Replies

1. 
   PaulReuter | Jan 03, 2003 05:32am | #1

   A fan that size will move a lot of air so you'll need a good sized filter.  I started with the same thing so will give you what I did.  I'm sure there are other methods just as good or maybe even better.:-)

   An air scrubber is just a fan to pull the air through the filters, trapping the dust, & exhausting the clean air back into the room again.  The whole works is contained in a box to support the fan & filters and create a duct to control the airflow.  Physically, it's easier to pull air through the filters then push it, so the outlet of the fan is built into the side of the box.  The fit of the fan outlet should be snug, so it can be sealed to prevent leakage.  Before you start building the box, figure out what kind of filters you're going to use.  Some commercial units use bag type filters,but they are fairly pricy.  Some previous posters on this site have reccommended pleated furnace filters- better then regular furnace filters but still not very adequate.  I use pleated filters 2-3" thick & available in several sizes.  Mine are 2'x2', a2" backed by a 3" with two side by side- 2'x4' filter 5" thick.  I lucked onto mine at a distressed goods sale but try an air handling company or maybe your local HVAC dealer.  The filter fabric is a thick felt-type nonwoven material.  I've had it in use over two years & the few times I've checked, there is no visible dust on the 2nd layer of filter.  Once in a while I'll use the crevice tool on the shopvac to clean out some of the dust cake.  Talk about low maintainence.  But, I digress.

   There are no hard & fast rules on scrubber design, it depends on filter size & how you arrange them.  Mine are side by side but it's built into a wall so that worked best for me.  If you're planning a ceiling hung unit, nothing says you cant put filters on two or three sides of the enclosure.  The unit must be air tight, (see mention above about sealing the air outlet).  Use gasket or weatherstrip around the filters so air can get into the enclosure only by going through the filters.  Allow for maintainence access to the fan & changing the filters when necessary.  Plan your switch placement to make it easy to turn on & off, maybe even a timer.

   I've been very wordy on this, I hope it's been helpful.  Feel free to ask any more specific questions that may arise.  Also, I hope this isn't your only dust control method in your shop.  I have a dust collector and an air scrubber & I wouldn't want to do without either.

   Good luck, and yes, it's worth it.

   Paul

2. 
   jackiechan | Jan 03, 2003 05:54am | #2

   Liberty,

   American Woodworker Magazine, June 2000 - #80 issue is dedicated to dust collection in the shop.  They provide precise plans for a series of shop-built air scrubbers of varying size using blowers like the one you have.  I've used these plans to build a series of units using the blowers from what was once a whole house humidification unit.  (The humidifier was hard wired in the basement, and would send the humidified air through duct work throughout the house.)

   The article doesn't address this, but to make the unit more efficient, build a baffle inside the box that will funnel the air to the intake.  On the outside of the box, attach a piece of the washable static filter material over the exhaust port.  This will defuse the exhaust blast of air, as well as catch any residual particles that may have been missed by the filters.

   The debate always is where to place the units.  I have a large scrubber on the floor mounted on small casters for the settling dust, and smaller ones strategically placed up in the ceiling joists.  They are surprisingly quiet, and really get the job done.

   Dan Kornfeld, President/Owner - Odyssey Wood Design, Inc.