SPAN GAS FOR MARINE GAS DETECTOR FASTCALGAS UN1956 Compressed gas , n.o.s ( Oxygen, Nitrogen Mixture) /  Gas composition : Hydrogen sulphide 50 ppm , Carbon Monoxide 500 ppm, Methane 2.2%, Oxygen 18% ,  Nitorgen balance.              Minor component(s) certified to be +/-5%                                                   C: 1.7 Contents: 1.7 Ltr, 8AL 500psi         NA..NA.FCG21222