“The gates have to shut extraordinarily fast in order to be effective, and on large ducts it generally isn’t feasible because most gates are neither strong enough nor fast enough for explosion isolation. The ones that are tend to be very expensive,” says Grandaw.
Venting also plays an integral role by providing the needed area to effectively expel the pressure expected to be produced by the combustion based on the properties of the material and the strength of the enclosure, building or vessel.
“If there is an explosion in a dust collector or a bin, the deflagration may propagate back up the duct in the opposite direction of the normal material flow,” FLAMEX’s Wagoner says. “Backdraft dampers can be installed in the ductwork to arrest this propagation to protect work areas located upstream. This causes the pressure of the explosion to be properly vented out of the explosion vents in the dust collector.”