... cylinder pakage or packed according to demand Name: helium gasPurity: 99.9~99.999%Property: colourless, odourless, non-flammable, non-reactive, inert ... Name Specification Impurity content (ppm)Carry out Standard Helium(H2) 99.99% O2 +Ar≤3,N2 ≤60,CO≤5,CO2 ≤5,CH4 ... ≤1,CH4 ≤1,H2 O≤3 GB/T 7445-1995 99.9999% O2 +Ar≤0.2,N2 ≤0.4,CO≤0.1 ...