Central Shop Vac System

[roger wiegand]

For the same reasons that we didn't put a central vac into our new house (having had one in the prior house) I wouldn't. The problem is that for me, and for my wife in the house, the discomfort of storing and hauling around a long hose far exceed the discomfort of dragging a small shop vac around where it's needed. The central vac hoses are heavy and bulky and a general PITA, taking up significant storage space. Your mileage may well vary.

[Peter Aeschliman]

Alan, Glenn, thank you for your insights.

Alan, every time you post about your shop, and particularly your DC system, I'm mesmerized. Makes me wish I had studied engineering rather than accounting and finance!

Truly inspiring stuff.

Clearly I have some homework to do on vacuum systems. Thanks again everybody for your contributions to this thread!

[Mike Chalmers]

Absolutely I was being sarcastic. Dust Collection as advocated by Mr Pentz is an exacting science that will brook no reduction to the absolute best. Most folks do not come anywhere near what is advocated on his website. I would say that the acceptable standard is a personal decision, and is certainly tied to what people can afford. Even if I were to concede that his research and conclusions are 100% correct (and I am not), what one is willing to accept as good enough varies greatly. I, for one, feel that my 2 HP canister equipped one stage with a Super Dust Deputy running direct to one tool at a time is more than acceptable. I also have three shop vacs of various power equipped with dust deputies that hook direct to the tool I am using at the time. An air cleaner with a series of fans circulating the air around the shop I am quite confident that my dust collection is pretty good, and the amount of dust on flat surfaces bears that out. I know folks will say Fine, but the stuff you have to worry about you can't see. This makes no sense to me. The smaller the particle, the lighter it is. The lighter it is, the easier it is for the air to move it. So, if you are capturing big particles, stands to reason you are catching the smaller ones. Of course, the quality of the filter will have a significant influence there.

[John Donhowe]

At the risk of 1) being the dunce of this thread twice over; and 2) hijacking the thread,

Mike- I agree completely with your perspective on dust collection. The only quibble I have the reasoning about small particles.

I know folks will say Fine, but the stuff you have to worry about you can't see. This makes no sense to me. The smaller the particle, the lighter it is. The lighter it is, the easier it is for the air to move it. So, if you are capturing big particles, stands to reason you are catching the smaller ones. Of course, the quality of the filter will have a significant influence there.

Fine particles are riskier precisely because they stay suspended in the air longer- they're more likely to be inhaled, pass through your trachea and bronchi. all the way to your lung tissue. IIRC, the total surface area of healthy lungs is equal to a tennis court, so there's a good chance they can find a place to stick there, where they do the most damage.

A filter with large pore sizes will trap big particles, but let small ones through (until it becomes so caked that nothing passes through, at which time it's no longer a filter!).

BTW, these are great posts of shop set ups to which I can aspire.

[Peter Aeschliman]

Absolutely I was being sarcastic. Dust Collection as advocated by Mr Pentz is an exacting science that will brook no reduction to the absolute best. Most folks do not come anywhere near what is advocated on his website. I would say that the acceptable standard is a personal decision, and is certainly tied to what people can afford. Even if I were to concede that his research and conclusions are 100% correct (and I am not), what one is willing to accept as good enough varies greatly. I, for one, feel that my 2 HP canister equipped one stage with a Super Dust Deputy running direct to one tool at a time is more than acceptable. I also have three shop vacs of various power equipped with dust deputies that hook direct to the tool I am using at the time. An air cleaner with a series of fans circulating the air around the shop I am quite confident that my dust collection is pretty good, and the amount of dust on flat surfaces bears that out. I know folks will say Fine, but the stuff you have to worry about you can't see. This makes no sense to me. The smaller the particle, the lighter it is. The lighter it is, the easier it is for the air to move it. So, if you are capturing big particles, stands to reason you are catching the smaller ones. Of course, the quality of the filter will have a significant influence there.

Gotcha. I understand your perspective.

100% agreed that it's a personal decision. For my personal decision-making process, what's most important to me is making a fully-informed decision. I think one of the saddest scenarios is when people make decisions passively and end up having to live with negative consequences they did not anticipate (but could have if they had done their research). It sounds to me that you have educated yourself and have made your decisions from your base of knowledge.

As for shop vacs, which is the topic here, it is not my main source of dust collection. I have two big Wynn environmental filters that I fitted fans to to filter and circulate air, an additional Jet air scrubber, a 3HP grizzly motor with a 15" impeller on an Ebay cyclone and 6" main duct (this is my trade off- Pentz recommends much more power than this), and my shop vac with a dust deputy. My ROS is the only tool that I use with my shop vac that produces lots of dust.

I did buy a dylos on a whim because I'm a data-driven kind of guy. That's my way of making an informed decision- without the dylos, I don't really know if my approach is working. My personal tendency is also to err on the side of caution when it comes to health-related risks.

To each his own for sure, and I get your reaction to (what often seems like) the Pentz "following."

[Phil Thien]

The only quibble I have the reasoning about small particles.

Fine particles are riskier precisely because they stay suspended in the air longer- they're more likely to be inhaled, pass through your trachea and bronchi. all the way to your lung tissue. IIRC, the total surface area of healthy lungs is equal to a tennis court, so there's a good chance they can find a place to stick there, where they do the most damage.

Dust of an respirable size is certainly the most dangerous, but Mike is right, it is actually easier to entrain the finest stuff in your DC airflow than heavier stuff.

And the Dylos meter group buy showed us that the finest dust DOES settle (fairly quickly, too). The notion that our workshops are toxic wastelands of never-settling super-fine dust was simply a scare tactic.

Finally, air scrubbers of any sort (just running a cartridge-equipped DC with a couple of gates open) will do WONDERS for air quality.

[Alan Schaffter]

Mike, there is validity to some of what you say with regards to economics, and though some will try, no one can argue with what any person personally considers or "feels" "acceptable" or "more than acceptable," whatever that means. But there are a few areas where you miss the mark.

Air cleaners can help sometimes. . . . but they will only filter air that passes through them and only to the degree determined by the effectiveness of the filter media. Sometimes the don't. By "circulating the air" they help the fine dust which can stay airborne in excess of 30 min. on its own, stay airborne a lot longer, giving the woodworker ample opportunity to inhale it.

It has been widely documented by Healthcare and Environmental Health professionals that the most dangerous dust to breathe is in the .5 to 10 micron range. The majority of particles larger and smaller than that are too small to do any damage even if trapped in the aveoli of the lungs. Larger particles are captured in the windpipe mucous and expelled or easily aspirated.

A quick Google search will yield a graphic comparison of that size range to the size of a human hair (it is an eye opener!) and also confirm that dust in that range can't be seen until there is substantial surface accumulation. One of the only adequate ways to determine how much of what dust particles are being collected or not collected is to test the air in your shop with a Dylos particle meter before, during and after woodworking operations and compare the results with the various OSHA, EPA, ALA, etc. recommended exposure limits.

The major problem with a loaded single stage DC that is not designed to be used with a cyclone or cartridge filter or a shopvac is that, depending on the installation, they may fail miserably to capture fine dust as it escapes from larger machines. The just do not supply the CFM necessary to do that, especially through a 2-1/2" hose for a machine that generates a large amount of dust. They have a hard enough time just collecting from small power tools. Cylones, separators, and filters are after-thoughts, and only important if you try to recirculate the air back into your shop- something that industry rarely attempts to do because it is difficult and expensive.

Finally, I hope you are wearing good ear protection. With the exception of Festool and maybe the Fein, most shopvacs are very loud and generate enough decibels to result in permanent hearing damage with even moderate use.

As long as the user vacuums off his clothes and exposed parts of his body before leaving the shop, he will receive better dust protection from a good mask than from any dust collector or multiple dust collectors.

[Mike Chalmers]

Air cleaners can help sometimes. . . . but they will only filter air that passes through them and only to the degree determined by the effectiveness of the filter media. Sometimes the don't. By "circulating the air" they help the fine dust which can stay airborne in excess of 30 min. on its own, stay airborne a lot longer, giving the woodworker ample opportunity to inhale it.

The fans I have set up around my shop make the air borne particles move to my air cleaner, which has a 1 micron filter. My shop is arranged so that the airflow is from the tool and away from me while I am operating it. As I move from tool to tool, the air flow should have moved the vast majority of anything that escapes my dust collection devices away from the work area.

It has been widely documented by Healthcare and Environmental Health professionals that the most dangerous dust to breathe is in the .5 to 10 micron range. The majority of particles larger and smaller than that are too small to do any damage even if trapped in the aveoli of the lungs. Larger particles are captured in the windpipe mucous and expelled or easily aspirated.

One of the only adequate ways to determine how much of what dust particles are being collected or not collected is to test the air in your shop with a Dylos particle meter before, during and after woodworking operations and compare the results with the various OSHA, EPA, ALA, etc. recommended exposure limits.

I am just not that concerned. I am happy that my shop stays pretty clean, and that I cannot feel sawdust when I breathe. Even my sanders are hooked to Shop Vacs with a dust deputy and a HEPA filter.

The major problem with a loaded single stage DC that is not designed to be used with a cyclone or cartridge filter or a shopvac is that, depending on the installation, they may fail miserably to capture fine dust as it escapes from larger machines. The just do not supply the CFM necessary to do that, especially through a 2-1/2" hose for a machine that generates a large amount of dust. They have a hard enough time just collecting from small power tools. Cylones, separators, and filters are after-thoughts, and only important if you try to recirculate the air back into your shop- something that industry rarely attempts to do because it is difficult and expensive.

Can't agree with that. I can feel the amount of air moving through the end of my 5" and 4" hose. Even more, I can see the results when I use it to do some clean up. Dust BE GONE! I do support that going down to a 2 1/2" hose with a DC does not work well. That is why there are Shop Vacs. A place for high volume, a place for strong suction.

As long as the user vacuums off his clothes and exposed parts of his body before leaving the shop, he will receive better dust protection from a good mask than from any dust collector or multiple dust collectors.

For me, this is in the same category as defensive driving. To be truly safe, the car never leaves the garage. Dust masks are a real pain, fog my glasses, cause me to sweat in them, distract me from safe practices. Again, what standard is acceptable is a personal decision. The answer is not as emphatic as you state.

[Bob Faris]

Another example of a vacuum-based system...

http://www.instructables.com/id/DIY-...ust-Collector/

[Alan Schaffter]

Can't agree with that. I can feel the amount of air moving through the end of my 5" and 4" hose. Even more, I can see the results when I use it to do some clean up. Dust BE GONE! I do support that going down to a 2 1/2" hose with a DC does not work well. That is why there are Shop Vacs. A place for high volume, a place for strong suction.

What you are feeling is velocity, not volume. You can easily prove it- just do the math. Or Measure the static pressure generated by the pipe, separator and filter. When you plot that on the fan curve that 800 CFM single stage DC is likely to be pulling only 200-300 CFM or less at the machines. Also, the cross-section area of the pipe determines the volume of air it will move, simple math will show that, or to see it with your own eyes, aim a spot light at a 4" DC intake, make a nice cloud of dust or smoke and turn off the lights as you turn on the DC. Now do the same thing with a 5" and a 6"intake. I guarantee the 6" intake will suck the cloud of smoke more quickly that the other two.

[Peter Aeschliman]

Reviving this thread- what do you guys think about venting the shop vac or central vac outside for air quality?

Even with my dust deputy, the the HEPA filter in my shop vac gets packed badly with dust faster than I would like (I use it for super fine sanding dust). So what if i simply remove the filter from my shop vac and connect the exhaust to a vent that leads outside?

This central home vac site seems to recommend it: https://www.centralvacuumstores.com/...nstall-venting

I'm planning a new basement shop and really don't want fine dust getting into the house. I want to do the same with my Cyclone (I've read all about furnaces and CO risks- don't worry, I'll do it right!)... my drum sander clogs my cyclone filters up crazy fast.

Is there a mechanical reason why I need filtered air running through the shop vac's impeller that makes it different than a dust collector?

[Peter Aeschliman]

Alright I think I'm going to answer my own question... the central vac manufacturers clearly differentiate the cyclone vacuum systems (which must be vented outside and are designed for no filters) from the others. One of those distinctions is that the fan/blower/motor unit is designed so that the dust doesn't get into the electronics.

This video makes that clear:



I suspect that it would kill my Shopvac if I removed the filter, even with a cyclone in front of it.

[Peter Aeschliman]

Sorry, diarrhea of the keyboard here... But while doing my research, I came across this super helpful page:

http://www.canavac.com/node/9

If my shopvac has a "flow through" motor, then I cannot remove the filter, because it's using the filtered air to cool the motor. Looks if I want to make use of my dust deputy cyclone and vent the exhaust outside, I might be able to just find myself a tangential bypass style motor and fabricate my own housing... interesting stuff.

[Ole Anderson]

I had a 6 gallon "Quiet" haha" Shop Vac, don't remember the hp. I replaced it last year with a 12 gallon Craftsman 5.5 (peak, haha again) hp 11.8 amp vac. What a difference! Like night and day. It was top rated in somebody's test with high suction and cfm, don't remember the numbers, that is why I went with that one. No regrets.

[Phil Thien]

I imagine some of the shop vac units that have detachable blowers already have the bypass aspect you seek.