I'm thinking about upgrading my dust collection system. I currently blow all my shavings directly into a small box trailer. The system is made up of a 5hp blower outputting directly to the trailer (which is located behind my building). This works well in terms of not having to deal with shavings and filtration bags, but of course draws the air out of the shop. In the summer this draws in hot air and in the winter draws out the heat and pulls in outside cold air. Of course there's the shavings mess around the trailer from blow-by.
I'm thinking it's time to set up a bag collection system, sort of a mini baghouse. I want to keep the existing blower and exit pipe. Instead of directing it to the trailer though I would direct it to the filter and collection bags. I have a good semi-enclosed area on the side of the building that will work well for this purpose. I can completely close it in and make a furnace style filtered opening back into the main shop for the air return.
I'm picturing something that looks like the collectors with the fabric filter bags extending above an inlet manifold, and perhaps 30-50 gallon range clear plastic bags below collecting the shavings. There would be a line of perhaps four collection bags with filter bags above. These units can of course be purchased complete with blowers, but I want to keep the existing blower in place. So, can anyone give me guidance on this type of setup? I have an additional limitation of ceiling height though that is around 7 1/2 to 8 feet max.
(Dust Collection and Safety Equipment Forum)
From contributor J:
I believe you if you say such arrangements are commercially available, but it seems doubtful that plastic bags would last long under the pressure of a 5hp blower. I'm more familiar with smaller systems, and the ones I've seen have fabric bags above and below. What about mounting a cyclone with one of those motorized vacuum-lock thingies (the proper term escapes me) outside, over the trailer, so you don't have to futz with emptying the bags all the time, and ducting the exhaust back into the shop, with only a fine filter (bag or pleated) inside?
Another thing you should at least look into would be canister filters. I put one on one of my units and it makes a drastic difference in suction, as well as taking up less room height wise. You have an advantage as there are far fewer shops looking for the bigger 3-4 bag units. My smaller unit days are almost over though. I just picked up a 7-1/2 hp Torit cyclone with 3 stage after-filter. I expect to be breathing a lot less dust in the near future.
The first system blew all the shavings through a cyclone and then they dropped into a 4' x 4' x 7' airtight room, with the return air going to the shop thru filter socks in a manifold, tucked up in the gable of the shop. The airtight room is accessed from the outside, and the shavings flow out the opened door at pickup truck height.
The next shop had a much larger airtight room, with an auger at the bottom to convey the shavings up into a dumpster. The airtight room was hardly airtight, and required constant resealing to keep up the pressure. If the pressure dropped too much, the dust and shavings did not fall into the airtight room but passed into the filter socks, filing them - no fun.
In our new shop, we are done with the airtight enclosures and will use a rotary airlock positioned over an eight yard dumpster. The airlock will dribble shavings into the dumpster by gravity, and the dust will be minimized. The filter socks will all be reused, and the system will maintain pressure due to the rotary airlock.
If so I may have to look into adding one to my system. My biggest concern is emptying (and keeping airtight) the 50 gallon drum that comes with it constantly. Did Oneida help you with the airlock configuration or did someone else?
The RAL is an expensive bugger, heavy, and has its own motor. But this way we do not have to have the receptacle airtight. The shavings drop at a slow speed into the dumpster. We think the low velocity and no pressure will be clean and dust free. If we have to, we can enclose with walls and a tarp cover. I got the RAL through Oneida, and they have tech help. The RAL is little known in smaller shops, and with its expense, little used. It can eliminate the need for airtight enclosures. The nicely engineered system running smoothly but dumping into a 55 gal drum was all wrong in my mind. We'd spend way too much time moving drums around - then you have to dump them, right?