Patent ID: 7322228

Claim:
A method of evaluating the leaktightness of a device for storing fuel gas under high pressure for use as fuel by vehicles and delivered from a filling station via a filler hose that is connected to the gas storage device, itself comprising pipework and at least one tank, the method comprising the following steps: a) while filling the fuel gas storage device from the filling station, pressurizing the filler hose, the pipework, and said tank from the filling station at a pressure that is greater than at least 5 bar, filling at a controlled filling flow rate Q i , and measuring variation in pressure P i ; and b) at a first predetermined instant t i after the start of pressurizing, suspending the filling operation without depressurizing, continuing to measure variation in pressure P i , to a second predetermined instant t j , comparing the pressure P i relative to a predetermined threshold S i , and if, between the first and second predetermined instants t i , t j , the pressure decreases and drops below the predetermined threshold S i , informing that a leak is present, whereas if, between the first and second predetermined instants t i , t j the pressure remains above the predetermined threshold S i , restarting the filling operation and, at subsequent instants, including at the normal end of the filling operation, repeating verifications of variation in pressure relative to predetermined thresholds during a predetermined duration after each suspension of the filling operation so as to detect, on each occasion, the presence of a leak, if any, wherein, prior to connecting the fuel storage device to the filler hose of the filling station, the method further comprises: pressurizing the filler hose up to a predetermined pressure greater than or equal to 5 bar, suspending pressurization at an instant t 0 i when the predetermined pressure is reached, but without depressurizing, measuring variation in pressure until a second predetermined instant t 0 j , comparing the instantaneous value P i of the pressure relative to a predetermined threshold S 0 i , and, if, between the first and second predetermined instants t 0 i and t 0 j , the pressure decreases and drops below the predetermined threshold S 0 i , then informing that the filling station or the filler hose presents a leak, whereas if, between the first and second predetermined instants t 0 i , t 0 j the pressure remains above the predetermined threshold S 0 i , then repeating the operation of pressurizing the filler hose up to a predetermined pressure greater than the previously-reached pressure, and repeating the operation of suspending pressurization and measuring pressure variation relative to a predetermined threshold during a predetermined duration in order again to detect the presence of a leak, if any, with new operations of pressurization and suspension while monitoring pressure variation being performed until reaching a maximum operating pressure of the filling station.