Vacuum assisted air separation module operation

A fuel tank inerting system comprises:

• an air separation module having an oxygen permeable membrane that separates process air into nitrogen-enriched air and oxygen-enriched air;
• an actuated valve upstream of the air separation module, wherein the actuated valve regulates the flow of process air to the air separation module;
• a variable vacuum source configured to increase a pressure differential across the oxygen permeable membrane by drawing oxygen-enriched air across the oxygen permeable membrane;
• an oxygen sensor in a nitrogen-enriched air line downstream of the air separation module, the oxygen sensor configured to detect a concentration of oxygen in the nitrogen-enriched air;
• an at least one fuel tank, wherein the at least one fuel tank is downstream of the air separation module and the oxygen sensor and is fluidly connected to the air separation module via an inert gas outlet;
• a variable speed motor drive;
• and
• a controller configured to control the variable vacuum source and the variable speed motor drive, based on a concentration of oxygen in the nitrogen-enriched air detected by the oxygen sensor and data from the at least one fuel tank sufficient to adjust the concentration of oxygen in the nitrogen-enriched air, to provide the pressure differential such that a desired purity of the nitrogen-enriched air for fuel tank inerting is produced, wherein the controller is configured to produce nitrogen-enriched air having an oxygen concentration of less than 12% for fuel tank inerting,
• wherein the controller is further configured to adjust the rate of flow of process air through the actuated valve based on the concentration of oxygen in the nitrogen-enriched air detected by the oxygen sensor and data from the at least one fuel tank.