Welder Evac System

[DaveHess]

Has anyone ever fabricated a home-made fume evacuation system for use when welding? I checked out Lincoln units but there is no way I can afford to spend over $1000. I was thinking of a squirrel cage and tubing to run outside of the garage but I need this to be effective since I will be closed in for awhile (North Dakota winters-Brrrrrrrr). If someone has and they don't mind, can you post how you did it, parts used, and maybe some pictures. Thanks in advance.



Dave

 

[kenny61]

I'll only suggest this since no one else chimed in. How about a wet dry vac with the exhaust piped out side. kinda like what they do with wood shop equipment. I would just keep it far enough away so that you aren't sucking up the flying sparks

 

[opjohnny]

I think it is a very good idea. Depending on the size of the shop and how often the exhaust is on and its size you may have to provide make up air(fresh air). Your on the right track by keeping the fan motor out of the exhaust air stream. If the shop is air tight you will start to pull a vacuum and wont be able to move much exhaust air with out makeup air.



John

 

[DaveHess]

Kenny61: I had entertained the shop-vac thought. My idea was to take an outdoors dryer vent, like on the back of a house minus the flapper door, hook it to my shop-vac by reducing the 3 or 4" opening of the hose end of the vent to the 2. 5" of the vac, and suspend the vent over my work piece. My thoughts were to clean the vac out and remove the filter element so the air could move freely through the vac. The next dilemna was how to attach the exhaust hose to my vac. I'll have to kick that around some more.



John: The garage is 1098 sf and insulated, drywalled and heated. You guys just gave me another idea for venting the garage to the outside. For some reason I hadn't thought of installing another dryer vent to the outside of the garage as the exit point for the fumes. That would eliminate the garage door having to be open for a hose to run underneath and I could cap the inside connection when not in use.



Keep the ideas coming guys!!!!



Dave

 

[kenny61]

I have a craftsman shop vac the motor detaches so you can use it as a leaf blower the exhaust is used by putting in a plastic pipe attachment I'm sure a piece of pvc could be made to fit into it. Since your on a budget if your shop vac wont work how about suspending one of these 12 Amp Leafhog Blower Vacuum LH5000 over your work and piping the exhaust out side. I think it would clear most the smoke and not creat a vacum in the garage. the nice thing about the shop vac idea is that, oh heres another idea put the shop vac outside and you dont need to run an exhaust and it will keep the noise outside too

 

[kenny61]

You could probably also use a high cfm bathroom exhaust vent fan piped outside. Broan L500 - High Capacity Fans - WAMHomeCenter.com remember your imagination is only limited by your budget

 

[DaveHess]

You could probably also use a high cfm bathroom exhaust vent fan piped outside. Broan L500 - High Capacity Fans - WAMHomeCenter.com remember your imagination is only limited by your budget

OH! I like this one and I work part-time at Lowes!!! Maybe I can fashion the system to be expandable. My garage is in an "L" shape with the bottom of "L" being the shop (44' Deep). I sometimes like to wheel the table out to the middle of the garage where I have more room. The garage dimensions are 36' wide by 26' deep except for the third bay that is 44' deep. But I digress. I am going to explore the bathroom vent idea. That would also work great for venting excess fumes no matter what I am doing in there. As for the vacuum, I have two windows I could open partially to bring in fresh air. The wheels are turning... ... Kenny61: What PD are you with???

 

[kenny61]

You could get 3 bathroom fans and make an L with the duct use a y on the last 2 fans to tie them into the L. I wouldn't use them for any fumes as they are not explosion proof rated and flammable fumes in the right concentration would make for a real nice show. Sorry I don't give out where I work over the internet too many weirdos out there. . (you not included)

 

[DaveHess]

Kenny61: You know what? Being a retired Fed Agent (AFOSI) I should have thought of that. You are right and my bad! Thanks for the continued input. I understand on the whole explosion bit. Considering the bedrooms are above the garage, I am thinking CinCHome would not be very appreciative of my efforts if I performed an ops check on the house smoke alarms.

 

[kenny61]

No problem. I know most people are aware of fumes and so such but from my years of dealing with the public and reading news of the weird I just like to give my little disclaimer

 

[DaveHess]

Understood. I thought pretty hard about even putting my location on these threads. BTW, I am originally from Orchard Park, NY (12 miles S of Buffalo). USAF retirement dropped me here in ND.

 

[GHarman]

Been watching this since it opened. I have a shop that needs a vent system, also. I have worked as a weldor for many years, and the one thing you need to do is get rid of those fumes. Explosive concentrations are not an issue unless you are venting your acetylene tank into your exhaust system:-laf. Not a good idea! You can move alot of air or a little, speaking in volume of air, but it has to be just right or the system will not be effective. A spark arrest system should be considered for fire prevention and can be incorporporated into your welding bench. Instead of a whole shop vent system, why not a down draft welding bench. I have used "elephant trunks" and overhead vents in an industrial environment as well as water tables for cutting(very good, BTW)with a plasma and oxy-fuel. Their drawback is the mess to clean up. High velocity air movement is necessary for any system to work efficiently. A shop vac may be a consideration on a tight access, however, the more air you can move the better it will work. As it has been mentioned, if you are discharging to the outside of a closed shop, you will need make-up air. An air to air heat exchanger may reduce the temperature drop on the coldest of days. Just some thoughts. Be careful, out there, my L. E. Friends! Semper Fi! GregH

 

[RABruce]

Been watching this since it opened. I have a shop that needs a vent system, also. I have worked as a weldor for many years, and the one thing you need to do is get rid of those fumes. Explosive concentrations are not an issue unless you are venting your acetylene tank into your exhaust system:-laf. Not a good idea! You can move alot of air or a little, speaking in volume of air, but it has to be just right or the system will not be effective. A spark arrest system should be considered for fire prevention and can be incorporporated into your welding bench. Instead of a whole shop vent system, why not a down draft welding bench. I have used "elephant trunks" and overhead vents in an industrial environment as well as water tables for cutting(very good, BTW)with a plasma and oxy-fuel. Their drawback is the mess to clean up. High velocity air movement is necessary for any system to work efficiently. A shop vac may be a consideration on a tight access, however, the more air you can move the better it will work. As it has been mentioned, if you are discharging to the outside of a closed shop, you will need make-up air. An air to air heat exchanger may reduce the temperature drop on the coldest of days. Just some thoughts. Be careful, out there, my L. E. Friends! Semper Fi! GregH

Maybe I'll chime in for a sec and offer my . 02.

I have tested many fume exhaust systems over the years in my job as a certified HVAC TAB technician, and feel that you might be a bit short (maybe quite a bit) using the bathroom fans etc. Nearly all of those have plastic impellers, and if you are going to do continuous welding, the ductwork will get hot.

Most systems are designed for each node to move around 450 cfm against a static pressure of 2 - 2. 5 in. wc if you are using a side draw inlet. The ductwork on the drop should be 8 inch. If the Engineer has designed the drops with 6 inch ductwork, I usually have a devil of a time trying to get them to draw properly. I suspect that 4 inch dryer vent might be less than satisfactory, but it might just be enough to keep a casual user from gagging all the time. Your dough.

You could go to less air volume if you have a capture hood above the work piece, as the hot gasses travel straight up, and are more easily captured than with the side draw slot types.

I have never yet seen a system that has the motor in the air stream, and I just wouldn't do it from a safety standpoint.

Again, just my . 02.

 

[GHarman]

Maybe I'll chime in for a sec and offer my . 02.

I have tested many fume exhaust systems over the years in my job as a certified HVAC TAB technician, and feel that you might be a bit short (maybe quite a bit) using the bathroom fans etc. Nearly all of those have plastic impellers, and if you are going to do continuous welding, the ductwork will get hot.

Most systems are designed for each node to move around 450 cfm against a static pressure of 2 - 2. 5 in. wc if you are using a side draw inlet. The ductwork on the drop should be 8 inch. If the Engineer has designed the drops with 6 inch ductwork, I usually have a devil of a time trying to get them to draw properly. I suspect that 4 inch dryer vent might be less than satisfactory, but it might just be enough to keep a casual user from gagging all the time. Your dough.

You could go to less air volume if you have a capture hood above the work piece, as the hot gasses travel straight up, and are more easily captured than with the side draw slot types.

I have never yet seen a system that has the motor in the air stream, and I just wouldn't do it from a safety standpoint.

Again, just my . 02.

You are right! Especially about the motor not being in the exhaust stream. Not necessarily from a fire prevention standpoint ( a valid consideration), but from a fan motor longevity standpoint. That exhaust that you are getting rid of contains corrosive fumes and fine particles of flux and other debris. If you use the direct vent with the elephant trunk and high velocity air removal, you will pick up everything! If the motor is in the stream and is not sealed, it will magnetically and electrostatically accumulate the trash that is in the exhaust stream. Our ductwork, in the shop where I taught, years ago, was full of welding debris. We had an electrostatic air filtering system. You still had to have the elephant trunk about 6" away from your work or it wouldn't draw the fumes. You need to be able to clean the system, periodically. Fumes do tend to go up, but a properly built down draft table does work, in a small shop, with a spark arrestor in the bottom of the funnel with a drip leg below it for cleanout. That does not address the jobs where you cant get them up on the table. Thats where a seperate hose would work for those "tight spaces", under a trailer, for instance. Just trying to think this through. Its cheaper to discuss possible issues than to correct hardware. GregH

 

[DaveHess]

Holy Cow! There have all kinds of issues raised here I did not even think about. As I read the above three posts, I start to see why the Lincoln system is $1000. It has the elephant trunk and has a self-contained air cleaning system on wheels. Things that make you go hmmmmmmmm.....