text: In a typical system supply air enters the thousands of hollow fibres of the membrane at one end, and oxygen preferentially permeates the fibre walls, leaving mostly nitrogen at the discharge end, which is vented from the system as waste.Pressure swing adsorption requires relatively complex equipment, otherwise the advantages are similar to membrane separation. PSA is a technology used to separate gases from a mixture under pressure according to the molecular characteristics and affinity for an adsorbent material of the gases at near-ambient temperatures. Specific adsorbent materials are used as a trap, preferentially adsorbing the target gases at high pressure. The process then swings to low pressure to desorb the adsorbed material and flush the adsorbent container so that it can be reused. Cylinder markings to identify contents
  Any diving cylinder containing a blend of gasses other than standard air is required by most diver training organizations, and some national governments, to be clearly marked to indicate the current gas mixture. In practice it is common to use a printed adhesive label to indicate the type of gas (in this case nitrox), and to add a temporary label to specify the analysis of the current mix. 