sawmill shed exhaust fumes question

[Randy88]

I've done a lot of reading here and elsewhere about sawmill sheds, but hardly any of them discuss exhaust fumes and how they address this in their shed design.      

So for the people that saw in cold weather and want the shed to keep the wind and cold out, so its somewhat warm, how do you handle the exhaust fumes?

I know its been stated a few times, a couple keep fans running year round, most never state how they exhaust the fumes.   

We run a small dust collection system in the house basement and was wondering if I'd hook up a dust system for the mill and edger, if it were large enough, does this suck some, most or none of the exhaust out along with the dust?

I don't have three phase power, so using electric motors is not an option, been to a few that use only motors along with dust collection and its very nice.  

I've been doing a lot of research on the perfect sawmill shed, but got to thinking before doing something, I'd better address exhaust fumes first.   The way it is now, I'd be running three gas engines, two for the mill, one on the edger, not to mention a diesel skid steer to bring logs and shuffle edgings and lumber around and chainsaws doing trimming and edging cutup as we saw.  

I'm a poor weather sawyer, meaning when its raining, snowing, cold and miserable outside and I can't do anything constructive, we saw lumber, right now we do it inside a machine shed, but its a process to get setup and take back down to cram equipment back in, part is done inside the rest outside and can only do it with doors fully open.      What I'm wanting is to have a shed, more dedicated so to speak, with plenty of doors and access so as the wind changes we can open and close doors and do everything under a roof and when its frigid out, close everything up and keep sawing, so that's the major concern I have is when things are closed up??     Any help or suggestions would be appreciated, thanks

[doc henderson]

Hey Randy.  carbon monoxide (CO) is the big problem.  CO bind hemoglobin 200 x more effectively than O2. The antidote is high concentration O2.  room air is 21%.  so 100% O2.  Non smokers run between 1 to 5 %, and smokers run between 5 and 10%.  50% is lethal.  If you are in a tightly enclosed space so that forced air heat will work, big problem is running all those gas engines.  You could plan for radiant heat that works even with a little breeze going through.  catalytic models will degrade if there is too much exhaust in the air.  In floor pex works well and you can feel the heat, even in cold air.  think of the sunshine out side.  If you have employees you will have to be more commercial and follow OSHA guidelines ect.  You will prob. need to vent exhaust outside and monitor the air inside.  think of a big car repair shop with the hoses going through a plastic/silicone flex pipe through a hole in the garage door.  You will need more than a household monitor for the CO, prob. one that read actual percentages and can be checked and calibrated on a regular schedule.  A pulse oximeter, like used in hospitals and clinics will not work to check personnel.  It reads % of hemoglobin saturation and cannot tell CO from O2 saturation.  had an elderly man working at a car wash early one winter am.  He was cleaning the stalls by taking a gas powered pressure washer into each and closing garage doors front and back.  He died.  An individual will have symptoms but often these are ignored or not noticed and then it is too late.  be safe.

[POSTON WIDEHEAD]

Switch to an electric motor for your mill

[tawilson]

 

 
This was my solution.  I have wrapped three sides with RV screen room panels I had kicking around and just put screen in the area above that. The panels are vinyl with zippers I can open up and stop about a foot from the ground but there's enough ventilation so I only open up the end facing us in the pic in the summer. I have the lumber stacked to put 2 more of these together to cover the entire mill.

[TKehl]

I wouldn't rule out electric yet.  What kind of HP are you talking?  Generally if you take the nameplate gas hp, divide by 2 and round up to the nearest electric motor size it will work just as good.
 
Also, with three gas engines, replacing them all with 3 phase motors and running a generator (engine or tractor powered) would be an option.  May even save money long term.
 
I would be thinking of ways to use conveyors to shuffle logs, edgings, and lumber around to keep covered footprint down.  If that stuff can get in and out on rollers to be accessed by skid steer outside instead of inside, the roof footprint and price goes way down.
 
Otherwise, how tight do you plan to keep the building?  A rain and wind shelter (think carport with one or two sides) is a lot different to plan for than an enclosed, insulated, workshop.

[barbender]

I've seen pictures of saw sheds on here that had a vented peak, to let exhaust out  I have no idea how effective it was.

[doc henderson]

Barbender I think that would work.  I would use power vent and not depend on draft.  hot air will also go out.  just being out of the wind can sure help.

[Hackeldam Wood Products]

you can not run engines in a enclosed space. you will be sick or worse in no time from c. o. poisoning. 
not to mention the long term effects of all the other pollutants in engine exhaust. 

the only way to have a heated shop with that equipment is too use electric. 

[Ianab]

Run a large diesel gen set outside, and use that to power an electric mill. MUCH safer. Unless you have a way of extracting ALL the exhaust fume, like a flex hose from the exhaust to outside, the CO in the exhaust will get ya.

[Randy88]

My first thoughts were to build a 45 foot wide by 40 foot long machine shed, basically its what fits in the one spot I'd like to put it, open bay doors on one end as needed, when not sawing, fit trucks inside, which I also need.    Have doors that slid open on other three sides as needed, fit the mill against the back wall and edger along side wall, so nothing would need to be moved as trucks were put inside when not sawing, skid steer would also fit along with some misc stuff.    

Then I thought about a full ridge vent, not sure how effective if any it would be for fumes though.  

Then we discussed putting a large fan on one end in the rafters to suck air out and exhaust it out of the building, much like an livestock building.   

We've discussed heat exchangers, those are not that hard to build and are effective for removing moist air, not sure about CO2 though, didn't really find any info on that really. 

We've thought about three phase generator and run a pto unit off a tractor outside the building, but when the costs were figured up, it got really expensive fast, I'd want at least a 20 plus hp electric motor on the band, then a 5 hp motor on the hydraulics for the mill, then another 20 hp motor on the edger, plus to wire everything up.    A friend of mine is an electrician and even if we could find used stuff its not cheap.   The other issue is, we still do move the mill to other locations to saw sometimes, using electric motors really hampers that idea a lot.     

As for heating, no in floor heat, we were thinking a forced air heat exchanger off the OWB sitting right behind the shed so when we are not sawing, I didn't need to heat it.

We've looked at the idea of venting each exhaust pipe out of the building, but not sure how effective it is when running a skid steer or saws.  They are far from perfect when a machine is stationary, let alone moving constantly like a band sawmill head does.  

We've talked log decks to bring the logs in but when we drew everything up, that changed everything around so much, it somewhat was impossible to do given the buildings location to my furnace and other buildings keeping the prevailing winds in mind, the last thing I wanted was to put the log deck and my mill where sawdust was constantly blowing in my face if any of the doors were open in the summer or we had to constantly open a door to bring logs in on the prevailing wind side of the building.   To do that canned the whole building idea completely.

I know CO2 is a killer and dangerous, hence the reason I asked this question, its never been discussed much and by looking at others sheds, most saw in much better weather than I do and everything can more opened up and aired out, I can tell that by the saw shed designs and layouts.    

I've been to a few mills that had the edger and mill walled off in one portion of the building and the boards went through vinyl hanging strips to a lumber handing section that was heated and more closed up.    The edger and mill portion with engines on them were in a more open or ventilated section so to speak and they used electric forklifts to handle lumber and edgings.      Heat was blown into the more open end to keep the operators somewhat warm in frigid weather and in the summer, all the doors were opened up for cross ventilation. 

In the summer its not going to be an issue, only in cold weather or don't any of you saw when it gets cold out?

[beav]

How bout if you used propane fueled engines on everything?

[doc henderson]

hey randy, the CO or carbon monoxide is the big killer in exhaust.  CO2 or carbon dioxide is what we exhale and O2  or oxygen is what we need.  Just to be clear.  I agree with all that this is a risky proposition but i figure many on this site take a few risks and do ok cause they know what they are doing.  I found 25 feet of 2.25 inch flexible steel pipe for 60 bucks on amazon.  It could be done but yes you would need a suspension rig to follow the saw head.  Again this has to be a meticulous monitored cautious situation, and I only comment to try to help you be safe, esp. if you are going to do it anyway.  i added extra pipe to my log splitter to make it quieter so we can easily speak over the engine sound.  This really helps if you have an indoor air compressor as well to relocate the intake outside or in the attic.  most of the noise resonates from the intake.  I think if it is a drafty farm shed you would do well if you have good ventilation maybe just out of the wind.   radiant heat at the operator station.  CO only rises while warm then mixes into the air and is throughout the building.  so venting the roof line only helps if it ventilates the whole building.

[doc henderson]

propane would still produce CO.  some boilers are becoming very efficient and do not put out as much CO.  the vent-less propane heaters, I believe, are very complete burning and therefore low CO producing.   Remember, I have seen deaths from combustion engines inside of buildings.  I would still pipe the exhaust out of the building, and it may really cut down on the noise as well.

[TKehl]

In the summer its not going to be an issue, only in cold weather or don't any of you saw when it gets cold out?

I'm trying to, but have no roof at all right now.  A carport with one wall would be an improvement for me.   :(  :D

[barbender]

If you have a diesel engine, it will burn your eyes and drive you out before the CO ever gets to you😊 If you do more than set up a building that is more than a wind break basically, you're going to get in trouble.

[muggs]

How many amps of power do you have at your service?

[Hilltop366]

It might get tricky to get good quality air in an enclosed building with gas engines, it is my understanding that co2 is heavy and will be at the floor level and build up from there so venting through the roof may not get the best results for co2.

Moving the engines outside would be the best answer, not too hard for the hydraulic pump perhaps doable for an edger tougher with a band sawmill.

Another option could be a remote hyd pump and a hyd motor on the mill?

http://forestryforum.com/board/index.php?topic=103382.0;all

[Percy]

I've done a lot of reading here and elsewhere about sawmill sheds, but hardly any of them discuss exhaust fumes and how they address this in their shed design.      

So for the people that saw in cold weather and want the shed to keep the wind and cold out, so its somewhat warm, how do you handle the exhaust fumes?

I know its been stated a few times, a couple keep fans running year round, most never state how they exhaust the fumes.    

We run a small dust collection system in the house basement and was wondering if I'd hook up a dust system for the mill and edger, if it were large enough, does this suck some, most or none of the exhaust out along with the dust?

I don't have three phase power, so using electric motors is not an option, been to a few that use only motors along with dust collection and its very nice.  

I've been doing a lot of research on the perfect sawmill shed, but got to thinking before doing something, I'd better address exhaust fumes first.   The way it is now, I'd be running three gas engines, two for the mill, one on the edger, not to mention a diesel skid steer to bring logs and shuffle edgings and lumber around and chainsaws doing trimming and edging cutup as we saw.  

I'm a poor weather sawyer, meaning when its raining, snowing, cold and miserable outside and I can't do anything constructive, we saw lumber, right now we do it inside a machine shed, but its a process to get setup and take back down to cram equipment back in, part is done inside the rest outside and can only do it with doors fully open.      What I'm wanting is to have a shed, more dedicated so to speak, with plenty of doors and access so as the wind changes we can open and close doors and do everything under a roof and when its frigid out, close everything up and keep sawing, so that's the major concern I have is when things are closed up??     Any help or suggestions would be appreciated, thanks

Im a ways north of you(54th parellel)and I just live with it. I have a very large roof,,40 feet x 100 feet. I had planned on closing most of it and converting everything to electric...the WCB(workers compensation board) which is  the British Columbian version of the U.S.'s Occupational Health and Safety...says that dust explosion hazards are a big deal and I would have to clean rafters and electrical boxes and....the list was very extensive and expensive...An open sided building such as mine would not have to adhere to those regs....I went that way......gets pretty cold sometimes......then I go home and watch JUdge Judy.... :D :D

[Randy88]

I typed something up, but don't know where it went after I pushed POST??

Anyway, its a machine shed not a shop or house, so its not air tight by any means.   

Next I have 200 amp single phase 220 power is all.   

The edger is stationary, so to exhaust it out is no big deal.   

For the dust collector blower setup, can't a person hook the mill engines exhaust to that just ahead of the sawdust coming off the blade and use the blower to suck out the carbon monoxide with that??

Aren't CFM's of air movement the same for a blower as they are for a fan??

I still have to have as much or more incoming air that I have with the blower sucking or it won't work or its effectiveness will be reduced, right??

My thinking is, if I got an oversized blower setup and hooked it to a tractor pto which is outside the building, wouldn't the fumes be sucked out with the sawdust or am I thinking wrong on this and if so explain what I don't understand??

[Southside]

Mixing your sawdust and engine exhaust stream in the same collection system is a recipe for disaster.  If you have ever watched one of these saws at dusk you will see plenty of sparks coming off of the band and nice glowing embers on the mufflers, mix that with some dry dust (wood flour) that found a nook to hide in, plenty of forced air, and you have a really efficient way to create a blow torch that will burn green sawdust in the same way a bio-mass boiler works.  

My wife works in the safety and health along with Industrial hygiene field for the DOD, she deals with folks like Boeing, Tesla, NASA, etc.  With the exception of propane fork trucks, which have their own set of rules and maintenance / testing requirements they do not run engines in areas where folks work unless it is a permitted facility with specifically designed collection systems and for system test purposes only.  On top of that there are monitoring requirements and a slew of other regulations to prevent employees from being injured or killed.  

There is no good way to routinely run a diesel or gas engine in an enclosed or even partially enclosed building, add on the fact the head is moving back and forth and your collection system will not be effective at removing exhaust gasses.  Just to balance the system you will need to draft in the same amount of air that you are removing, so you will actually be introducing a bunch of cold air into your space by using an extractor for the exhaust.   

Can you build a drape curtain system like those used in dairy barns to break the prevailing winds?  One on each side and you would only have to close the ones that were a problem on any given day.   

[barbender]

Not to mention, you can see when your system is leaking sawdust. Not so much with CO👎

[Randy88]

Southside, with any curtain system, your still in an enclosed space, not air tight by any means, but still, how do know figure air movement and what is safe enough?? 

I just bought an edger from a mill that had the curtain system on the log deck, the edger and mill were in one room, basically a machine shed with one hole in the wall the log deck came through that had hanging vinyl curtains to keep the wind out and the rest was closed up, when I asked them about it, they told me they mill 1.2 million feet per year and have for years and nobody had ever asked before, and none of them had ever died or gotten sick, he also went on to tell that their blower was so large, it sucked air in through the curtains and since there was never any smoke from their diesel on the mill, they figured the gas engine on the edger they were using was a non issue, that and the engine was mounted near the suction of the blower and the exhaust blew at the collection port they figured it was good enough.     They also ran honda gas engines on their hand fork lifts moving lumber around.  I'm not sure I'd get by or attempt what they were doing, but since they'd done it that way for decades, can't say they were wrong either, but then I wasn't planning on applying for a job there or ever working in or around the setup ever either.

Others have stated diesel's are safer, basically they smoke you out long before your overcome with carbon monoxide, how does one calculate for good enough air flow using a diesel.   I've been to a few mills with the curtain systems and diesels on the mill and when I asked about air quality I just got a strange look was about it.

More questions on bust blowers, I've seen the sparks coming off band blades as well, how come there are no dust explosions??    There are in grain elevators all the time, even with dust blowers in use some have issues, also I've been told when a blower goes bad, like anything mechanical, it gives off sparks, does the blower itself spew sparks into the sawdust pile, or with enough air movement is it a non issue??    Basically how worried should someone be about a fire later on in the sawdust pile out back or is that something nobody really talks about but does happen?

Air quality is a huge deal to me, I've got lung issues the way it is, have for decades I'm trying to eliminate dust along with fumes of any sort either by design or by air flow.    Again, its a sawmill/machine shed of some sort, not an air tight heated insulated shop we're discussing.

[Southside]

With the curtains I was suggesting only lowering one or two at a time to block the prevailing wind so you still have an open, yet flexible, building. 

Dust explosions are actually not uncommon in facilities that produce wood pellets and I have personally seen the results of two. Also have seen three dust fires at shavings plants, particle size and moisture content play a vital role in it happening. Not as likely with a mill sawing green logs,  but if you don't run it all the time and settled dust gets a chance to dry just right when the heat source shows up you will have the same result. 

[TKehl]

Was hoping to hear the easy solution on this thread, but I guess this is a tough egg to crack for more than just me.  ;)

Thinking on it, the only indoor (with walls, not just roof) sawmills I've seen run with an engine have been the old circle mills with the exhaust piped through the roof.  So the engine is stationary.

The moving sawhead engine is the biggest problem.  However, if one could cool the exhaust down enough (expansion chamber maybe) tent it could go through a flexible tubing, like a high temp. silicone tubing, with the tubing running in cable track to avoid kinking...  Something I've thought about but haven't actually tried.   :-\

[doc henderson]

I think it could be done with an overhead arm with a pivot or a track.  I assume the indoors would be for the worst weather and the rest of the time the doors could be wide open. The pipe that is flexible is available for 60 bucks for 25 feet via summit racing. You could use solid tubing for parts that do not need to flex.  you will need to check the system frequently for cracks or degrade.  Even storing inside and operating with doors wide open in bad weather would provide some benefit. My disclaimer is I assume I am commenting to "grown ups"  who do not want to die and that have some mechanical ability and common sense.  At the beginning of the thread is sounded like this was a stop gap so a person could do their day job and still mill on a limited time schedule and mill no matter what the weather.  all that being said I think there are some options but all come with some risk and must be tested and monitored.  I am glad to hear it is not an air tight building.  I mill outside and if the weather is bad,it does not bother my income.  The pivot arm I am thinking is like a car wash that helps the wand hose follow you.  I would not combine your dust and exhaust for many reasons, but if it gets plugged you are creating a life threatening condition.  I am assuming you do not have 5 employee that would work in these conditions and be subject to OSHA ect., I assume you are an independent self employed guy trying to plan for bad weather so you can support your family come rain or shine,  Be care full what ever you decide.  Cause if you are dead, it will also deprive your family of you!  It had been a fun topic even if you never use the info.