... Name:helium gas Purity:99.9-99.999% Packing:200bar or 150bar cylinder pakage or packed according to demand Name: helium gasPurity: 99.9~99.999%Property: colourless ... Name Specification Impurity content (ppm)Carry out Standard Helium(H2) 99.99% O2 +Ar≤3,N2 ≤60,CO≤5,CO2 ≤5, ... CH4 ≤10,H2 O≤30 GB/T 7445-1995 99.999% O2 +Ar≤1,N2 ≤5,CO≤1,CO2 ... ≤1,CH4 ≤1,H2 O≤3 GB/T 7445-1995 99.9999% O2 +Ar≤0.2,N2 ≤0.4,CO≤ ...