going down the road with propane, or gasoline, or drip gas, or ethane, or ethanol or whatever in it has a pressure inside that is greater than the outside of the truck. That is the nature of these products. Even the radiator on your car has a pressure that is greater than the outside of it because the water is nearing it's boiling point. If you add air to the truck, you add an a component that is pressureless unless compressed. A component that is not exceeding it's boiling point. I agree you make the truck "more likely" to explode. But it doesn't change the pressure inside the truck. And there is no such thing as "adjetating fuel into the air". If you think there is... then just go on ebay and buy a "fuel to air agitator" :)