Gas requirements, 10 Gases for packed columns, 10 Gases for capillary columns, 11 Gas purity, 12 The gas plumbing, 13 Supply tubing for carrier and detector gases, 14 Two-stage pressure regulators, 15 Traps, 16 Cryogenic cooling requirements, 17 Choosing a coolant, 17 Using carbon dioxide, 18 Using liquid nitrogen, 20 Supplying valve actuator