| 摘要 |
A ventilation tube (20,120,220) is disclosed. The ventilation tube (20,120,220) comprises an inner wall <B>(22,122,222)</B> that defines a fluid passageway for ventilation gases, an outer wall (24,124,224) that surrounds the inner wall (22,122,222) and has a greater thickness than the inner wall (22,122,222), a helical separator member (26,126,226) interposed between the inner and outer walls (22,122,222,24,124,224) so as to define an insulation chamber between the inner and outer walls (22,122,222,24,124, 224), and a heating element (28,128,228) disposed within the insulation chamber. |
