Going to use HEPA filters

A

amtaustin

New member
I have not installed my system yet (just ordered the parts), but I have decided to use true HEPA filters with my system. Since my workshop is a hobby shop, it made more sense to me to get a filter system which does not need "seasoning" to get to target filter particle efficiency. Plus, with a cyclone, it could take a very long time to get a filter like that seasoned.

I ordered 2 GE HEPA certified filters that are 18" diameter an 20" tall, and I will stack these. These have large pleats and are washable, so hopefully cleaning is easy. Each filter is 75 ft^2, so 150 ft^2 total.

If there is too much static pressure, I will probably get a 3rd filter and add to the stack. This filter has been tested at 500 CFM with a static pressure of 0.86", so 1000 CFM (my target flow rate) with two of them should still be 0.86". I'll have to see how they perform once they get a little dirty.

Anyone else try a HEPA filter on their cyclone?
 
I have not used these filters but just base on your numbers I would order that third filter as the clearvue moves a shocking amount of air.
 
If you are buying a ClearVue Cyclone, why not use the Wynn Nano filters that are best suited for the high airflow that this unit offers? They are 99.999% efficient on 0.5 micron particulates and larger and have hundreds of square feet of surface area.
 
Like I stated in my original post, I do not want to wait until the nano filters actually filter at that level. They clearly do -not- filter 99.999 @0.5 micron out of the box: http://www.oneida-air.com/pdf/blue-heaven-filtration-test-result-13-2032A.pdf In fact they only filter 82% of the dust in that size!

Even after loading the filter with cake, the filter efficiency did not reach 99.999% for 0.5 micron. And the SP went to 4", so I don't see how they will offer better airflow at their peak filter efficiency. http://www.oneida-air.com/pdf/blue-heaven-filtration-test-result-14-021.pdf

And after cleaning the filters, the filter efficiency was once again very low, close to the levels of a new filter: http://www.oneida-air.com/pdf/blue-heaven-filtration-test-result-14-021A.pdf

These tests were conducted by an independent lab and not the company selling these filters.

My take on this is: if I am going to invest this amount of money to protect my health, why would I not finish the job and use the filter with the best and most consistent filter efficiency? Even if I have to buy a third filter, still seems like money well spent.
 
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In my opinion, the posts above miss two of the key reasons that filters like the Wynn Nano filters are coupled to ClearVue Cyclones. First, the ClearVue has very efficient dust removal efficiency before the air ever gets to the filters downstream of the blower. As we all know, it is the finest dust particles that stay entrained in the exhaust air. Less efficient cyclones or conventional dust collectors (like the HF 2HP unit or many of the cyclones on the market), remove substantially less dust from the initial input air stream due to inadequacies in their designs.

Second, less effective filter media found in most fabric filters ("bags") and in many canister filters do increase slightly in capture efficiency after they get a "dust cake", but at the expense of reduced air flow as the dust cake develops. Wynn Nano filters are design to remove 99.999% of 0.5 micron and larger particles when clean and because of their high square footage, pass the blower output air through the filters without much static pressure loss. The rated efficiency of these filters is not after they develop any "dust cake", but it is a measure of how they perform when clean. As said by SawSucker, dust collectors are not air filtration units, but ClearVue Cyclones are very efficient at removing the vast majority of particulates from that generated by woodworking tools (there are numerous posts here and other forums where Dylos measurements would show that a running CV1800 does effectively clean particulates from shop air).

I remember my first visit to ClearVue back in 2007 when the company was owned by Ed and Matt Morgano just east of Pickens, SC (about 30 miles from where I live in western NC). They had a CV Max operating in their production shop attached to two CNC machines making Blower housings, filter transitions and the base and supports for the original Mini-CV06, all from MDF. They ran the CNC's every day and generated lots of dust. The bin beneath the cyclone was changed every few days, but Matt reported they emptied the filter cleanout box about "once every few months". A few taps on the metal flanges dislodges any modest build up on the filter media. My experience mirrors Matt's statement even though I do not run MDF through a CNC machine.

The bottom line? A highly efficient cyclone equipped with a set of high efficiency filters works very well for the removal of the vast majority of dust captured from woodworking machines. If you don't select the best products as are married together by ClearVue, than you might encounter a less safe working environment. That said, I still wear a dust mask when operating my Festool ROS, even when it is connected to a high efficiency dust extractor (a CT36 with HEPA filtration).

And to set the record straight, I do not work for ClearVue Cyclones, but I do have an agreement with them for the bin sensor accessory that I manufacture. I have owned a CV1800 since 2007.
 
McRabbet said:
Wynn Nano filters[/URL] are design to remove 99.999% of 0.5 micron and larger particles when clean
Click to expand...

Not true: http://www.oneida-air.com/pdf/blue-heaven-filtration-test-result-13-2032A.pdf

Even Wynn states the same thing regarding the nano filters:
http://wynnenv.com/filter-efficiency/

Both sources have different graphs/values, but similar results. The real kicker, is that to get top efficiency, the static pressure goes to ~4"!!!

You make a good point about very little of the dust getting to the filters in the first place, but that just works against the nano filter's efficiency, since they do need dust cake to have high filter efficiency. I wonder how long it takes to get enough filter cake on them to get the filter efficiency near the hepa filters, which do it out of the box.
 
Many years ago I had a ShopSmith dust collector. When I was visiting a woodworking trade show, I visited a booth that made custom singed felt dust bags for industrial applications. They were from Florida and were very helpful. I asked what I could do to get more efficiency out of my ShopSmith DC. Their advice was to get an exhaust bag that was the largest bag I could fit into my shop. They pointed across the convention center and pointed out that all the dust bags that were taught and ballooning out under the air pressure were too small.

So, I ordered a custom exhaust bag from them that was so tall that it touched the ten foot high trusses in my shop and the bag was suspended by a cross shaped PVC pipe that was slipped thru loops sewn in the top of the bag.

But what I remember most about the custom bag were the instructions. to whit: buy a 5 pound bag of flour and let the DC suck it in thru a blast gate. Literally, the "cake" was made by cake flour and it was charged instantaneously.

So for what it is worth - be pragmatic. Get yourself 5 or 10 pounds of flour and charge your filters.
 
True HEPA??

True HEPA??

If you study up on HEPA, it is not only designed to separate to .3 micron, but to retain anything trapped. That throws the idea of cleaning the element right out the window. HEPA is for capturing radioactive and biological contaminants so they can be properly disposed off.
Something to think about.
Don
 
HEPA filters are not my issue. I wouldn't waste my money, for the very reasons Don points out. HEPA filters are designed to be used and sent to the trash. I was only referring to the issue of filters in general and a method of giving them a pre-cake treatment.
 
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