Bill Pentz and Cyclone Test

[Alan Simpson]

I think, if the filters are deficient, then the last phase of Bill's test (waiting for a return to safe levels with no cutting but DC running) will take forever or will never happen. It is during this phase that they are essentially using the DC as an air filter, and the suitability of the hood is pretty much out of the equation.

It is possible for the hoods to also be deficient and for that to be detected earlier by the detection of larger particles during the cutting tests. Larger particles suspended in the air would indicate that these particles are getting past the DC altogether.

Excellent point Phil. Of all the people who have reported their results of Bill's testing, they all mentioned how quickly their DC returned the air quality to the baseline after cutting ceased (by leaving the DC on). To me, that directly contradicts Bill's claim that "this testing is showing the huge numbers of very fine particles that are going through the filters". As you stated... if this were true, the air quality would NEVER return to the baseline.

[Don Baer]

Robert,
I can't speak for the other question because I wasn't with Bill doing the testing but I can speak about the equiptment he is using. It is a GT 531 Particulate counter from Met One Instruments. The reason I know this is because Bill asked me for a recommendation of the types of instrument to use and this is the one I recommended. I met the folks at Met one at the last AIHCE show in Chicago and found that it is just the ticket for doing portable survey work like Bill is doing. If you would like more information feel free to PM me or go to there web site.

Just a side note I don't work for Met one I am just a happy customer.

[Phil Thien]

Excellent point Phil. Of all the people who have reported their results of Bill's testing, they all mentioned how quickly their DC returned the air quality to the baseline after cutting ceased (by leaving the DC on). To me, that directly contradicts Bill's claim that "this testing is showing the huge numbers of very fine particles that are going through the filters". As you stated... if this were true, the air quality would NEVER return to the baseline.

Right, and I have a problem with citing values like "huge numbers" on so many levels it isn't even funny.

[Jim O'Dell]

Excellent point Phil. Of all the people who have reported their results of Bill's testing, they all mentioned how quickly their DC returned the air quality to the baseline after cutting ceased (by leaving the DC on). To me, that directly contradicts Bill's claim that "this testing is showing the huge numbers of very fine particles that are going through the filters". As you stated... if this were true, the air quality would NEVER return to the baseline.

Do I gather from your post, then, that you feel the problem is at the point of collection? If so, I think that is a good point. (If not, let me make that point here ) I know Bill Pentz devotes a pretty good section of his site to pick up hoods. Other sites touch on it as well. So, who has a good handle on pick up hoods for different types of machines? I'm really amazed that with the prolifferation of cyclones in todays market, that more of the distributors don't push for 5", or prefferably, 6" hook ups on their table saws, jointers, bandsaws, etc. And while there are some aftermarket pick up hoods for mitre saws and contractor saws and such, I don't see manufacturers stepping up and developing these for their specific tools. I'd like to see even adjustable air inlet holes via a slide like a blast gate to adjust for the air flow within a specific tool. (To collect the dust and chips, you need air flow, not suction)This should be easy to do on a TS or Jointer. Properly positioned, it would allow the air to then flow across the Blades(s) and on into the pick up tube for optimum collection.
Anyway, just some thoughts since I'm house bound today. Jim.

[John Renzetti]

[QUOTE=Robert Witter]Bill,
[

I have always read that wood dust is not particularly small as dusts go. Only a tiny fraction of the airborne wood dust is sub micron.
I will site a wood shop air sampling study from University of Vermont , Burlington VT Dept of Epidemiology and Environmental Health.
They ran 13 different machines: belt sanders, drum sanders, routers, shapers, and various saws classified the airborne dust by size. 22.5, 14.1, 5.5, 3.2, 2.0, 1.2 Microns

For Example:
In 9 tests they recorded zero % of the material was below 1.2 micron in size. On 4 tests the amount of dust below 1.2 micron was one tenth of 1 % of the total air borne material. By weight.


Also, It looks like the amperage and CFM tests reported by clear vue owners show that they run only about 10.8 Amps @ 230V for 1100 CFM. This is only half the amp rating of a 5 HP motor.
This is well within the limits of a 2HP 11- 12 Amp motor at 1100 CFM. Are these reports correct? If so why are you running a 21 amp 5HP motor to get 1100 CFM and wouldn’t a two or three HP accomplish the same thing?

Hi Robert, Good points and information. The tests of dust particle size is interesting. However wouldn't particle size especially the submicron size be determined by the material being processed. I know mdf produces some nasty dust. Also sanding grit would also have an effect on particle size. That's why I feel that the choice of filters should depend on the type of wood processing being done. And of course the individual involved, as some are very sensitive to any microscopic wood dust. I use a dust collector (European) that has a BIA rating of whatever Class C or G. I still use a JDS shop filter and when I feel it necessary I use a mask.

With regard to motor hp/amps draw/cfm, doesn't the amp draw of a motor increase as more blast gates are open. So if the 5hp in the clearview is drawing 10amps, it just means that's all it needs, and it's not working as hard as it could, and has plenty of reserve power. A 2hp motor drawing 11 amps is working a full capacity and if you opened up more than one blast gate you'd be in danger of overheating the motor since the motor will draw the amps demanded. Some motor manufacturers will show in their technical data the power produced at various load demands up to 150%. The motor can produce 150% of its rated power, but it just won't last as long.
Thanks for the great input and for helping to keep this debate/discussion on a lively but not overheated level.
take care,
John

[Ed Morgano]

I have always read that wood dust is not particularly small as dusts go. Only a tiny fraction of the airborne wood dust is sub micron. Where did you read that?
I will site a wood shop air sampling study from University of Vermont , Burlington VT Dept of Epidemiology and Environmental Health. Do you have a link to a website where we can obtain the information about how this study was conducted?
They ran 13 different machines: belt sanders, drum sanders, routers, shapers, and various saws classified the airborne dust by size. 22.5, 14.1, 5.5, 3.2, 2.0, 1.2 Microns Does this mean that they weren’t looking for anything smaller than 1.2 microns? What did they use to look for the particles? Did they have equipment that could “see” particles smaller than 1.2 microns?

For Example:
In 9 tests they recorded zero % of the material was below 1.2 micron in size. On 4 tests the amount of dust below 1.2 micron was one tenth of 1 % of the total air borne material. By weight. There are 8000 .5 micron particles in one10 micron particle (10/.5 = 20, 20^3 = 8000)…..By weight. So, if you had the equivalent of 12.5 10 micron particles, it would take 100,000 .5 micron particles to weigh the same amount. Maybe that is why Bill is getting such high particle counts?

[lou sansone]

I have always read that wood dust is not particularly small as dusts go. Only a tiny fraction of the airborne wood dust is sub micron. Where did you read that?
I will site a wood shop air sampling study from University of Vermont , Burlington VT Dept of Epidemiology and Environmental Health. Do you have a link to a website where we can obtain the information about how this study was conducted?
They ran 13 different machines: belt sanders, drum sanders, routers, shapers, and various saws classified the airborne dust by size. 22.5, 14.1, 5.5, 3.2, 2.0, 1.2 Microns Does this mean that they weren’t looking for anything smaller than 1.2 microns? What did they use to look for the particles? Did they have equipment that could “see” particles smaller than 1.2 microns?

For Example:
In 9 tests they recorded zero % of the material was below 1.2 micron in size. On 4 tests the amount of dust below 1.2 micron was one tenth of 1 % of the total air borne material. By weight. There are 8000 .5 micron particles in one10 micron particle (10/.5 = 20, 20^3 = 8000)…..By weight. So, if you had the equivalent of 12.5 10 micron particles, it would take 100,000 .5 micron particles to weigh the same amount. Maybe that is why Bill is getting such high particle counts?

well just a casual reading of this journal article housed at the NIH seems to indicate that the majority of particles are in the 1 to 10 micron range.

http://ntp-server.niehs.nih.gov/ntp/...s/s189wood.pdf

another more confusing paper seems to show a large concentration of diameters in figure 4 in the 10 micron range.
It looks like both journal article offer good references for other research that you might find useful
http://www.rsc.org/delivery/_Article...JournalCode=EM

Lou

[Ed Morgano]

What I was pointing out and your first journal article also finds is that there are particles of .5 micron size and that it takes many thousands of these particles to equal a few larger particles. Bill may have said that the "particle count" was 100,000 times more than safe levels......not that the quantity of dust was 100,000 times safe levels. There is a large distinction to be made between the number of particles in the air and the mg/m^3. Also as your journal article points out, ......"Particles with a diameter larger than 5 µm (“inspirable” particles) are deposited almost completely in the nose, while particles 0.5 µm to 5 µm in diameter (“respirable” particles) are deposited in the lower airways."

In the second journal article that you mentioned they distinctly said that they made a compromise as to the size particles they could look at.

"Limit of detection and blanks
There is a trade-off between the magnification and the area of
view, such that in order to properly measure particles greater
than 100 micron diameter, it is necessary to reduce the magnification
so that these particles are completely within the field
of view. The 206 objective is the compromise. The limit of
resolution of the microscope imaging system at this magnification
is about 2 microns."

Ed

Post revised to clarify which journal link I was quoting from.

[lou sansone]

hi ed
I am not arguing from a specific POV, but this thread caught my attention and just a little digging sort of shows that John R's assertion that sub-micron particles due to wood working are not typical, as the first article cited indicated. The quote you captioned in the previous response only indicates the typical place of residence of particulate size, and not the fact the in wood working 0.5 micron particles are generated on a regular basis. The actual distribution cited in the first article reads :

"Total airborne dust concentrations are described as mass per unit
volume (usually milligrams per cubic meter). Wood dust generally is
collected by a standard gravimetric method that involves using a
sampling pump to collect a known volume of air through a special
membrane filter contained in a plastic cassette. Some sampling studies
reported that the particle size distribution varied according to the
woodworking operation, with sanding producing smaller particles
than sawing, but others found no consistent differences (IARC 1995).
The majority of the wood dust mass was reported to be contributed
by particles larger than 10 µm in aerodynamic diameter; however,
between 61% and 65% of the particles by count measured between 1
and 5 µm in diameter (IARC 1995)."

Is it possible that the collection and detection equipment is not sophisticated enough to collect and measure sub micron particles ? That could be. From your professional experience, what type of equipment has been used to gather sub micron particle size information ?

Where in the second article did you find :

"What I was pointing out and your journal article also finds is that there are particles of .5 micron size "

?

IRT the second article there is an obvious reasoned choice as to the range of particles to captured and analyzed. One could take a reasoned positioned that the researchers understood sub-micron particle size wood dust is not typical and therefore designed the experiment to capture the vast majority of wood working generated dust particles in the micron range and not the sub micron range. Again I would refer you to figure 4 in the second article for a crude distribution of the particle size. They are clustered in the micron range and not in the sub micron range. I think john's point stands, but enjoy reading journal articles and welcome addition data.

Lou

[Tom Jones III]

Arguing about whether there are "a lot" of the smaller particles is absolutely pointless without having a frame of reference. Answering 2 questions is requisite for an intelligent discussion on this topic.

* First what is a measure of the smaller particles that is known to be harmful to human health? If only a very small number of particles is known to be harmful then the research may be correct that there are very few particles generated, but if the very small numbers could kill you then that changes the discussion.

* Second what is the baseline of the smaller particles? Combine this answer to the answer to the first question to form an objective goal for air quality. How many of these small particles are in the air in my house, my office, the park? I don't think I want to know what I'm breathing during a 60 minute run through Houston but it would be useful to know how it compares to 60 minutes in my workshop.

[Ed Morgano]

Tom,
I'm most likely in the same boat as everyone else on your first question......What level is actually harmful to your health? Three standards already exist and I'm sure over time that more data will be accumulated to show which of these standards is actually necessary to protect our health and to what level.
On your second point, I agree completely. That is why I think the testing that Bill Pentz is doing will be useful. He is taking base line measurements right outside of each shop that he tests. Bill has put a lot of effort into doing these tests and I think he should be thanked for his efforts.

[Jay Albrandt]

Mr. Witter,

You mis-quote what I said.

Please reread my first post. I clearly state that I am a layperson and my report of Bill's findings were MY interpretation (not Bill's) of a TON of information that I am still trying to wrap my brain around. In statement #2 of my first post, I said that there were 100,000 MORE residual particles in the air when compared to the outside air...........NOT 100,000 TIMES more particles. The actual readings from Bill's instruments showed that the ambient air outside my shop had 134,520 particles in the 0.5 micron and below range and 3,820 in the 5.0 micron range and below. The residuals inside my undisturbed shop were 144,290 and 1,940 respectively.

Furthermore, and I mean no disrespect to Mr. Pentz by admitting this, but I was very skeptical about the little machine he used to test my shop air. During the test I wrote down the name and model number of the device and called my friend who has a degree in environmental health and who works for the City of San Diego. I gave him the whole story and he was amazed that some guy bought this device himself. He said the machine is very expensive and that it is very acurate. Why do I bring this up? Bill is the first one to do what he is doing, he is spending his own money and time doing it, so lets give him a break and wait until he finishes and compiles the information before we try to compare how his findings differ from other studies that were probably done under different conditions.

Peace,

Jay

[Phil Thien]

Mr. Witter,

You mis-quote what I said.

Please reread my first post. I clearly state that I am a layperson and my report of Bill's findings were MY interpretation (not Bill's) of a TON of information that I am still trying to wrap my brain around. In statement #2 of my first post, I said that there were 100,000 MORE residual particles in the air when compared to the outside air...........NOT 100,000 TIMES more particles. The actual readings from Bill's instruments showed that the ambient air outside my shop had 134,520 particles in the 0.5 micron and below range and 3,820 in the 5.0 micron range and below. The residuals inside my undisturbed shop were 144,290 and 1,940 respectively.

Furthermore, and I mean no disrespect to Mr. Pentz by admitting this, but I was very skeptical about the little machine he used to test my shop air. During the test I wrote down the name and model number of the device and called my friend who has a degree in environmental health and who works for the City of San Diego. I gave him the whole story and he was amazed that some guy bought this device himself. He said the machine is very expensive and that it is very acurate. Why do I bring this up? Bill is the first one to do what he is doing, he is spending his own money and time doing it, so lets give him a break and wait until he finishes and compiles the information before we try to compare how his findings differ from other studies that were probably done under different conditions.

Peace,

Jay

Either I'm missing something or those #'s don't add up. If the actual readings from Bill's instruments showed that the ambient air outside your shop had 134,520 particles in the 0.5 micron and below range and 3,820 in the 5.0 micron range and below, and the residuals inside your undisturbed shop were 144,290 and 1,940 respectively, then where is the 100,000 difference?

Had you intended to write 10,000 instead of 100,000?

[Alan Simpson]

By residual particles, are you referring to the particles in your shop air before or after cutting???

[Ed Morgano]

By residual particles, are you referring to the particles in your shop air before or after cutting???

Alan,
He said: "The residuals inside my undisturbed shop were 144,290 and 1,940 respectively...." so I think he means before cutting.

Ed