What do our fire protection engineers do in their spare time? Dale Hansen, one of the Principals of our firm, recently developed a combustible dust demonstration apparatus. The demonstration unit is designed to disperse a quantity of combustible dust into the polycarbonate chamber, creating an explosible dust cloud using compressed air. When the cloud contacts the red-hot resistance coils of the cone heater, it will ignite, causing a deflagration within the chamber, building pressure until the explosion vent panel (using layers of aluminum foil) ruptures at the top of the chamber, venting the explosion upwards. The clear polycarbonate construction will allow observers to see the dust cloud dispersion, ignition, and the propagation of the flame within the box and as it ejects through the vent at the top.
The ½-in thick polycarbonate panels can withstand an internal pressure of at least 25 psi (using a safety factor of 2). The size of the chamber and vent opening provided are estimated to create a worst-case reduced explosion pressure (conservatively assuming any St-1 class dust is used) of less than 10 psi.
Here are some more stats for the dust explosion demonstration apparatus:
- Approximately 1 ft3 volume
- ½-in polycarbonate panel construction on ¾-in plywood base
- 7” x 8.5” explosion vent opening with hold-down frame
- High-pressure dust dispersion system with 24V solenoid valve and remote activation switch (uses either 24VDC transformer or three 9V batteries)
- 120V/400W electric resistance coil cone heater ignition source
Check out these videos of the combustible dust demonstration apparatus in action. The first is a shorter video shot in slow motion. The second is a longer video that includes some set up. And, please remember – DO NOT try this at home!