Patent ID: 7127937
Filing Date: 2006-10-31
Classification: H01M,Y02E

Abstract:
1. A method for determining if there is a leak in a fuel cell system, said method comprising: providing a primary shut-off valve in a supply line between a compressed gas tank and a fuel cell stack; providing a secondary shut-off valve in the supply line between the primary shut-off valve and the fuel cell stack; closing the primary shut-off valve at system shut-down; measuring the pressure in the supply line between the primary shut-off valve and the secondary shut-off valve after the primary shut-off valve has been closed; closing the secondary shut-off valve when the pressure in the supply line between the primary shut-off valve and the secondary shut-off valve reaches a predetermined pressure; storing the measured pressure when the secondary shut-off valve is closed; measuring the pressure in the supply line between the primary shut-off valve and the secondary shut-off valve after the measured pressure is stored when the secondary shut-off valve is closed; comparing the stored pressure to the measured pressure; determining that there is a leak is in the secondary shut-off valve of the supply line between the primary shut-off valve and the secondary shut-off valve if the stored pressure is greater than the measured pressure by a predetermined first value; and determining that there is a leak in the primary shut-off valve if the stored pressure is less than the measuring pressure by a predetermined second value.