Why fuel tanks are pressurized in aircrafts?

Question

Why fuel tanks are pressurized in aircrafts?

Answer 1

My guess would be the change in atmospheric pressure that high up would mess it up somehow.

Answer 2

At high altitudes the outside air pressure is very low, near a vacuum. Tank pressurization counteracts fuel vaporization and ensures flow to the engines.

Answer 3

The aircraft fuel tanks are vented with ram air on large aircraft. Ram air can easily be explained. When driving in down the motorway and you open your windo this is ram air. This is vented into the fuel tank so that when fuel is consumed during flight the feul will stay at the bottom of the tank.

Answer 4

only when drained and removed to test for leaks.

Answer 5

There NOT. Actually they have vents to prevent suction from forming when the fuel is poured out of the tank. Because of the vents, air can replace the space taken by the fuel.

Answer 6

Depending on what type of plane you are talking about...the venting systems work the same on all....but in a different way..Example: The Hawker has NACA Vents in the wings to help keep "Positive" Pressure on the fuel. This is the pressurization you are asking about...Basically called top pressure...it allows the fuel to flow evenly and smoothly to the engines...If not for venting (replacing the fuel with air in the wing) the wings could possibly collapse from the suction.

I have seen this happen on a single engine grumman tiger....the right wing vent clogged...and within an hour after switching between the tanks...the pilot collapsed the wing...no crash....but alot of embarassment....hope this helps

Jonathan S

ATP-LRJET,HS-125

CFI/AGI

Answer 7

They are not pressurized in most airplanes.

Answer 8

so the plane can fly

Answer 9

Aircraft fuel tanks ARE NOT pressurized. They are vented to the atmosphere at all times. Holding fuel under pressure would just encourage more fuel leaks, and require a stronger (heavier) structure to maintain the tanks.  

Fuel is moved out of the tanks to the engines by electric fuel pumps.

Answer 10

They aren't.

Airflow is allowed into ant out of the tank freely through the use of something called a NACA scoop, which is really just a vent that allows air to flow in and out to equalize pressure.  If the tanks were to develop a lower pressure inside, they would not be able to supply fuel to the engine.

Answer 11

may be to carry more fuel

Answer 12

a

Answer 13

To confuse matters more, there are some aircraft, (mostly military and some large commercial) that have a Nitrogen gas backfill system.(NGS)  this is to insure that in the event of a puncture (read bullet) or other static charge issues, that no spark could create a fire/explosion.

Hamilton Sundstrand has been making these for B52's an most recently the next generation Boeing 7E7  

http://www.prnewswire.com/cgi-bin/storie...

it uses a combination of N2 pressurization and fuel vapor recycle and Venting.

and most military, that doesnt have a serious weight issue, carries extra N2 for just this purpose

sorry boys....

Answer 14

low pressure and low temperature generate parafin wax from kerosene.

engine would stop working

Answer 15

so more fuel can be put in

and it keeps it more efficient