920,148. Refrigerating. TRANE CO. Oct. 4, 1961 [Dec. 12, 1960], No. 35814/61. Class 29. In an absorption refrigeration system, non- condensable gases are withdrawn from an auxiliary absorber which is mounted in the main absorber. The low-pressure system shown includes an absorber 14 with an auxiliary absorber 58, a generator 18, eliminators 46, 48, condenser 20 and evaporator 16 all mounted within shell 12. The refrigerant and absorbent may be water and a Solution of a salt such as lithium bromide, lithium chloride or sodium hydroxide. Absorption liquid supplied by spray pipes 30 is distributed over cooling tubes 24 in the main absorber and some of the liquid passes to the auxiliary absorber through holes 66. The absorption of water vapour in the auxiliary absorber produces a pressure differential which causes non-condensable gases plus water vapour to be drawn from the main absorber through the ends 70 and nozzles 72 of collecting tubes 68. The gases are withdrawn through conduit 74, normally closed solenoid check valve 78, oil separating chamber 80 and pump 82 to vent tube 84.