Air Filter

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Review by David Murray posted 02-14-2010 06:23 PM 6698 views 1 time favorited 7 comments Add to Favorites Watch
Air Filter Air Filter Air Filter Click the pictures to enlarge them

I finally took the plunge and bought an air filter unit for my shop. It was a purchase that I didn’t put on a very high priority. My thinking was “It really isn’t really a tool”, after all you can’t cut, shape, grind, drill or sand with it. After all I have a dust collector what more do I need. I always figured the fine dust that was always collecting on everything was okay, after this is a woodworking shop. Then I read a few articles on the long term health hazards of fine dust to the lungs, so I thought maybe its time to make the investment.

After doing research on several different units I went with this Grizzly model for several reasons. Due to the size of my shop(30’x35’) I wanted a fairly high CFM. After using this formula to figure out how many times it would recirculate the air in my shop per hour.

Step 1. Calculate, how long it takes to circulate all
the volume of air in a room with the double air filter;
where W = Width, L = Length and H = Height
of your room, in feet. The rate of air movement for
the air filter is 1400 cubic feet per minute.

W’ x L’ x H’ then divide that number by CFM rating. for my shop it worked out to 7.5 mins.

Step 2. Calculate how many times per hour the
volume is recirculated through the double air filter
by dividing 60 minutes by the amount of time it
takes to circulate the volume once. The result is
listed as times per hour.

For my shop it was 7.5 times per hour. Compares to 5.7 times per hour for a 1000 CFM unit.

I hope I didn’t confuse anyone other than myself. Now to the unit I bought.

It has 2 filters a primary one that is a standard 16” x 20” filter (a furnace filter would work), the one that came with the unit is 30 micron and washable, it has a carboard frame so I’m not sure how well it will hold up. The secondary filter is 2 micron and is also washable and is much more sturdy being made of plastic.

It has 5 fan speeds (800-1400 CFM) and a timer for 2 – 8 hours in 2 hr increments, also can run continious. these features are controlled with a remote control. Uses a standard 110V outlet.

Seems to be fairly quite and does a pretty good job in my shop. I usually set it to run for 2 hours after I leave and I am happy with its performance. It has cut way down on the dust that settles at the end of the day, and has been a welcome addition to my shop and would recommend one. I wish I had not waited so long to make this purchase. Reguardless of what manfacture you may choose it is worth the investment. Hopefully this review is a help to my fellow LJ’s.

-- Dave from "The Sawdust Shed"

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David Murray

187 posts in 3915 days

7 comments so far

View a1Jim's profile


118079 posts in 4378 days

#1 posted 02-14-2010 06:50 PM

View John Gray's profile

John Gray

2370 posts in 4686 days

#2 posted 02-14-2010 07:02 PM

I have had one of these units for almost 3 years now and it works great.
1st thing I learned is DO NOT run it when you are spray painting, the spray clogs up the outside, primary, filter very quickly.
2nd thing I learned the filter units for it is expensive when you figure in shipping.
3rd thing I learned is if you take care of the outside filter, the primary one, the one on the inside stays pretty good looking for “a long time”.
Also, now that I have a Delta 50-760 filter,, I don’t use the overhead one near as often.

-- Only the Shadow knows....................

View asmitty's profile


39 posts in 3836 days

#3 posted 02-16-2010 02:47 AM

thanks for the review…this gives some nice insight to this tool. I always enjoy reading reviews from the end consumer of woodworking tools. enjoy your new tool and cleaner shop!

-- even a mosquito doesn't get a slap on the back until he starts to work...

View WoodArtbyJR's profile


428 posts in 3766 days

#4 posted 03-19-2011 06:36 PM

I know this thread is over a year old but just wanted to share. Based on the reviews of the air filtration units (Grizzly, Jet, HF, Delts, JDS & home made) I purchased the Grizzly G9956 unit March ‘11. Some the main reasons were, 1. the 5 micron filter size (16”x20” easy replacement) as many of the others were odd sized and you had to go thru the OEM to get a replacement, 2. CFM of the blower, 3. price. This unit was well packaged for shipment. Easy to hang from the ceiling and the remote IS NOT DIRECT SIGHT. I can turn it on or off from anywhere in the shop. As noted by one of the other reviewers, the smell in the shop is much cleaner. I give this a two thumbs up.

-- Jim Roberts, Port Orchard Washington

View marvinlee's profile


37 posts in 2990 days

#5 posted 07-01-2012 01:18 AM

Based on the three reviews, I ordered the Grizzly G9956. Thanks.

-- Marvin, Kiger Island

View WoodNDust's profile


228 posts in 2907 days

#6 posted 09-25-2012 03:04 AM

Based on these reviews, I ordered the Grizzly G9956, too. Thanks.

David – thanks for the pictures and great info!!

View stefang's profile


17039 posts in 4135 days

#7 posted 11-25-2014 02:20 PM

Thanks for this review and especially the calculations. I just bought a new Record air filter and it will be interesting to see how the calcs apply to it in my small shop.

-- Mike, an American living in Norway.

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