DC filter

[brent]

I nee to upgrade the filter on my HF DC. I know they is a Wynn filter that is easy to retro onto the unit, but I have torn mine apart and put the motor and impeller on top of a drum.
So, I am looking for a cheap way to put a decent filter onto the output of the cyclone. The size does not matter anymore. I plan to cap one end for the input and then cap the other with a hole in it and either attach a small bucket to it, or run a hose down to something that would catch anything making it through to the filter.
I saw these on eBay. The price is certainly right, but I am not sure of how small it will capture. It says it has 105ft^2 of media and i THINK that is enough for a HF.
cgi.ebay.com/New-26-Donaldson-Torit-Dust-Collector-Filter-P191672_W0QQitemZ250447201338QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3a4fd1043a#ht_1593wt_941
Any thoughts on this, guys?

[TDHofstetter]

It's hard to know much about the filtration granularity or the airflow obstruction. Donaldson's eCatalog ain't very informative...

[brent]

Yea, I looked around on a lot of sites and could not find any specs on it either. I may have to go with a wynn. I would rather not, because of the cost difference, but I don't want to waste money if it is not going to get the fine stuff.
I have a downdraft table built into my table saw outfeed, and it is ready to go except for drilling the holes. I have not bothered because right now there is not point in a dd table. It would just suck the fine stuff up and then shoot it back in the air through the bags.

[TDHofstetter]

You might be surprised - those stock bags catch a LOT of stuff, especially when they've got a coating of dust on the inside. Makes the bags finer. They won't catch it ALL, but they'll get a dang lot of it. Go ahead & make that dd table work...

[Ruffnek]

Brent, I went to the Donaldson-Torit site and found that the cartridge you showed is an Ultra-Bond, nanofiber, MERV 13 filter (checked the serial number)

The site had this to say about those filters..."Compared to other typical cellulose or 80/20 blend filters, standard Ultra-Web rated MERV 13 provides 40% lower emissions on 1 micron dust and 58% lower emissions on 0.5 micron particles. "

From that statement, I'd say the filter is probably a 0.5 - 2.0 micron filter. That's about as good as it gets. For the $40 price they showed, I think I'd get it.

[TDHofstetter]

Now... will a filter that small handle that much airflow?

[Beamer]

Depends wholely on the surface area, I think.

The wynn I have is much bigger in diameter. I have 100-something square feet of filter surface area and is 99.999% efficient at 1 micron and above.

[Ruffnek]

Nov 8, 2009 20:01:36 GMT -6 TDHofstetter said:

Now... will a filter that small handle that much airflow?

Generally speaking, the smaller the openings, the more air flow it will handle because there is a lot more open space per given area. It sounds opposite to what it should be but that's the facts. The larger the openings, the larger the blank space between the openings.

On a bag filter with large openings...say 10-20 microns, the bag will be inflated fully and feel hard to the touch when the DC is running.

Replace that bag with a 1-2 micron filter bag and it will barely be inflated with the DC running because there are infinitely m ore openings for the air to pass through.

Edit In: As a comparison, the 13" x 39" pleated, spun poly cartridge on my cyclone filters from 0.5 - 2.0 microns and it will easily pass 1500 cfm of air.

[TDHofstetter]

I'll grant you that, on one condition - that the fibers that make up the filter medium are also far smaller. If they're not... then the reverse is true.

Picture a window opening in a wall. Nail one plank across that opening - that's a coarse filter. Nail two more planks the same size across the opening - that's a finer filter, but will pass less air. BUT if the planks are all 1/4 as wide, it's still a finer filter but will pass more air.

[brent]

Thanks for all the info. I am thinking about going ahead and trying it.