... 3,Oil, Acid, Alkai & high temperature Resistant PVC ducting, air duct, air ducting, flexible duct, ventilation duct1,Material: PVC flam-resistant ... as 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 ...