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Beyond dust collection...... filtration

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Forum topic by ncdon posted 04-22-2011 02:19 AM 1837 views 0 times favorited 12 replies Add to Favorites Watch
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ncdon

214 posts in 2341 days


04-22-2011 02:19 AM

http://s1224.photobucket.com/albums/ee377/ncdon/

This monster was delivered to the shop this afternoon. My neighbor is a hvac tech. He knows I’ve been looking for a squirrel cage fan to drive a filtration system in the shop. This fan came from an oil heating system that they replaced with a heat pump recently.
First a couple of facts about the shop then a couple of questions.The shop is a steel building 20 X 30, 600 sq ft.
9 ft walls. I see most filter suspended from the ceiling. In my shop that will be tough to do because of the way the roof trusses are installed. I will have to wall mount the unit and install ducting suspended from the trusses. I’m thinking of running the incoming air duct the length of the building with inlet grates about every 5 ft. , Then to a set of 2 filter built onto the air tight box housing the fan. The first filter will be a disposable, the second a washable. I’ll run that duct close to the middle of the shop. The duct for filtered air exhausted from the fan will return down outside wall also with grates at 5 ft intervals.
The questions Is that a sound plan? Is there an optimal height to place the ducting, particularly the suction side
ducting.
This is a big powerful fan. on high speed it will blow you hat off at 15 feet. It is going to take large ducting. It should really pull a lot of fines out of the air and with the right filter improve the air quality a bunch. Any suggestions on filters will be appreciated.

-- Don, North Carolina,http://www.ncdon.com Working full time at retired.


12 replies so far

View dpjeansonne's profile

dpjeansonne

72 posts in 2679 days


#1 posted 04-22-2011 02:59 AM

I have a 20×30x8h shop and built a filtration unit with a hvac blower. I made the box to fit a 20×20 pleated filters. I have a washable foam filter first to catch the big stuff, then a 3M 600 -700 rating filter that removes dust etc., and the final is 1000 – 1200 rated pollen, fine particle filter. Pick your filter size that is readily available at a good price and make the box fit it.
I mounted the unit up against the ceiling on the long (30ft) wall 1/3 or about 10ft from the short wall. This is the generally recommended position. It is closer to some of my high dust generating equipment.
I run the unit on low or medium speed which seems to be fine.
the rule I heard was you want to have 6-8 air exchanges per hour which works out to 480 – 640cfm. I think any size hvac blower will easily handle that. I think it is best to run as slow as possible to mimize stirring things up and makingh to much draft in the shop.
Most people think that a floor mounted unit doesn’t work as well. If you mount ot wall it needs to be atleast 4 inches from wall.

Hope this helps.

-- Cajun Don, Louisiana

View HerbC's profile

HerbC

1592 posts in 2324 days


#2 posted 04-22-2011 03:31 AM

Don,

I’ve read that positioning the air filtration unit in the middle of one of the long walls, as close to the ceiling as you can get it is better than having it in the middle of the room. The idea is that the unit sets up a flowing loop of air around the room at that level and moves the air better than in the middle of the room…

Good Luck!

Be Careful!

Herb

-- Herb, Florida - Here's why I close most messages with "Be Careful!" http://lumberjocks.com/HerbC/blog/17090

View SteveW's profile

SteveW

392 posts in 2324 days


#3 posted 04-22-2011 05:08 PM

I also used an HVAC blower for one of my dust collectors, but its a free standing unit that has casters on it,
so that I can wheel it around close to my work area.
This one pulls downdraft from the top, and then exhausts through 3 pleated filters at the bottom…
I also have my radio perched atop it while its running,
and it does a good job of clearing the air fast as I work.

-- On the eighth day God was back in His woodworking shop! SteveW

View NBeener's profile

NBeener

4808 posts in 2639 days


#4 posted 04-22-2011 05:15 PM

Here’s an FWW article that may help “clear it up” for you ;-)

http://www.finewoodworking.com/Community/LettersDetail.aspx?id=33664

Also … I have a JDS unit hanging from my (9’) joists, but also have a roll-around DIY box that I seem to turn to even more, these days.

In my shop-built unit, I use a 5” pleated media filter and a 3M filtrete (farthest outboard). Works beautifully.

I also put a “whole house fan” timer on the shop-built box. Makes it very easy to leave it running for a couple of hours, after I leave the shop.

Good luck !

-- -- Neil

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Grandpa

3256 posts in 2141 days


#5 posted 04-22-2011 06:26 PM

I think I read the same article (Fine Woodworking) and it did say to make a loop system using 2 or 3 units if possible. Mount the units close to the ceiling and near the wall. It made sense when I thought about it. I agree that on home built units you have to have readily available filter sizes. At my local ACE hardware store the large and the small filters have the same price tag. I am thinking that larger filters have more filtering media and more surface. I plan to use the large filters.

View NBeener's profile

NBeener

4808 posts in 2639 days


#6 posted 04-22-2011 06:51 PM

And … to Grandpa’s point …. (no shameless plug intended….)......

I built mine BIG. I did that for one reason: I want to be able to use ANY filter, whether my goal is max filtration, minimum price, best value, or … whatever.

http://lumberjocks.com/projects/44817

With mine, I found a BIG difference in air flow between:

The 5” pleated media filter + TWO 3M Filtretes and
The 5” pleated media filter + ONE 3M Filtrete

Which made me glad I built in the flexibility to put as much, or as little, filter in there as I wanted to ;-)

-- -- Neil

View ncdon's profile

ncdon

214 posts in 2341 days


#7 posted 04-22-2011 08:59 PM

Ah, wide awake finally and back to you all.
Don, glad for the practical experience input, good to hear from someone who’s done that. I just got back from Lowes, got a 20 X 20 forever washable and a 3m 1080 disposable. Still working on the ducting. But I can get started on the box.
Herb, I understand the loop idea, it’s got me rethinking.
Steve, I like the portable unit, but don’t think it will work with my fan. I’m going to have to duct the return air
through several dumps or I’ll be creating a bigger problem than I’m trying to solve.
Neil, the timer is a great idea. I can set it to come on before I arrive and shut down after quitin time,( when ever that is)
Grandpa, The inlet is 9 inches on the beast. Diameter is about 17in. so I’m working with the 20×20 filters for
capacity.
Thanks guys it’s been helpful.

-- Don, North Carolina,http://www.ncdon.com Working full time at retired.

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Grandpa

3256 posts in 2141 days


#8 posted 04-23-2011 02:16 AM

I think you are going in the right direction. I would be interested in some photos when you finish if you could do that. I just mentioned ACE because we have one nearby and Lowe’s is 45 miles on way. I go there when I can but I don’t go there often. I plan to use 3 fans in my shop. The timer is a must as I understand it. I don’t neet too much filtered air right now. I have 3 overhead doors. Those are on the north and south walls. Around here you just open the door and hope the table saw doesn’t blow away. The humidity is so low you can hardly stand it. Back when the great flood came and Noah built the Ark we only got .2” of rain that time. We are SSSSOOOO dry. wildfires all around.

View ncdon's profile

ncdon

214 posts in 2341 days


#9 posted 04-23-2011 11:30 AM

Grandpa, Okay I’ll be sure to post some results. I’ve got a lot of balls in the air right now. I’m insulating and hanging dry wall in the shop. Trying to get AC in there before the summer heat hits. This week I pulled a garage door out, studded the wall and hung some new steel siding. The wind and rain have not been my friend.
Cause I live in Murphy land the new siding doesn’t color match the old. (special order, nonreturnable, not all grays are created equal) Today weather permitting I paint the front of the shop. It never ends.

-- Don, North Carolina,http://www.ncdon.com Working full time at retired.

View Grandpa's profile

Grandpa

3256 posts in 2141 days


#10 posted 04-25-2011 05:07 AM

We finally got some of that moisture that falls from the sky too. What do they call that stuff??? Ah yes rain!!
Please do take some photos and give us the results of your project.

View patron's profile

patron

13538 posts in 2806 days


#11 posted 04-25-2011 05:27 AM

here is what i have found
and will get when i have things running better
they even make them custom

here is electrostatic air filters
hose wash
last a lifetime
1 to 3 micron filtering
buy once
last forever

http://www.air-filter-exchange.org/Maximum-Allergy-Relief-1-Electrostatic-Filters-Std-Sizes-Afe-1.aspx

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View ncdon's profile

ncdon

214 posts in 2341 days


#12 posted 04-26-2011 12:37 AM

Patron Thanks for the info. I like the idea of an aluminum frame better than the plastic one I picked up.

-- Don, North Carolina,http://www.ncdon.com Working full time at retired.

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