(EP914685-A1)      A method of operating a PEM (polymer electrolyte membrane) fuel-cell installation (2) having at least one PEM-fuel cell module (4) comprising a hydrogen inlet valve (14) and an oxygen (18) inlet valve, and in which, for switching off the PEM-fuel cell module in a first step, the oxygen inlet valve is closed and, in a second step, the hydrogen inlet valve is closed, at a given partial oxygen pressure at a cathode part of the PEM-fuel cell module (4).    Instead of the oxygen inlet valve (18), an air compressor is used for operating the PEM-fuel cell module (4) with air, and in which the partial oxygen pressure is measured indirectly from the voltage of the PEM-fuel cell module (4).    USE/ADVANTAGE -   For application as current generation source to provide emission-gas-free electrical propulsion of motor vehicles. Low operating temp, long operating life and absence of liquid, corrosive electrolyte.    (US6068942-A)      A method of operating a PEM (polymer electrolyte membrane) fuel-cell installation (2) having at least one PEM-fuel cell module (4) comprising a hydrogen inlet valve (14) and an oxygen (18) inlet valve, and in which, for switching off the PEM-fuel cell module in a first step, the oxygen inlet valve is closed and, in a second step, the hydrogen inlet valve is closed, at a given partial oxygen pressure at a cathode part of the PEM-fuel cell module (4).    Instead of the oxygen inlet valve (18), an air compressor is used for operating the PEM-fuel cell module (4) with air, and in which the partial oxygen pressure is measured indirectly from the voltage of the PEM-fuel cell module (4).    USE/ADVANTAGE -   For application as current generation source to provide emission-gas-free electrical propulsion of motor vehicles. Low operating temp, long operating life and absence of liquid, corrosive electrolyte.    (JP2000512069-W)      A method of operating a PEM (polymer electrolyte membrane) fuel-cell installation (2) having at least one PEM-fuel cell module (4) comprising a hydrogen inlet valve (14) and an oxygen (18) inlet valve, and in which, for switching off the PEM-fuel cell module in a first step, the oxygen inlet valve is closed and, in a second step, the hydrogen inlet valve is closed, at a given partial oxygen pressure at a cathode part of the PEM-fuel cell module (4).    Instead of the oxygen inlet valve (18), an air compressor is used for operating the PEM-fuel cell module (4) with air, and in which the partial oxygen pressure is measured indirectly from the voltage of the PEM-fuel cell module (4).    USE/ADVANTAGE -   For application as current generation source to provide emission-gas-free electrical propulsion of motor vehicles. Low operating temp, long operating life and absence of liquid, corrosive electrolyte.