送气管 meaning in English

air feed pipe
induction line

Ventilation for buildings . sheet metal air ducts and fittings with rectangular cross section . dimensions
建筑物通风.矩形截面薄板金属送气管和配件.尺寸
Ventilation for buildings - sheet metal air ducts with rectangular section - requirements for strength and leakage ; german version en 1507 : 2006
建筑物通风.矩形面薄板金属送气管.强度和泄漏要求