Fuel tank pressure

[Kudo.GA]

When the tank sack inside it's housing is empty, is it vacuumed. So that when fuel flows in when the car is fueled up, there is no air in the tank? Making the sack only filled with fuel and nothing else, so that in the event of a shunt or crash, the fuel doesn't slosh about in the tank?
Or is the tank exposed to the outside air making the sack pressurized/having to take air out as fuel flows in?
If the sack is pressurized: does this infuence the probabilty of it bursting in a crash when a foreign object tries to penetrate the Kevlar sack?
If they let air in when fueling up: does the sack become negatively pressured when the car is using fuel and emptying the sack, making it deform in the tank's shell? Or is it tightened down that much that it doesn't deform under the force of the fuelpump?
Hope someone can tell me a bit more, I see something in the technical regulations for 2021 saying that you should or shouldn't pressurize the tank. Article 6, p. 49
Doing some research on the fueling in F1 for a college project (automotive engineering, applied sciences).
Thanks a lot, an intrigued student

[hollus]

A few answers here:
https://scarbsf1.wordpress.com/2012/06/ ... el-system/

[saviour stivala]

‘’fuel tank (formula 1) pressure’’. There is no pressure in a formula 1 fuel tank. Fuel is not pressurised/is not under pressure in a formula 1 fuel tank. The fuel tank is designed for internal venting, so that fuel fills and drains the tank without causing pressure variations. What is pressurised and it sites inside the fuel tank is the collector-pot (low pressure).

[saviour stivala]

It should be noted that the ‘scarbs’ formula 1 fuel system article covers formula 1 fuel system up to end of 2013 season/regulations (NA 2.4L V8 engine). This fuelling system was limited to a maximum of ‘indirect fuel injection’ pressure 100 bar, this system used outside of air intake trumpets shower-type injectors and included a fuel return line back to the fuel tank.

[Jolle]

F1 fuel tanks/bladders are still not pressurised and have a breather system to let air in. Altough it sounds safer to have no air, just fuel in the bag, it isn’t. Air is a good cushion for impacts and the tank has several baffles and valves to prevent any slushing around. Also, the bag is very stiff. It takes a couple of ours of cursing to get it in the car for instance.
As for fuel pressure, the low pressure fuel pump (just a few bars) is inside the tank, the high pressure pump is with a it’s own collector tank (Max 2 liter, Will be 0.25 liter) is outside the tank. It’s mostly this two liters that made Grosjean’s fireball.

[ENGINE TUNER]

F1 fuel tanks/bladders are still not pressurised and have a breather system to let air in. Altough it sounds safer to have no air, just fuel in the bag, it isn’t. Air is a good cushion for impacts and the tank has several baffles and valves to prevent any slushing around. Also, the bag is very stiff. It takes a couple of ours of cursing to get it in the car for instance.
As for fuel pressure, the low pressure fuel pump (just a few bars) is inside the tank, the high pressure pump is with a it’s own collector tank (Max 2 liter, Will be 0.25 liter) is outside the tank. It’s mostly this two liters that made Grosjean’s fireball.

Gros fireball was much more than 2L, the side access port into the fuel tank came loose in the impact and much more than 2L burned. The full 100kg did not burn because the fire was starved of oxygen by the extinguishers.

As to the original post, there is a foam inside the tank to minimize sloshing, and fuel is compartmentalized within sections of the fuel tank to also minimize sloshing and maximize car performance.

[saviour stivala]

According to regulations at least up to 2019 the use of foam inside the fuel tank is not mandatory.
Some articles says foam is used. But both ‘scarbsf1’ article ‘’analysis: f1 fuel system’’ as well as ‘racecar engineering’ ‘’technology explained: f1 fuel system’’. Shows a formula one fuel tank cut in half and no foam can be seen. Also no foam use is mentioned in both articles.

[strad]

Also, the bag is very stiff. It takes a couple of ours of cursing to get it in the car for instance.

According to Matchett and Elvis, both it requires the mechanic with strong but small hands.