The 300°C threshold is taken from ISO/IEC 80079-20-1:2017,
where the maximum surface temperature is set to 450°C for Hydrogen and
LNG and 300°C for methyl/ethyl alcohol and LPG. To ensure safe operation
of fuel cell power systems regardless of the fuel cell and fuel type,
these guidelines refer to the lowest threshold for the relevant fuels
mentioned in the ISO/IEC 80079-20-1:2017, that is 300°C.