So I built a shop vac system to move coal from bin to Keystoker boiler hopper. I have placed dust cyclones in line with the vaccums. It works well. I'm intersted in covering the coal hopper for the final measure of dust containment. I am no tin banger. Just wonder what others have used. The set up is identical to what Wiz has shown in his video. A 3 inch fitting out the bottom of the barrel with a can lid dump valve. I would need to open a door to look into it and keep coal particles out of the lid for suction integrity. I have never had a hopper fire but combustability is a concern I'd say. What do you guys use?