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Help to design ventilation


John88

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Hi,

I need your help. I am preparing my gas (propane, devil forge) forge in my garage (width : 3m, height: 2m45, length : 5m40 in metric system).

I put my forge between plasterboards (wall of 5cm width with ceramic wool). The left and right sides are 1m (width) x 2m (height) and the back wall is 0.65m x 2m.
The forge is located at 1m50 of height. So the problem is there are no ventilation but my "forge walls" are located in a corner of my garage.
The walls of my garage in this corner are the two faces (left side width: 3m, backside width : 5m40) linked to exterior.
The outside doors are not easy to open. So I can do it until I buy all elements of my air system but it is not ok on the long term.
 

I am worried about monoxide and I would like to design it properly to avoid intoxication and death. I read that air extractor and ventilation are mandatory but I also read that it is recommended to put an aspiration close to the forge. I also have other tools like backstand, grinder and saws.

Can you give me advises? How to size air system, where to put air elements?
Maybe some online international shop links?

Thanks!

fotge.png

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Alive is good. Forging dead is challenging, to say the least.

My immediate, non-specialist reaction is that putting an exhaust fan high up in the wall next to the forge and some kind of air intake lower down on the opposite end of the long outside wall would be a step in the right direction. The combination of hot air rising from the forge, carbon monoxide being slightly lighter than normal air, and colder air entering at some small distance will create a good flow of bad air out/good air in. I don't know how much volume you would need your fan to move, but I'm sure that other, more experienced folk may have suggestions (or indeed much better ideas).

Make sure to install carbon monoxide detectors, as well.

And welcome to IFI! We have a number of members in Belgium, so hopefully you'll be able to connect with them as well.

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Can you make the doors easier to open?  Perhaps make a good overhang to keep rain from coming in?  I always go by "Excessive ventilation for a gas forge is just barely enough!"  Though in my shop it's all passive so far. (10' walls, open gables and 10'x10' roll up doors on opposing ends.)

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But some people recommended me to force ventilation and told me that opening the doors is not enough.
Basically I wanted to put a stainless steel pipe of 15mm diameter above the forge.
And half-open the door when I forge but they discouraged me.

These people also told me that I have to take care of the dust due to the backstand and other tools :-/
I found on another forum (french forum) that they recommended this https://sysventilation.com/extracteur-centrifuge-torin-sv10-10-900-ddc-270-270-245w-debit-3250-m3-h.html but my setup is not the same.

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15mm is just over 1/2", that has to be a typo, 15mm pipe is appropriate for supplying water to a kitchen sink, NOT venting dangerous fumes oout of a room. 250mm would be a little more like it for a powered exhaust vent. Over a propane forge in a garage I'd use 300mm or larger. 

I prefer to place CO monitor/alarms about head high, that's where my nose and mouth are. If your garage is attached to the house you'll want CO monitors in the house, CO is insidious and gets everywhere.

I'm just a guy though, there are ventilation professional experts on Iforge I expect one to speak up soon, they are the folks to listen to. You'll also get a lot of folks without much knowledge or experience offering advice as well. I don't fault folks for wanting to be helpful but this is too serious to listen to folk who don't know what they're talking about.

I'm at best a little above a know nothing, I have some experience venting welding fumes and CO from my shop but I gladly defer my opinion to the real experts.

If adequate venting is a problem, I HIGHLY recommend John's suggestion of making your propane forge portable and moving it outside a man door to use as a good solution. It's easy and safe plus you can move it back indoors for safe keeping.

Frosty The Lucky.

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Hallo buurland genoot.

Since you have plasterboard all around your forge I take it it is closed from the back? 

The fan you posted is maybe a bit to much, your shop is only 40m3. That would mean the fan refreshes the air about 80 times each hour. Why not use a old extractor hood?

 

 

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Well I forgot the '0' 150mm :-)
But ok, I will wait professional expert. Thanks !

Yes, it is closed but I can open the back. My devil forge looks like this http://devil-forge.com/220-thickbox_default/dfprof2-2d.jpg. I filled out the back hole with ceramic fiber that I can remove.

 

About the extractor hood I have no idea how to size it. From forge website (angele-shop like) it is for coal.

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3 hours ago, John88 said:

But some people recommended me to force ventilation and told me that opening the doors is not enough.

I forge in a garage with the door open and have yet to have any CO problems, even without forced ventilation.

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I forge in a garage, but my forge is on the opposite side of the garage as the door, so I needed some way to capture heat/fumes and push them out. I bought a glass blower's ventilation hood from Griffin Glass along with a 1000cfm fan. The hood is just long enough to capture the fumes, but in retrospect, I wish I had gone with the larger hood, because the smaller hood won't capture it from both sides of the forge if the rear door is opened, so I have to move it outside if I'm going to open the back up. My goal was to run the forge with the garage door closed to damp noise down, but prevent heat build up on the ceiling and prevent CO issues.

At any rate, the fan is very loud, but it seems to suck out all the heat and fumes, because I've not measured any additional heat buildup on my ceilings or had any one of them 5 CO detectors go off or even register above 0. The catching point is that the fan is only rated to 140f. The issue being that the motor is inline with the air stream. I figured worst case, if it dies, I can use the chassis and blade to make something with an out of band motor, but it hasn't been an issue yet. The 12 inch intake sucks in a lot of other cooler air and the temp in the duct never gets above 80, even when ambient temps are high. You can feel the heat going in, but it's barely a small portion of the air the fan is sucking in, it gets a lot of ambient air. If you let too much heat build up on the hood, without the fan running, it may have a different outcome, so I usually start it up a few minutes after my forge. The fan blows the fumes out the window, I have it hanging just in front of the opening, but you can also attach a 10 inch duct to the opposite side of the fan and vent it wherever you want (out a wall, for instance).

I also use two window fans, which I can adjust to exhaust or bring in air, to bring in fresh air to the garage. I've worked with it all running 5-6 hours and it's never gotten overly hot on the ceiling or had any CO levels register on the monitors. The small or large hood will depend on your forge, keeping in mind heat doesn't rise directly above the forge, it usually seems to spit it out a foot or two in front and (if it opens) back. I have the hood positioned about 4ft above the forge, so the air has some time to cool, I think the hottest I measured it above the forge at that height was around 120-140f. I think the lower you have it, the hotter it'll get, but the more likely you are to capture all of the fumes with a smaller hood. 

I also looked at range hoods, but they all had to be cut into the ceiling with a vent. I think having something like that may be preferable if that's feasible for your application, but if you can vent straight up, I'd assume a fan wouldn't necessarily be required for exhaust, just for bringing air in. There are plenty of examples of this for coal forges, you could probably get away with the same thing provided the duct is large enough and the hood was positioned low enough. I haven't tried, though I may when I move to a dedicated shop in the future.

Also be mindful of the fire risk. I have a door opener next to my garage door in case I need to get it open. If your doors are hard to open, I would address that also, because if you get trapped and have a hard time opening them, that isn't ideal. I also keep 4 large fire extinguishers around the garage and a bucket of sand I can use to smother small fires. 

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9 minutes ago, ThomasPowers said:

Adodero, could you just use a snug vent pipe over your forge's rear door going straight out the side wall?  Generally you don't need access on the back, just the ability to push a length in that direction to heat the middle.

That's something I hadn't considered, I'll look into that. Thanks. 

I had considered extending the hood itself, but it would be a lot of work and I am not sure it's something I wanted to mess with. 

My current setup is somewhat temporary, as I'm waiting on my Chile forge to be completed and sent out in the next week or two. After that, I plan on creating a more permanent setup for that forge, where my current forge will remain a bit more portable, as it's easier to move around and is more versatile due to it's smaller size. 

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I have my gas forge mounted to a slightly modified gas grill cart: Tossed the grill body and bolted a piece of sheet steel over the gap and then mounted the forge on top the sheet.  Over the last decade I have gradually modified the cart: installed sold rubber ball bearing wheels on a retrofitted steel axle, added cross bracing. it's about time to do something with the wooden slats on the handles:  Perhaps an expanded metal tray for cooling tools...

Easy to "cart" around; I've even rolled it up a couple 2x12's into the back of my pickup to take it to a demo.

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