... duct 1,fire-retardant PVC material 2,competitive price,fine quality 3,Oil, Acid, Alkai & high temperature Resistant 1,Material: PVC ... environment such as tunnel, basement, ship building or welding, laboratory ,air-conditioner,engine room, the municipal conduct engineering,fire-fighting to ventilate ... can conveniently connect to the portable ventilator to use together. air conditioner duct