... , far advantageous than organic toughened glass air ductand other air duct.(2) Great incombustibility, FRP Ventiduct is compounded by many inorganic ... above 15 years.(5) Low noise, compared to iron sheet duct, there is no low frequency noise in theFRP Ventiduct, to ... 10m/s, 15m/s and 20m/s. FRP ventiduct/ vent duct