7241 Piped systems for flammable gases and gas mixtures for laboratory, industrial and commercial use (0) Piped systems for the distribution to user points of flammable gases, including liquefied petroleum gas, propane, acetylene, hydrogen and gas mixtures for laboratory, industrial and commercial use 7242 Piped systems for oxidizing gases for laboratory, industrial and commercial use (0) Piped supply systems to distribute oxygen and other oxidizing gases to all user points from the supply source (vacuum insulated evaporator, cylinder manifold, oxygen generator or individual cylinders) 7243 Piped systems for non-flammable gases and gas mixtures for laboratory, industrial and commercial use (0) Piped supply systems to distribute nitrogen, carbon dioxide, argon and other non-flammable gases and gas mixtures from the supply source to all user points 7244 Piped bactericidal, insecticidal, fungicidal, deodorizing and aromatic gas systems (0) Piped systems to distribute bactericidal, insecticidal, fungicidal, deodorizing, aromatic and similar gases from the supply source to all user points 7245 Piped compressed air systems for laboratory, industrial and commercial use (0) Systems to distribute compressed air for laboratory, commercial and industrial use to all user points 7246 Piped vacuum systems for laboratory, industrial and commercial use (0) Piped systems to make suction available at all user points