Hmm, wondering if anybody at ClearView, Wood mag, Oneida, Grizzly, Penn State Industries, etc are reading this or are we just spitting into the wind? Excellent thread though. Nice to have some expertise on board.
Hmm, wondering if anybody at ClearView, Wood mag, Oneida, Grizzly, Penn State Industries, etc are reading this or are we just spitting into the wind? Excellent thread though. Nice to have some expertise on board.
Contributor
I know that it WAS dicussed over AT wood's little furom site. Mod over there basically shut all discussion down, saying "it is set in stone, can't change anything"
Typical WOOD operation....
Member
I agree with you completely in that bad choices do not cancel out one another. My statement is in the spirit of "penny wise and pound foolish". There has been some level of "testing" done with dylos meters that demonstrates a non-Bill-Pentz-Style-perfect-setup can still result in good air quality.Originally Posted by Greg Portland
Is a 2HP machine with a Thien baffle, and a Wynn filter along with a decent Jet Air cleaner as good as a 5HP clear vue? Probably not, but it gets you a large percentage of the way there. And based on what Phil (and others) have found in their testing is that a "mediocre" setup will result in pretty darn good air quality.
I wonder what models of SawStops all the die-hard dust collectors folks have? I assume they all have SawStops as why would you risk the health of your fingers by having a table saw that does not have flesh detecting technology?
- Lou
Contributor
Lou, you bring up a good point. While health concerns play some part, it is my interest in experimenting and trying to improve the DC that probably drives my train. Although I always replace my Suburban brakes with aftermarket upgrades as I think the stock ones are crappy, I can't bring myself to get excited about giving up my old saws for a SS. Not exactly logical. Dave
Member
>>>> i would like to see all the players take to the field
May be old news but:
There is already some grousing going on at the Wood Magazine web site. For example, ClearVue is not included in the test as their price exceeded Wood's price point for inclusion.
You can go to the Wood web site and see the discussion. I thought it interesting that one person called ClearVue to ask whether they were included in the testing. ClearVue responded that they were not even aware that dust collectors were being tested. Wood "blind buys" the tools that the test just as does Consumer Reports.
Last edited by Howard Acheson; 01-26-2013 at 10:36 AM.
Howie.........
Member
Here is some info that addresses this question. It includes data and comments I collected for an article I wrote for a woodworking club newsletter a number of years ago.
DO NOT RELY ON AN AIR CLEANER TO ACT AS A DUST COLLECTOR. The purpose of an air cleaner is to keep airborne dust in suspension and reduce airborne dust as quickly as possible AFTER THE DUST PRODUCER HAS BEEN TURNED OFF.
Finally, if you are looking for health benefits, you will not find any air cleaner manufacturer that makes health claims because there are few health benefits. CATCHING DUST AT IT'S SOURCE IS THE BEST LONG TERM GOAL. Rick Peters', author of "Controlling Dust in the Workshop", makes the point that spending your money getting the dust at its source is a better investment than trying to capture it after it is already airborne. If the dust is in the air, it's going to be in your nose and lungs too. Robert Witter of Oneida Air Systems has noted that "overhead cleaners can only lower ambient dust levels AFTER THE SOURCE OF EMISSIONS IS SHUT DOWN, and they take several hours to do this. This is why they are not used in industry." The absolute best answer, if health is the primary concern, is to use a NIOSH approved respirator. The dust cleaner will help keep your shop cleaner but have minimal or no health benefits. OSHA takes this position too. They measure the number of particles per a volume and most air cleaners will not satisfy their specs.
By Robert Witter, Oneida Air Systems, Chief Engineer
"Air quality tests show that Source collection (dust collection) can lower the dust loading in a wood shop by a factor of 5 to 20 times over a shop with no or bad dust collection. The goal is to lower the dust level below 5 milligrams per cubic meter(OSHA reg). A good DC system can keep the dust loading down to 1-2 mgM3. This means you inhale the quantity of dust in ten years that might have inhaled in 1 year. A little dust is OK. Overhead cleaners can only lower ambient dust levels after the source of emission is shut down, and they take several hours to do this. This is why they are not used in industry.Cloth filters can accomplish 99.9 % sub-micron filtration. For example, carbon black can be filtered with cloth but at a 2:1 air to cloth ratio. That's allot of filter bags. Good Felt filters 16oz will filter 99.5% of material between 0.2-2.0 micron at 10:1 air to cloth ratio. Cartridges pleat more cloth area into a smaller space, that's all. In the air sample tests i have seen only a negligible % of wood flour is as small as 1-2 microns, so a filter efficiency of 99% @ 1-2 microns is more than sufficient, and ostensibly represents 100% filtration for wood dust."
Howie.........
Member
>>>> Mod over there basically shut all discussion down, saying "it is set in stone, can't change anything"
I don't see that the discussion has been shut down. It's a fact that testing has been completed and Wood apparently does not intend to open the testing. That's just a fact. But, the thread is still open and you can continue to make submission. The thread is not closed down.
Howie.........
[OP]
Contributor
I surmise that no one at Wood Magazine is reading this; neither the editors or the moderators. Their forum is "prompted" daily by their moderators and there are a number of "honored" "advisors", forum members, if you will, who consistently take the position of the moderators and magazine. Because of this the whole forum seems to have a narrow, closed minded viewpoint on many topics. Any criticism of the magazine is quickly shut down
Sometimes we at the Creek go overboard in detail and debate, BUT, when a topic is raised Everything is fair game, and I for one appreciate it. Thanks fellas
Member
Not sure "everything is fair game" is a true statement. It sure wasn't a few years ago! There was big SMC thread (battle royale) involving among other participants, big names in dust collection like Bill Pentz, Robert Witter (Oneida), Shiraz Balolia (CEO Grizzly), Rick Wynn (Wynn Environmental), and others, about filter specs, claims, and testing. There were even a few obvious shills* who joined SMC to participate in that thread specifically to attack* Bill Pentz. * (Joined SMC during the thread, no prior posting, none afterward, no facts, just attack rhetoric in their posts. When they registered they listed their occupation as in the "air quality business" or something similar, but erred by listing their home towns - same as or near Oneida!!) Anyway, Bill Pentz was subsequently banned, etc. and a year or two later the thread was sanitized or deleted. I used to have a link, but the last time I checked it was gone or edited beyond recognition and their was no evidence of the shills in the member's list.
Guest
The purpose of an air cleaner is to get whatever the primary DC missed. It is not intended to keep anything in suspension, it uses a blower to move air through a permeable filter. A side-effect of using the blower would be currents that may keep dust suspended.
But it is designed to get what the primary system missed.
If we didn't learn anything else from the Dylos group buys, at least we did learn that none of us have DC's capable of always catching all the fines at all the tools.
Catching everything at every tool just isn't realistic.
Anyone with a Dylos meter can tell you that when the air cleaner is running, it is reducing counts. Maybe another tool is increasing counts, but the air scrubber is likewise reducing them.
Many of our shops aren't that large, and the air cleaners can often exchange the air multiple times every hour (as many as six to ten times).
And air cleaners ARE used in industry. Just google "industrial air cleaner" and you'll find quite a few manufacturers that make enormous ones. And even the larger Jet and Grizzly units that move up to 2000-CFM are pretty much units designed for light manufacturing. You just aren't going to run into those in many hobby shops.
The thing to keep in mind, though, is that air cleaners have been shown by our hobbyist friends to keep counts down in their shops. Even when they make every effort to collect everything they can at the tool, running the air cleaner provides a helpful 2nd line of defense. We have to stop discouraging people from using them, IMHO.
Howard,
Where did you get the quotes from Oneida? I can't get them to answer a simple email asking what size impeller I have.
Member
This is true, BUT...it comes at a price. The less filter area you have, the higher the filter face velocity (A/C ratio) and the deeper particles will get trapped inside the filter making it harder to clean. This also caused the filter pressure drop to build much quicker requiring more frequent cleanings. As the pressure drop across the filter builds, the CFM at the hood is reduced because more resistance is added to the fan. The filter is still meeting this efficiency (maybe even better), but you have a lower exhaust volume at the hood which allows more particles to escape the collection system at the source of generation.
Large particles are easier to clean from the filter media, so adding a "high efficiency" cyclone in front of the media can magnify the problem because only smalll particulate is getting through. Small particles get embedded in the media and are not able to be removed without damaging the filter. So the small particles stay in the media and accumulate between cleanings. This leads to the filter blinding, meaning that the clean pressure drop has approached the dirty pressure drop and has restricted airflow. (Don't necessarily think of your filters as a one-time buy.)
Cartridges or pleated filters afford more area in the same real estate, BUT...they also typically require a lower face velocity for the same application as a bag filter (resulting in more filter area required). Pleated media is more difficult to clean because of the pleats. The lower filter face velocity helps prevent the small particles from embedding too deep in the media.
Mike
Last edited by Michael W. Clark; 01-26-2013 at 2:02 PM.
Contributor
Michael, those are important points and they don't get discussed a lot. Would you differentiate between cloth and cartridges somewhat? Are chips in the filter beneficial for bags due to their cleaning ability or are you talking about larger sized dust vs the small stuff when you talk about letting it into the filters? Is a high efficiency cyclone a benefit with certain types of filters or not?
I like the space savings of cartridges and have been very happy with my Wynn Nano- I run four- but my old cloth bags gave me very low Dylos numbers too. Not quite as good as the Nano but easier to clean. As the system got more powerful it wasn't practical to keep adding bags but I liked them. There is also the issue of tight vs loose pleats. I've found that if I screw up and pull some chips in the Nano the pleats are so tight that they don't stick as much as they did on my spun bond wide pleat filter. Can't say if the fine dust cleans as easily though.
Any thoughts? Dave
Member
David,
I'm not sure about your questions on those specific types of media your referenced. Most media can be made in a bag or pleated form. Although, some thicker media is not pleatable. You can also get coatings and membranes applied to the dirty side of the filter to help with dust release (PTFE membrane is one example often used for sticky dusts).
Big vs. little particles was explained to me in terms of rocks and sand by a gentleman who designed foundry baghouses for 30+ years. My understanding is that the big particles are like rocks, and the smaller particles are like sand. The rocks will hit the filter and knock some of the sand off. Also, if the rocks stick to the filter, they prevent the sand from embedding to deep into the filter. When the rocks are cleaned off, they take some sand with them and because they are heavier, more readily fall to the hopper. If you have only sand, it tends to pack tighter into the filter, is lighter, and more difficult to clean.
You hardly ever see a cyclone in front of a baghouse that is high efficiency unless it is to recover product. They are usually only there to reduce loading so the automated filter cleaning system (such as pulse jet) can keep up. In a typical home shop, the cleaning system is manual. The desire is to have longer time between filter cleanings. This is accomplished by separating most of the material before it can reach the filter, otherwise, the filter would fill up with chips and dust. The more efficient the separator, the less material carried over. The big pieces are the easiest to catch, while the small pieces are more difficult. Thus, with a high efficiency separator, only small particles are left to go onto the filter.
Contributor
Phil, in my opinion the error in your logic is that it isn't only the wood worker who suffers from poor dust collection, in many cases it's the family members as well.
In my case I have a basement shop, so it's worth putting the effort and money into clean air...............Rod.
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