On-board fuel inerting system

The system of claim 5 wherein the on-board inerting system is aboard an aircraft and wherein oxygen partial pressure probe is maintained in a receptacle capable of being maintained at substantially uniform temperature throughout a flight of the aircraft.

An on-board fuel inerting system for an aircraft subject to electrical sparking or other intrusion of potentially explosive occurrences within a fuel tank of the aircraft which comprises:

• (a) an oxygen partial pressure detector maintained in contact with the vapors in the tillage of the fuel tank;
• (b) a source of inert gas maintained on-board the vehicle in valved communication with the ullage volume of the fuel tank;
• and (c) a controller responsive to the detection of a partial pressure of oxygen within said ullage volume that is higher than a predetermined level to cause inert gas to flow into the ullage volume from said source to establish the oxygen partial pressure in said volume at a lower level.

The system of claim 10 including (d) a uniform temperature receptacle surrounding the portion of the fiberoptic probe in contact with said ullage volume to stabilize the temperature of the probe at a substantially constant temperature throughout a flight.

The system of claim 11 wherein the uniform temperature receptacle surrounds the oxygen-measuring region of the probe to create a volume of relatively constant temperature.

The system of claim 13 wherein the oxygen-measuring region of said probe is surrounded by a guard that permits entry of vapor in the ullage volume to exist in proximity to the oxygen-measuring region of the probe, but protects the probe from contact with liquid fuel within the tank.

An on-board fuel inerting system for the center wing fuel tank of a commercial aircraft subject to electrical sparking or other intrusion of potentially explosive occurrences within that fuel tank which comprises:

• (a) an oxygen partial pressure detector maintained in contact with the vapors in the ullage of the fuel tank;
• (b) a source of liquid nitrogen gas maintained on-board the vehicle in valved communication with the ullage volume of the fuel tank, said source containing an amount of gas sufficient double the amount needed to flood the ullage of said fuel tank;
• and (c) a controller responsive to the detection of a partial pressure of oxygen within said ullage volume that is higher than the proportion that would support combustion to cause inert gas to flow into the ullage volume from said source to establish the oxygen partial pressure in said volume at a lower level.