How do the Belfab systems blow out shavings while keeping shop air- heat/AC - in the shop?

What I like about my system is that a rotary air lock is not needed. The air tight collection bin serves that purpose, and allows the air to be returned thru the filters into the shop.

What I don't likes that it has be air tight. The outdoor access door is weather stripped and closed with De StayCo camps to seal 100%. Any leaks weaken performance on the collection ends.

If the collection bin can be located above a trailer/dumpster, it would be simple to have a dump door to load the hauling vehicle.

I don't know Joes system specifically but I know the concept.

The difference between a belfab system and a Cyclone is that the bottom of the cyclone is under vacuum, you need that sealed with a rotary airlock or you create a big vacuum leak.

The belfab is under pressure (it's the filter side) so you can blow/suck dust out one end of the v portion and and return it to the other. Its a closed loop no air is exhausted from the building.

The air could change temperature, but it is not lost.

As Bill said a little different concept. It is a closed loop system with the trailer airtight more or less. Not much heat is lost. The interesting thing is you can create negative or positive pressure in the system by adjusting blast gates at the closed loop outlet and the return inlet. I need to adjust mine a ltiile as I see the trailer puffing a little dust after we shake the bags. It’s almost magical the way the shavings layer into the trailer. When the doors are opened when dumping the layers of different wood species is always interesting.

Because they use the two 7.5hp fans this probably costs more to run than a RAL closed loop. We don’t run them all the time though. This was the only solution I could find at the time for low headroom indoor DC. Over all I am pretty happy with the unit.

That seems a pretty good solution.

Joe I was looking at blowing dust and chip into a dumpster. Do you feel the dust packs? I am wondering if you get more volume then if it was just dropped in.

It does pack Bill. Not sure if Its the weight of the shavings on top or if the transfer fans pack it in. When I open the back doors of the trailer nothing moves till we tilt the trailer up to dump. And have to tilt it to the max. We had to line the floor and partway up the sides with melamine to get the load to slide out.

I also like the layering. A sort of wood based geology. The photo has Maple and Mahogany, then Cherry and Poplar, going back in time. The access door - actually a Dutch door - to the collection 'room' on the side of the shop can be seen. The upper half can be opened for inspection. The lower half opens to expose the older shavings. With the ever-hopeful weatherstrip to keep it airtight. The fan and duct can be seen in the top of the room.

My son often enjoyed seeing the layers when he was much younger. Once, he carefully opened the door and put one of his plastic dinosaurs in the lower layers right at the door, and closed it up. When I opened it - there it was, a brontosaurus laying in the ancient layers of - dust.

View higher quality, full size image (1350 X 1800)

From looking at Dave’s picture I would say the shavings pack tighter in the closed loop trailer. Mine look all the way up like his does at the bottom.

We built a plywood box on top of a single axle dump trailer. Trying to get more capacity I made the box taller than I should have and it can be a little spooky to dump. When I used the 1/2 ton truck it will lift the rear wheels off the ground when dumping. 3/4 ton truck no problem.
If doing this again tandem axle trailer would be better.

View higher quality, full size image (2713 X 3616)

View higher quality, full size image (2875 X 3834)

This photo is of a larger system for a 6-8 man shop. We had a RAL just above the dumpster with a skirt to keep the fines in the dumpster. We had two dumpsters (6x6x6), and could swap them out. Trash hauler picked them up since we could not find a local outlet. The cyclone, fan and filters can be seen on the deck. The 12 filter socks fit into a plywood box below that had a cleanup function for the dropped out filter cake. I don't recall the CFM, but it was 18 HP on the motor, and about 2 HP for the rotary air lock.

This system worked very well. If doing it again, I would build a room around all of it to contain the fines. A wide belt, a four head Quattromat and a lot of Honduras Mahogany made for huge amounts of super fine pink dust all over the collection deck. The local fire inspection people did not want us to do it here without a lot of FR wallboard everywhere.

View higher quality, full size image (1800 X 1350)

One thing to note. You are not supposed to have an indoor dust collector hooked to a widebelt sander. It is a recommendation not a regulation.

David, it that a muffler on the inbound side of the cyclone?

Yes, that is a muffler. I have no idea if it worked. Dust collectors are noisy. That's why I put one in its own room away from the shop.

We wanted that system outdoors for all sorts of reasons, but the town changed their mind on placement and it just was too much to fight.

I had a similar collector setup and it was loud. I tried to get a muffler on the dirty side and the company would not sell it to me, they said it could clog and not work over time. In hindsight I don't think it would have helped. The noise is generated on the output side of the system.

This is a photo of our main collector, it was not quite done when the photo was taken. A dumpster sits under it and the dust drops in from the airlock.

Without the two mufflers shown it was like there was a jet engine running in the shop. It was over 90db I do not recall the exact measurement. With the mufflers it is MUCH quieter, in the low 70's. The muffler is like a large glass pack car muffler. It doesn't really make sense that it works but it does.

View larger image

We put a muffler on a Murphy Rodgers baghouse we had before we put in the Belfab system. It was a outside collector but pretty loud with the return air. The muffler made a big difference.
The Belfab unit has an upgraded fan that is not as loud as the MR unit. I forget what they call it. The transfer fans are pretty loud though but we don't run those a lot.