New Whole Shop Outside Cycle Dust Collector Install

[tacks Y]

I ran bare copper wire along my pvc pipe to where I tie it to metal. I do get sparks on my dryer vent hose I clean the floor with.

[Andries]

If you put the bare copper wire inside the plastic ductwork and lead it out at some point, to one of your machines, it'll send the static charge away to ground.
For the vacuum cleanup or flexible hose, pick a hose that has a metal coil in it. Expose the metal coil and attach it to the copper wire or ground, and it won't zap you anymore either.

[tmbrcruiser]

Yes, I purchased Nordfab pipe and will change/add to present piping to complete the new connection. I'm looking forward to the upgrade, even getting a little excited. 

[YellowHammer]

I really don't want to stir a pot, but thought some people would like a little more reading to do, if they are interested.  Whether people use standard non conductive PVC pipe in their dust collector system, or use carbon loaded (conductive) or metallic pipe, is their decision, not mine.  I have used both.    

In my old job, I spent quite a bit of time working with, avoiding, and even analyzing the issues of static electricity in hazardous environments.  There are two scenarios involved in a potential dust collector fire and propagation - 1) the potential risk of fire inside the the duct, with flowing and dynamic air to fuel ratio, and 2) the potential risk of fire caused by single or repeated static sparks caused by triboelectric effect, (google it) to a fixed and suitably flammable material, such as sparking to a pile of very fine, highly flammable powder or vapor, outside the ductwork, in a static situation.  

I agree that the odds of a fire or explosion in a dynamic environment such as inside a flowing dust collector duct is minimal, as its extremely difficult to generate a one time spark that will happen to have the correct fuel air ratio to ignite a flowing combustable mixture.  I ran some experiments once, in my old job, where I injected natural gas, air, and eventually hydrogen into a dynamic and potentiality reactive particle environment with a single spark, and only after many, many tries (weeks), did I get any reaction at all.  We judged that a dynamic air and particulate incident was most likely not the cause of a major "in the news" facility fire, as it was almost impossible for me to repeat, even in artificial environments under laboratory conditions.

I also have no doubt, and industry agrees by implementing countless safety protocols in facilities and plants, sometimes labeling it is simply "good housekeeping" that repeatedly generating a tribolelectric spark and exposing a flammable material, such as a fine, dry flammable powder to spark energy, or flammable solvent vapors, will in fact, and has in the past, caused fires and loss of property, in many industries. A repeated and relatively high energy triboelectric spark, caused by a facility process (not feet dragging against carpet), can ignite a flammable material or vapor, if the arc happens to cross it.  The ignition source does not have to be sawdust, because the spark is external to the duct, but inside the shop, and if any flammable material in a shop gets between the spark, (vapors being probably the most common), a fire can be induced.  In this case, the sawdust flowing through a insulated pipe acts as a spark generator and can cause a spark to jump external to the duct, to a nearby conductive surface and can cause fires.  I have personally seen my old dust collector fire a repeated spark from the ductwork to a grounded surface, repeatedly, for hours, while I worked.  Only later, when it got dark, was I able to identify the location of the arc, which happened to be high up near the roof, luckily only near where fine dry, sawdust was piled.  Luckily I didn't start a fire, and it only happened two days in a many years of using the system, but it did happen, and was a repeatable, external event.  

Two completely different scenarios, two compeletly different levels of hazards.

When people think of "static electricity" such as dragging feet across carpet and causing a spark, that is a relatively low energy event, and is generally pretty safe.  However, working in my old job with explosives and propellant systems, personal induced electro static discharge has caused many catastrophic and deadly events, and that is why all explosive and propellant handlers are required to wear grounding straps or conductive shoes, at all times.  It's a cardinal rule.  Hand touch spark to some propellants, you are toast.  Hand touch spark to old school blasting caps, and every now and then, one blows your hand off.  I understand the rocket propellants and blasting caps are not sawdust, however, it does show that even a persons low energy static discharge can intiate a reaction is some circumstances.  These days, munition and explosives initiators are generally only deemed as safe if they are static discharge rated 1 amp-1 Watt safe, which is well above the normal static discharge from a human to a conductive object.  That's one reason you don't see the "Kids - don't handle blasting caps if you find them" TV commercials any more.  Remember those? The effects of static discharge haven't changed, only the initiator devices that were sensitive to them.  We don't use blasting caps anymore, we use much safer initiators that are basically immune to ESD.  

However, the effect of passing dry particles over conductive surfaces will cause a phenomenon called the "Triboelectric Effect" and it is a field or research that I have participated in occasionally, over the years.  Basically, as particles pass over an insulator, the insulator charges, and at some point, there is a dielectric breakdown of the insulator, and a potentially high energy spark will jump from the surface of the insulator to a conductive surface, much like jumping the gap of a spark plug.  If there happens to be a flammable substance between the spark, it may ignite.  This is a completely different level of energy from a barefoot/carpet spark, and many research papers have been written about it.  If the triboelectric charge was induced from a continuous process, such as two non conductive materials continuously rubbing together, then the charge and discharge cycle will repeat, and spark repeatedly, increasing the the chances of igniting a static pile of flammable material.  All triboelectric events are not high energy, but some are.  

Are there example of triboelectric discharges causing fires?  Certainly.  One of the most famous I worked on was the nuclear warhead capable Pershing Missile incident in Europe many years ago (Google it) where a Pershing missile was being removed from a container, and the atmospheric conditions were exactly correct.  As the non conductive case of the missile rubbed against another surface, at some point the friction built up enough charge (triboelectric effect) to cause a high energy spark resulting in the breakdown the insualtive nature of the motor case and subsequently cause an electrical discharge to the missile propellant, lighting it.  It didn't help this was during the Cold War, and the weapon system was not too far from a border.  It caused a tremendous international incident and killed several soldiers.  All from the process of two surfaces rubbing together causing a high energy triboelectric  discharge across a flammable material.  

I have personal experiences with others incidents, one of which was when the commonly available friction tape used to bind electrical leads together, was unwound.  As the tape was unwound from itself, it caused a very high energy triboelectric discharge that fired an initiator device.  The result were catastrophic.

Anyway, here is one of many documents that discuss the hards of tribelectrification in a facility environment.  Each to their own, each persons perception of risk is their own, and every persons decision is their own.  However, facility fires causes by triboelectrification are real, and in many cases avoidable.  Here is one short document that discusses some of the issues.  

Electrostatic Hazards: Early Warning Signs | Stonehouse Process Safety






 

[Andries]

Thank you Yellowhammer, that article was worth the read and was a great example of using plain language to illuminate a highly technical topic.
From that article;
With static so prevalent at home, do you really expect it to be absent at work? The main difference, of course, is that in the workplace, things happen at scale and with energy – and we also find extensive flammable atmospheres of low flash-point liquids or combustible powders and explosible dust clouds. An ominous combination.
The issue of woodworking dust collector fires seems to be one of scale, and as you mentioned, of housekeeping. 
A seed mill company in our city had erratic, but regular, dust explosions. The company blamed dust conditions and static discharge, and people were hurt. They were eventually charged with insurance fraud.  
A lifelong friend in Kenora has a friend that enjoys frequent shop wildfires. Not surprising when he does metal working and woodworking in the same space. The angle grinder sparks will fly and if those sparks find the six inches of sawdust under the corner of the table saw, well, excitement will ensue. His response to those episodes isn't to change his mo, but to buy more fire extinguishers. 
I have personally experienced a dust collector fire. My dad was a basement level woodworker and a smoker. He smoked a pipe and would often enjoy a puff and a coffee when contemplating his next masterpiece. His flame of choice was wooden kitchen matches and some spilled out of the box onto the floor. Yep, you can see this coming, right? A match got sucked into the dust collector and ignited as it went at high speed through the collector. He called me over late at night because he couldn't find the source of the smoke that was filling the house. Sawdust was smoldering and smoking between the basement wall and the bag. 
.
In spite of this mayhem, from my perspective, most of the Forum members are small scale woodworkers, sawyers or processors (firewood, moldings and the like) and will never experience a dust collector fire. Not from static spark at any rate. Real risk and percieved risk are sometimes worlds apart. Most woodworkers may have a cluttered workshop (a sure sign of a creative mind), but the real hazards are from the housekeeping side of things.
The benefits of a really good dust collector far outweigh the risks from static discharge, in my opinion.

[YellowHammer]

Yes, I agree.  A good dust collection system is extremely important for respiratory safety as well as getting as much sawdust out of the shop space to prevent any kind of fire, even from other scenarios. I remember years ago I was hanging out, watching a buddy sharpening a lawn mower blade with an angle grinder in his shop.  I watched a hot spark of metal land on a years old pile of sawdust on the shop floor, and poof, up it went like somebody lighting a campfire with flint and steel.  The guy whose shop I was in wasn't much on sawdust safety but he did have a fire extinguisher handy and we laughed about it later.  

The benefits of a good dust collector of any kind outweighs the risks of a possible fire, in my opinion and practice. However, there are things that can be easily done to reduce any chances of ignition to other sources, such as using TEFC motors, proper circuit breakers, proper wiring, proper grounding, and non conductive pipe, if available.  Typically, such plastic is black or dark colored and simply made with a small percentage of carbon, which is electrically conductive. 

[DR Buck]

This whole continued myth on PVC shop dust collectors really ticks me off when people without facts continue to spread false information.   I would have expected that here on the forum it would not continue.    But is does.   

I posted a video up in this thread that goes through a comprehensive explanation of why PVC is perfectly safe.    There have also been studies to try and prove PVC duct work is not safe.   Oneida, who sells duct collector systems and metal duct work tried and failed.  They have all failed.    

There are ZERO documented cases of ANY fire or explosions caused by PVC ductwork used in a wood shop.    

Here is a link to a very well written detailed article that supports this:    http://www.woodcentral.com/articles/s...  


    

[YellowHammer]

I've actually read the article many times, and it is limited in scope to "home dust collection systems" of which are defined, clearly, in the article, as under 1500 CFM, which is a very small system indeed, less than 1/3rd the performance of my earlier dust collection system, and considerably less still than my new system. It is also considerably less than what is used by some of the Forum members who are contributing to this topic.  So, in reality, the "myth" of an intrinsically safe dust collector system ends at 1500 CFM, which has no relevance to my system at all.  So in any case, the article and it's conclusions do not apply to me, due to the size of my system.  What does apply?  The National Fire Protection Safety (NFPA) Codes.  

From the article, "To my knowledge, there has never been a documented case of an explosion with PVC in the home shop, or a case of an explosion in a filter bag bag in a home shop."  A home shop is being defined in the article and the NFPA safety codes in part, as under 1500 CFM.  Mine and some of the others in this topic have many multiples of that.

So let's discuss this.  Here is the an important part of the article, so much so that it is highlighted in red by the author.  "It is important to note that the NFPA codes only apply to systems that move more than 1500 CFM or greater.  Despite advertising claims, none of the systems generally available for home use...come close to 1500 CFM."  

So here are two very important subjects to discuss.  My system is sold and classified as an "Industrial Dust Collection System."  Definitely not a home system under 1500 CFM.  In fact, it is many times larger than 1500 CFM.  What does that mean?  It falls under NFPA and OSHA regulations for flow rate requirements, assuming other site conditions are met.  It means that when I get my yearly and mandated inspections by the Fire Marshall, my system has to meet all NFPA codes that I fall under, or I may fail the inspection and get shut down.  Then since my insurance requires that I have a successful annual fire inspection, I lose my insurance.  This obviously is a very important couple reasons for me to not use PVC ducting, especially as I'm a business.  Quoted from the same article "The NFPA codes...call for grounded metal ducts.  Also, I think it's important to note that the NFPA codes only apply to systems that move more than 1500 CFM or greater."  Again, a very, very important piece of information.    

On to the second point, whether a home dust collector actually flows 1500 CFM.  The author states "It is important to note that the NFPA codes only apply to systems that move more than 1500 CFM or greater.  Despite advertising claims, none of the systems generally available for home use...come close to 1500 CFM."  This is a very problematic statement.  Whether or not the author believes many dust collectors are over rated, there is only one piece of equipment information that is relevant to an NFPA inspection (assuming other criteria are met), and that is the rating on the blower.  If it says it exceeds 1500 CFM, then it will fall under NFPA rules, unless the actual calibrated airflow can be determined.  So in most cases, it would be reasonable to assume that any safety inspections would be based on the motor and system capability plate riveted to the blower, not on a subjective statement from the shop owner of "Well, I think its over rated..."

Why does the NFPA care?  What's the point?  Well, it simply depends on the size of the dust collector system.  Quote from "Designing your dust collection system to meet NFPA standards — Part I, Gary Q. Johnson, Workplace Exposure Solutions" ---"About 40 percent of combustible dust explosions reported in the US and Europe over the last 25 years have involved dust collectors. Dust collection systems are now a primary focus of inspections required by OSHA's National Emphasis Program on safely handling combustible dusts."  If this document is read, it will immediately become apparent that a proper dust collector system is highly regulated in the larger systems, including flow losses, blast gate sizes, etc.  It is for this reason I had my system professionally designed.

Also, as I mentioned earlier in another post, there are several scenarios for dust collector induced fires, only one of which is the ignition and explosion inside the dust collector pipe or system.  Other problematic causes are from external sparks lighting flammable materials and vapors.  These occurrences can be greatly reduced by proper housekeeping.

Oh, by the way, from a real life standpoint, many people know that I get some of my wood planed at an offsite commercial facility.  In fact, earlier in this year, they blew the explosive release vent off their dust collector and were down for 2 weeks while they awaited repairs.  There is typically only one reason the explosive safety vent blows off a dust collection system.  Yes, it is a commercial system, but it is also worth noting that dust collector explosions can and do occur, otherwise commercial systems wouldn't have safety blast vents on them to begin with.  So I believe it's important that any such discussion involving dust collector hazards should always also referenced the size of the system and its relevance to national safety standards.

Can a dust collector fire happen, either internally or externally? Yes.  Is it of concern in a small shop, with a dust collector rating or actual CFM of under 1500 CFM?  Probably not.  Is it a concern with a system with over 1500 CFM?  Yes, enough so that it falls under NFPA regulations if other site conditions are met.  Is it a concern in a commercial application with commercial insurance?  Yes.  Is it a myth?  No, the facts are out there and readily available.  

Get the codes, read the codes, follow the codes.  If you don't fall under the codes, read them anyway so you can follow "best practices."

To paraphrase a popular TV commercial ......."What is in your shop?"  
 

[Walnut Beast]

Good read Yellowhammer 👍. Probably would be wise to just use metal piping system. Better to be safe than sorry 

[Brad_bb]

Robert, I am interested in the fine dust collection.  Are there pleated filters on that system? Are they after the blower or before?  How and how often are you needing to clean those filters.  That's the part I'm worried about getting a similar but maybe smaller system.  If you're protecting your lungs by catching the fine stuff, if you have to blow them out, you'll still get very dirty and will be a messy job, no?

[YellowHammer]

They are offered, but I didn't buy them because they are generally such a mess to clean, and won't hold up in an outside environment.  I don't know how long the time is between cleanings, but since there are three pleated filters, each about 5 feet tall, I can only imagine it's not a fun job at all to clean the fine dust filters. 

[Brad_bb]

So then your fine dust just exhausts into the outside air?

[YellowHammer]

 

 
Yes, I originally had an open port from the blower, but it was pretty loud, so I put a plenum and 3 foam sound attenuators on the output side.  Normally, this is where the 3 stack pleated filters mount, but you can see they aren't installed.  This helped reduce the sound significantly.  Basically, the air exits the blower straight down, and none of the fines get filtered out.  They exit about 10 feet from the building, and I never see them again. 

I've had other dust collectors with fine filters and cleaning them always left me looking like I'd rolled in flour, covered in dust.  I hated it.  Of course, I can't clean the air filter on my tractor without getting dust on me, much less 3 pleated dust collector filters, each about 5 feet long.  

I'm not sure how long they would need to run before they needed cleaning, but as much as we use ours, I'm sure I would have had to do it once by now.    

[tmbrcruiser]

I purchased the system with a return to four filters and a barrel that is under the filters. I believe I will be able to clean the filters without removing them. Using an air hose to blow and shaking the pleats at the same time. My understanding is I will be able to dump the finds from the barrel when full. Piping has arrived but, still waiting on the rest of the equipment.

[Brad_bb]

Yes if you have to blow out the fine filters and get it all over you and breath it in, kinda defeats one of the primary purposes - to protect your lungs.  If, as tmbrcruiser indicates, you have a system with a catch bin underneath, and the process of agitating the filters is mechanical so that the filters never need to come off, that would be the best.  Of course this would be if you are exhausting your air indoors to not lose heat or cool.

[Larry]

Bigger shops have a bag house with a shaker.  When they shake the bags the dust falls into trough with an auger that brings the fines outside.  You could rig up something similar on a small system.

I like YellowHammer's idea.  I also exhaust outside with a small blower and on a still evening my neighbor a 1/2 mile away can hear it.

[DR Buck]

Yes if you have to blow out the fine filters and get it all over you and breath it in, kinda defeats one of the primary purposes - to protect your lungs.  If, as tmbrcruiser indicates, you have a system with a catch bin underneath, and the process of agitating the filters is mechanical so that the filters never need to come off, that would be the best.  Of course this would be if you are exhausting your air indoors to not lose heat or cool.

On a smaller scale my dust collector does just that.     There is a low RPM motor that has a long shaft that protrudes the length of the filter.   The shaft has several nylon or some sort of plastic tabs that extend out from the shaft up against the inside of the filter pleats.  When the collector is powered off, the the filter cleaning motor rotates one direction for about 15 seconds, stops, then goes the opposite direction for the same amount time.   This knocks the dust from the filter down into the bag on the bottom.     I empty the bag every few months, or more often if I don't pay attention to the 'Full Barrel" alarm and then the bag fills up with shavings and large dust.  :    I have had this collector for 15+ years and have never had the filter off.





 

[tmbrcruiser]

The system I have now has three filter with small motors that rotate in both directions to clear the filters. The one of the problem with that system the filter are rubbed in the same place and soon wear. But I never have a problem fine dust in the shop air. Seems every system has it's pro's and con's, so we all end up picking a system what works best for our individual needs. The best thing about this forum lots of experienced advice.

[RussMaGuss]

So looking at this fancy system with the rotary airlock and everything has got me thinking. Instead of attempting and failing to DIY my own rotary airlock for my grizzly 3HP cyclone, what do you guys think about this: wall mounting the cyclone up higher, cutting a hole in the bottom of the barrel and adding a big blast gate to a chute that leads outside of my garage. That way, when it fills up, instead of farting around with emptying and replacing the bag for 5 minutes, I can just have it dump into a 275 gallon box that I can then take to my mill scraps area and dump/burn. I am thinking this would be my best option since I am looking to save shop floor space and decided against having it being outdoors. I'm mostly wondering on how airtight the blast gate would have to be to maintain a solid vacuum in there. 

[YellowHammer]

The blast gate has to be pretty tight, since its on the suction side.  However, you could do exactly as you suggest, as long  as the opening in the bottom of the collection barrel is large enough for the sawdust not to jam up or clog the opening, or while it's feeding.

You could also use a smaller blower as a transfer blower, maybe an old dust collector blower you are not using, and just suck out the dust in the barrel when it gets full.  That way the blast gate on the bottom of the drum maintains a seal, and then when it's opened, the transfer blower can suck out the sawdust.

[tmbrcruiser]

I received the equipment from Oneida (20hp cyclone with filters, air lock and transfer blower) about two weeks ago. Shop has been a mess putting the equipment together and figuring out the exact placement/piping. Tomorrow concrete is scheduled for 10:00, looking forward to the new system. Hope to post some pictures as we set equipment.

[tmbrcruiser]

 

 

 

 

 

 

 

The Laguna collector is being replaced by the equipment from Oneida. The Laguna is a good collector but dumping the bin slows down the shop a lot. The cyclone is outside in an equipment bay and the transfer blower will sit on small pad outside (to the left). The return filters will sit inside the shop at about the same place as the Laguna collector. 

Looking for a 16' dump trail, covid has all the trailer sales lots out of trailers to sell. Several dealers said they would have new stock in about three weeks. Will build a box over the dump trailer, that should hold about 750 cubic feet of dust/shavings. The bin under the Laguna collector hold about 45 cubic feet and when I'm running flooring fill that bin in about 20 minutes. That is the reason for the upgrade.

Plan is to connect the electric and all of the duct work from the air lock to the transfer blower. Last thing will be to change duct and connect filters in the shop. Hoping this will only shut down the shop for a day or two.  

[YellowHammer]

That is a sweet setup.  Your filters stand up with a bin under them.  Thats opposite of how mine were, thats why I didn't get them.  I like your setup.

[Walnut Beast]

Very nice 👍. What's the hp of your setup 

[Walnut Beast]

I see that it's 20 hp. WOW