... ,CO,HCL,Constituent content As Demand6Welding shielding gas mixturesbalance gas :He or Ar,N2CO2,H2,O2,N2,He,CH4,Ar,Constituent content As ... Demand7Keep fresh gas mixtures N2,CO2,O2,Constituent content As Demand8Calibration gas mixures fro Auto Exhaust Testingbalance gas :N2CO2,CO,C3H8,Constituent ...