- Joined
- Nov 10, 2013
- Messages
- 837
You're missing the direction of the air flow.
The impeller sucks air in from the bottom of the box and out through the chimney. The air comes into the box through the hoses, drops down below the filter bags and then through the bags (going from the outside of the bags to the inside), then through the flat HEPA filter. The filtered air then passes through the impeller and out the top of the chimney.
People naturally assume that filter bags do their work from the inside out, filling up the bags with debris. (This is true for liquids for the most part.) For this application the long bags provide lots of surface area for air movement. The original Torrit unit I took the design from also had a foot activated "filter shaker" that was a pedal outside the box attached to a cross bar that went through the box attached to the bottoms of the bags. When the unit started lagging in efficiency you'd stomp the pedal a couple times to shake the grinding fines off the outside of the bags. The fines would then be caught in the pan at the bottom of the box.
The impeller sucks air in from the bottom of the box and out through the chimney. The air comes into the box through the hoses, drops down below the filter bags and then through the bags (going from the outside of the bags to the inside), then through the flat HEPA filter. The filtered air then passes through the impeller and out the top of the chimney.
People naturally assume that filter bags do their work from the inside out, filling up the bags with debris. (This is true for liquids for the most part.) For this application the long bags provide lots of surface area for air movement. The original Torrit unit I took the design from also had a foot activated "filter shaker" that was a pedal outside the box attached to a cross bar that went through the box attached to the bottoms of the bags. When the unit started lagging in efficiency you'd stomp the pedal a couple times to shake the grinding fines off the outside of the bags. The fines would then be caught in the pan at the bottom of the box.