What type of air does the OBIGGS use to replace oxygen in fuel tanks?

The OBIGGS (Onboard Inert Gas Generation System) is designed to enhance the safety of aircraft fuel systems by reducing the risk of fire and explosion. It does this by replacing the oxygen in the fuel tanks with an inert gas, which is essential for preventing combustion.

Inerting fuel tanks primarily involves the use of nitrogen. Nitrogen is an ideal choice because it is abundant in the atmosphere, non-toxic, and does not support combustion. This characteristic makes it effective in reducing the concentration of oxygen in the fuel tanks to a level that is below what is required for combustion to occur.

By replacing oxygen with nitrogen, the OBIGGS system significantly minimizes the possibility of fuel vapor igniting, thus enhancing the aircraft's safety profile during various operational conditions, including during flight and ground operations. This is critical for maintaining airworthiness and protecting both the aircraft and its occupants from fire hazards.