Patent ID: 7581431

Claim:
A gas leak detection device for a fuel cell system comprising a main valve in a fuel gas supply source, comprising: a shutdown valve provided in a fuel gas supply channel downstream of said main valve; a plurality of pressure monitoring devices that each operate within a different predetermined pressure range and monitor a pressure in said fuel gas supply channel between said main valve and said shutdown valve; a depressurization treatment device that depressurizes the inside of said fuel gas supply channel; and a determination device that monitors a variation of pressure in a sealed space of said fuel gas supply channel formed between said main valve and said shutdown valve after said main valve and said shutdown valve have been closed and determines an operation state of said main valve based on the variation of pressure in said sealed space, wherein in said depressurization treatment, said fuel gas supply channel is depressurized until the pressure enters the predetermined pressure range in which the pressure can be monitored in said plurality of pressure monitoring devices.