Helium he Rare gases Cas no.: 7440-59-7 Einecs no.: 231-168-5 Un no.: un1046 Purity: 99.999%-99.9999% Dot class: 2.2 Appearance: colorless Grade standard: electron grade, industrial grade Cryogenic cooling use: Helium gas widely used in maglev train and medical nuclear magnetic resonance (nmr) imaging equipment. Ballon use: Inflat for ballon for brithday party or celebration or inflat for airship. Check analyse: Helium gas widely used in vaccum leak detection such as helium mass spectrometer leak detector. Shielding gas: Helium often used as magnesium, zirconium and aluminium, titanium and other metals welding protective gas.