Question
We have a 3000 square foot shop with a CNC and other table saws and such. The CNC has its own dedicated outdoor dust collector. All other saws are hooked up to another outdoor dust collector. The fine dust is the problem. Sneezing and coughing is a daily occurrence. What are your shops using for a filtration or purification of the air in the shop? Does anyone have any recommendations? Pushing the dust outside with fans is a no-no with the DNR so that won't work.
Forum Responses
(Business and Management Forum)
From contributor F:
I have three ceiling mounted air cleaners for filtering air in my 1700 square foot shop. Dust collection is a must, but it doesn't do anything for residual dust in your air. For that you need to have active air cleaners working. I have a bigger JDS unit though they are a bit noisy. Due to the noise I only put them on when I need them. I also have one smaller JET collector that runs all day every day regardless. All three units use off-the-shelf filters you can buy at the local Borg or hardware store.
I have to assume if you’re replacing your air you’re just dumping everything outside (no filters). Nice if you can do it, but the original questioner cannot, plus at least 1/3 to 1/2 the country has to heat their shops in winter, so another reason it's probably not a great solution in general. Not sure the average fabric bags on dust collectors collect as fine as a half decent furnace filter or not? I do know with my bags (Beane fabric) there's always a faint plume of dust when I fire it up. There's more than one way to skin a cat so if it works for you great. I just don't see it being practical to use a dust collector as a shops air filtration for most shops.
Secondly, maximize the suction you have - sealed fittings and tight fitting blast gates. No long runs of corrugated hose or no tight radius elbows. It’s smooth, easy and tight. Just a few leaks here and there can cut efficiency a bunch.
Next you have to drop the dust out of the airstream with a cyclone - or two in your case. This has to be sized to the CFM of the fan and ductwork. Then, you need to filter the air. I know nothing about cartridge filters, but have a lot of experience with socks or bags. Make sure they are effective and have additional capacity so the air can move through them back into your shop. Shake them down once or twice a day, or make a timed shaker grate. Some filters like to have some cake on them, others do better with shaking to eliminate it. You may benefit from contacting someone like Oneida Air. Give them a shop layout with the CFM req'd at each machine and let them engineer a system for you. The ones they have done for me are flawless and pay for themselves in better productivity - no unnecessary fiddling with the system at all.
Clean your air as well. It will make for a better environment, more productive and make the shop a pleasant place to be. I moved my collector into a separate room and soundproofed it all so the shop is clean and relatively quiet. Put the DC on a remote control so it is easy to switch on or off.
My collectors are bag type, sometimes with homemade cyclones to take out the chips. I also use a very quiet homemade air cleaner: a 3 Hp radial blower ducted to one end of an oversized filter bag, with a sheetrock bucket band clamped to the other end. It's oversized so superfines aren't pushed through (there is actually no such thing as half micron rated fabric, filtering ability depends on weave, coating and air pressure). There is very little load, which means the blower is very quiet, unlike the collectors. I hit it with a stick every once in a while, but the cake falls off on its own. It is tied up to the ceiling running horizontal so it's out of the way. The bag never needs replacing and only rarely needs to be dropped and the bucket cleaned out— the superfines in the air don't have much volume, just a lot of annoyance.
If you run a blower at low pressure, the motor basically runs at half its max amp rating. For the 3 HP cleaner that's 3-4 KW per hour, and a KW costs me about 8.5¢. On a 40 hour week, if it ran all day it would cost just over $10, but I only run it when I'm sanding. I use a dust mask also, because my lungs are sensitive, and the dust mask costs about what the electricity does. For the comfort, that's a good price.
