Pentz designed cyclone build update & filter question [Archive]

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Mike Weaver

07-18-2005, 3:20 PM

I bought one of the few pre-built Bill Pentz original cyclones a while back and have *just* gotten around to starting to assemble it.

I've hit the interior w/ rust converter once (it's mild steel, not galvanized) and will do so again before I spray it with primer & then truck bed liner for what I hope is a durable finish.

I managed to assemble the blower housing this past weekend (sorry, no pics...) and have it caulked up, ready to go.

I'll try to post some pics (gee, I guess I have to TAKE some pics first...) as I get farther along.

Now, to my question... In the book Workshop Dust Control, it mentions a cloth filter 10 to 1 max ratio for square footage of filter media to CFM.

But, obviously, depending on the type of dust, a lower ratio might be desirable.

If I were to get one of the 300 sq. ft. cartiridges from Wynn Environmental, that would equate to approzimately no more than a 5 to 1 ratio, assuming about 1500 CFM.

Do folks really use TWO of those cartridges on their cyclones?

Has anyone measured performance differences with one versus two?

On a related note, has anyone compared blowing the dust through the filter from the outside rather than from inside out to see if there's a difference in performance?

Yeah, two would be nice, but $$ is *always* a factor for me.

Thoughts?

Thanks in advance - this forum is GREAT!
-Mike
PS: Web addresses for reference:
http://billpentz.com//woodworking/cyclone/index.cfm
http://www.wynnenv.com/cartridge_filters.htm

Chris Padilla

07-18-2005, 3:27 PM

Mike,

http://www.sawmillcreek.org/showthread.php?t=9933

I have lottsa pics of the BP/CE design. In fact, I will probably resurrect that thread to add some more as I am now in the middle of hanging the DC...FINALLY!!! :) :)

Allan Johanson

07-18-2005, 4:44 PM

Hi Mike,

> Do folks really use TWO of those cartridges on their cyclones?

I did. Two Farr filters at just under 300 sq ft each.

> Has anyone measured performance differences with one versus two?

Yup. I measured the Farr filters when they are clean. I was able to put almost 1000 cfm into one filter before it showed any sign of impeding airflow. Dumping 1500cfm into one filter only resulted in a loss of 15 cfm when compared to no filter at all. When the filters are dirty, this will of course change.

>On a related note, has anyone compared blowing the dust through the filter from the outside rather than from inside out to see if there's a difference in performance?

I didn't bother with a performance difference test, but the test above was done by stuffing the 8" cyclone outlet directly into the top of a filter and taping up the small gap.

But....Farr says to use these filters "outside-in" which is opposite from my test and what you see from Oneida/Grizz/Bill Pentz, etc. The rationale is because the pleats are much closer together on the inside of the filter compared to the outside. So, given the same amount of dust hitting the filter, it can have a more negative impact on performance if you send the dust to the inside vs the outside (easier to clog with the narrow pleats).

However, some filters people use are "wide pleat" filters and this may not matter much. Also, the vast majority of us are hobbyists and we aren't creating that much sawdust so if you have to clean the filters more often one way vs another, it may not matter much at all.

>Yeah, two would be nice, but $$ is *always* a factor for me.

I hear ya. You can always run one for a while and see how it goes. If you find you need to clean it more often than you'd like, buy a second one.

>Thoughts?

I'm a loon. I'll admit it and here's some proof. I built a large filter box (smaller than I'd have liked due to a lack of space) and this filter box has 2 stages to it. The pre-filter stage to catch larger particles and the fine particulate stage that hold the two Farr filters. I know I'm going to let the dust bin overflow and at that point my cyclone will pack the expensive Farr filters full of sawdust. I don't want to spend the time cleaning them. So if I let the dust bin overflow then the dust will get trapped in the first stage. It has a basic electrostatic hammock furnace filter to act as a prefilter.

I've also hooked up two Magnehelic gauges to monitor the pressure in each chamber so I can tell when I need to clean the filters. Running two gauges like I am can get confusing because a dirty filter in one chamber can falsely affect the readings in the other, but I know how to deal with that.

I'm having fun. :D

Here are three pics for you.

1) Pic of the Farr filter in an attempt to show you how much closer the pleats are on the inside vs the outside

2) Pic of the filter box all sealed up.

3) Pic of the filter box so you can see the two Farr filters and the prefilter.

Cheers,

Allan

Tony Shaftel

07-18-2005, 5:39 PM

I also use two Farrs. I had one with my old DC system, got another as I was building a new one, then saw no reason why not to use both. I have them side by side in a cabinet blowing outside-in. Once in a great awhile I take them out and run the shop vac along each cleat. A bit tedious but it cleans them off pretty well.

Mike Weaver

07-19-2005, 5:04 AM

Thanks guys!

Allan, you've created another set of questions that I'd like to ask.

Is the "panel" in that box made from a pair of those furnace filters? It's tough to see on my laptop monitor. ;-)

For the blower outlet - I recall you posted a bit back that you gained something like 80cfm by using an 8" outlet. Did you modify the plans from Bill, or just transition his "normal" blower to an 8" round?

Did you get your filters from Wynn Environmental? (I don't see a Farr style non-lined 300 sq. ft. filter on their page...I'll have to call them).

I think that even though cost is a factor, getting two is the right thing to do. I could always add one later, but I know me. I'll never get around to it!

Thanks again - you folks show me every time I post hos great this forum is!!

-Mike
PS Thanks again to Bill Pentz! I won't say he's saved my marriage, but it hasn't hurt any... <img>

Matt Meiser

07-19-2005, 7:30 AM

Allan Johanson

07-19-2005, 1:23 PM

Hey guys,

>Is the "panel" in that box made from a pair of those furnace filters? It's tough to see on my laptop monitor. ;-)

:) Actually, it's made from half of a filter. The filters I have are 60"x30" electrostatic hammock furnace filters and I'm using a 60"x15" strip for this. Yes, it's cut into two pieces because it was a tiny bit short to span the entire vertical distance. It's simply stapled to the wooden frame. I might change this mounting method to be like screen door construction with the rubber caulking strip you push into a groove.

This panel just slides into dados on the top and bottom of the cabinet for easy servicing or removal if it turns out to annoy me too much.

BUT, if I had the space I'd make this prefilter be much larger. With the small surface area it might be prone to getting caked and lowering performance. I need to run it longer and really put it to the test.

>For the blower outlet - I recall you posted a bit back that you gained something like 80cfm by using an 8" outlet. Did you modify the plans from Bill, or just transition his "normal" blower to an 8" round?

#2 :) Some quick math showed me that the rectangular blower outlet was slightly larger than an 8" snaplock pipe. I made a wooden adapter plate to mount the snaplock pipe to and this plate screws to the blower housing. A little sealant and a small piece of metal foil tape to cover the tiny triangle-shaped gap at the top of the pipe and it's done. I used regular 28g 8" snaplock from the Borg for this. I've included a pic for you.

>Did you get your filters from Wynn Environmental? (I don't see a Farr style non-lined 300 sq. ft. filter on their page...I'll have to call them).

I bought my filters direct from Farr. They have a distribution outlet about 40 mins from me.

>I think that even though cost is a factor, getting two is the right thing to do. I could always add one later, but I know me. I'll never get around to it!

You'd get around to it if you had to clean it frequently. :p The thing is I don't know what your filter cleaning frequency is going to be. Maybe you'd be fine with one??? It's your call.

Cheers,

Allan

Allan Johanson

07-19-2005, 1:35 PM

Allan, that's a great idea. After overfilling my bin twice in recent months, that's something I need to consider. I'm also planning to change to blowing outside-in, but haven't done it yet as I'll have to buy new filters to do so.

Thanks. I heard some stories about clogged filters that wouldn't clean easily and negatively affected performance so I decided to try something to help save my bacon - at least until I develop a reliable dust bin level detector. I'll figure something out.

If you try the pre-filter thing, try and make it have as much surface area as possible. Or maybe buy PSI's dust bin level detector and have it turn on a flashing red light or something. I'm not sure how well it works though.

I'll keep you guys posted on any issues with the prefilter as I come across them. Consider this an "experiment in progress". :D

Cheers,

Allan

Mike Weaver

07-20-2005, 7:39 AM

<snip>

BUT, if I had the space I'd make this prefilter be much larger. With the small surface area it might be prone to getting caked and lowering performance. I need to run it longer and really put it to the test.

<snip>
#2 :) Some quick math showed me that the rectangular blower outlet was slightly larger than an 8" snaplock pipe. I made a wooden adapter plate to mount the snaplock pipe to and this plate screws to the blower housing. A little sealant and a small piece of metal foil tape to cover the tiny triangle-shaped gap at the top of the pipe and it's done. I used regular 28g 8" snaplock from the Borg for this. I've included a pic for you.

<snip>
Allan

Allan,

One thought regarding the size of the pre-filter... From your setup, you *might* be able to basically make a "thick door" that's say, 3" deep, with a prefilter over the Farr filters? (basically, turn the door into a 3" deep box so that the air can get around the corner to the Farr filters from the front & put another prefilter on the front face?).

Anyway, if I recall correctly, you were getting some excellent performance numbers so I'm not sure I'd worry about that existing prefilter setup causing any issues...

Thanks for the closeup of the outlet transition! Another excellent idea!

Cheers,
-Mike</snip></snip></snip>

Mike Weaver

07-21-2005, 7:20 AM

Folks,
I had a very nice conversation with Rick at Wynn yesterday afternoon.
We batted around various filter options, and I was impressed with both his knowledge and willingness to share it.

We talked about various filter materials, inside out vs. outside in flow, filter surface area, etc.

In the end, I bought a pair of the 300 sq. ft. Farr compatible filters (9L300BL) filters and look forward to installing them soon.

Thanks for the push to get a pair of filters.

On the cyclone front, I managed to get the primer on the inside done after mowing the back yard.

Cheers,
-Mike

Chris Padilla

07-21-2005, 12:57 PM

Mike,

You say they are "Farr compatible"; does this mean they aren't the Farr brand? Just curious. I need to pick up a pair of filters myself. Do you plan to do them outside-in? That sounds like a good idea.

Do you have Rick's contact info? I might like to pick his brain as well.

I just started hanging my cyclone and I am not happy with the way it turned out so I am going to redo it I think. I hate to but I think I'll sleep better at night if I do it more "correctly" than I've done it.

Allan Johanson

07-21-2005, 2:37 PM

Mike & Chris:

FYI, Farr makes a few different types of cartridge filters. The one I'm using is for their Tenkay dust collector and I believe the part # is 125154-5. This may explain any hesitation or confusion if you talk to a vendor and they want to know "which kind".

Mike: Thanks. The idea of yours to make a "thick door" is similar to one I've thought of as well. Everything is on hold until my lathe arrives though since it'll be a super tight fit to get my dust bin out. When I get that spacing figured out that I'll know if I can mess around with the filter box some more.

What were Rick's views on filtering outside-in vs inside-out? Just curious. I'm going to stick with Farr's method in any case.

Chris: What don't you like about your cyclone? IIRC it seemed to go fairly well except for the rectangular to 6" round transition. If you try the method I used (as posted in the link you provided above) then you might find it'll go a lot easier.

Also, if you want to see my system in person when you are coming to Vancouver in Sept, drop me a line. I'm just inside Canada, 10 mins from the US/CDN border as you come up I5 from Seattle. I also appreciate German machinery like you do. You won't find a BMW in my garage though, but you'll find something that'll give an M5 a run for its money. ;)

Cheers,

Allan

Mike Weaver

07-21-2005, 3:50 PM

Guys,

Chris: Rick is with Wynn Environmentals and the cartridges they have are at: http://www.wynnenv.com/cartridge_filters.htm

The filters I bought are the 9L300BL which are Farr compatible, open ended 300 sq. ft. Blended filters. They are NOT made by Farr, but are similar. More on that in a minute...

Allan: Rick & I talked at length about that. Basically, unless you fully clog the filter, there's no difference. Theoretically, with a fully loaded filter, there's a "savings" in pressure loss. I think he calculated a 44% difference in static pressure created by running inside-out versus outside-in.

He made good sense and i think I've abandoned doing them like you (outside-in).

Now as to the Farr versus Wynn made... According to Rick, Farr makes what they call a 0.2 micron filter that's 99.995% efficient at 0.5 micron. They can claim a 0.2 micron filter because they actually rate the efficiency using particles of something like 0.2 to 1.0 micron. It's a nice filter to be sure, but a bit misleading if Rick is correct.

He also relayed that it's not possible for us, as woodworkers, to generate a 0.5 micron particle in the first place.

As for filter media, the Blend they sell is 80/20 (cellulose/polyester) and should last 5-10 years, maybe more. Humidity should be no cause for concern & with the poly, it shouldn't get brittle.

The filters I bought have a screen inside & out because they can't make a 300 sq. ft. filter in the blend w/out the extra screen for support.

They do sell the genuine Farr filters and replacements for the external Oneida filters to boot in the spun poly.

As I said yesterday, Rick was more than willing to discuss all this with me.

Oh, and the filters are $63 each.... a LOT less than the Farr filters. (Allan, please don't take that as a knock of the genuine filters you have - it's not meant to be in the least, ok?)

Well, enough for now...I'm off to a Cub Scout Day Camp picnic...<img>

Cheers, and again - thanks for the great suggestions!
-Mike
PS I promise to at least post pics when I'm done if I can't get some up before then.

Allan Johanson

07-21-2005, 4:15 PM

Hi Mike,

Thanks a bunch for the info. I appreciate it. No worries re: "knocking" the Farr filters. I have the utmost respect for the Wynn filters. I went with Farr because I live in Canada, about 40 mins from a Camfil-Farr depot (a few blocks from Lee Valley and KMS Tools as well :cool: ) and was able to buy these filters for $80 CDN each ($66 US). No shipping fees or border hassles with customs trying to import filters. When I contacted Farr about the filtering efficiency, they notified me in writing that they are 99.99% efficient on 0.5 micron particles for most applications. No mention of 0.2 micron particles. Well, not officially. ;)

Interesting viewpoint Rick has with the thinking we can't generate particles smaller than 0.5 microns in our shops. Believe me - I sure hope he's right!

I think you're in great hands with the Wynn filters. If I were you I'd buy them with no regrets. None at all.

Cheers,

Allan

P.S. You're not going to let your dust bin overflow, are you? ;) Check out the PSI system and see if folks like it. It might save your bacon.

Don Baer

07-21-2005, 4:57 PM

Just a note on particle size. There are at present 2 standards set by OSHA. The first is called PM 10 which is anything 10 microns or smaller and the second is PM 2.5 which is 2.5 micron or smaller. The reason for these two sizes is that anything bigger then PM 10 will be filtered out by your respitory system before it enters the lungs and is trapped there. (Asbestos dusts is between 6 and 8 microns). Particles 1 micron and smaller not only enter the lungs but are so small that they can be absorbed directly into your blood so there is talk about a third standard which will obviosly be called PM 1. I personaly would still wear a resperator especialy when sanding.

Chris Padilla

07-21-2005, 5:07 PM

Chris: What don't you like about your cyclone? IIRC it seemed to go fairly well except for the rectangular to 6" round transition. If you try the method I used (as posted in the link you provided above) then you might find it'll go a lot easier.

Also, if you want to see my system in person when you are coming to Vancouver in Sept, drop me a line. I'm just inside Canada, 10 mins from the US/CDN border as you come up I5 from Seattle. I also appreciate German machinery like you do. You won't find a BMW in my garage though, but you'll find something that'll give an M5 a run for its money. ;)

Cheers,

Allan

Allan,

I'm in the impeller housing hanging phase. I haven't yet connected the barrel/cone to my impeller housing. I'm putting the cylcone in a portion of my garage that has a vaulted ceiling with about a 15 degree slope to it so I spent some time rigging up a nice level platform from which to hang the impeller housing. After finally getting it up there, I am finding it is too close to the two walls and I decided that my method of fastening it to the rafter wasn't as good as it could be so I'm going to redo it...that is all.

Thanks for the invite...might be able to muster it. Hmm, no BMW but still made in Germany? That calls for either Porsche, Mercedes, or Audi!

Mike Weaver

07-21-2005, 7:03 PM