... Oil, Acid, Alkai & high temperature Resistant flexible duct:/air duct/exhaust duct,ventilating duct,flex duct 1,Material: PVC flam-resistant static-free fabric ... tunnel, basement, ship building or welding, laboratory ,air-conditioner,engine room, the municipal conduct engineering,fire-fighting ... to ventilate or exhaust waste air,dust to supply fresh air.keep more savely and effectively during ...