A fuel cell system that employs a purge valve, an accumulator and a bleed
valve for selectively purging and bleeding anode exhaust gas. When the
purge valve is opened, the anode exhaust gas purges to the accumulator
where it is collected. The bleed valve provides a controlled release of
the anode exhaust gas from the accumulator that allows the concentration
of hydrogen bled from the accumulator to remain below its combustible
limit. In one embodiment, the purged anode exhaust gas is combined with
the cathode exhaust gas and released to atmosphere. In another
embodiment, the purged anode exhaust gas is combined with a cathode input
gas. In another embodiment, the purged anode exhaust gas is combined with
an anode input gas.