EATON CORPORATION OBIGGS UNIT
On-board inert gas generating systems (OBIGGS) are used to significantly reduce or even eliminate the chance that a spark from any source, including lightning, will cause a fuel tank on a plane to explode. The OBIGGS system works by supplying nitrogen extracted from atmospheric air that is continuously flowed/pumped into the plane's fuel tanks. As it is pumped in, the nitrogen dilutes the oxygen that is mixed in with fuel vapor with goal of reducing the percent oxygen available to below a level that will support combustion, usually about 9 percent.
Sizing an OBIGGS unit depends on a number of factors:
1) How big the fuel tanks
2) The amount of air that works its way into the fuel tanks from outside
3) How quickly fuel is burned and open space in the tanks is created
4) How much oxygen is dissolved in the fuel, and how fast that oxygen will released from solution.
Also, poorly shaped fuel thanks could reduce the effectiveness of an OBIGGS installation.