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I Forge Iron

Draft not strong enough?


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First of all, sorry for the poor english, I'm not familliar with all the correct words (yet ;-) )

 

Proud to have my smithy in my shed!  But it's in a 'closed' environment.  (See picture)

I have a hood and a smoke extractor that is not v powerful.

 

Anyway:  I've been smithing in there for a while now, and I get the feeling the draft is not strong enough:

No smoke in my shed, but I tend to get a dry throat and sometimes a slight headache after a few hours of forging.

 

I was thinking maybe it's from the gasses released from the coals?  So I'm thinking about getting a more powerful engine for the suction system.

 

I found this one on the internet from a guy that lives closeby:

http://www.2dehands.be/bouw/gereedschap-machines/aambeeld/rookafzuiging-uit-smederij-199306558.html

 

He says it was used as a powerful smoke exhaust system in an old smithy.  But I have a hard time imaging how a fan like that is used for a smoke extraction...

Looks like a blower to me...

 

Anyone have any clue how that smoke extraction system the guy is selling should work?

Anyone have any other ideas to solve my problem?

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Hi Elmarg!

 

I found this:

http://www.directindustry.com/prod/delta-neu/centrifugal-type-fans-16555-462473.html#product-item_36829

 

It looks like a pretty strong exhaust fan to me. The minimum capacity is 0,66 m3/s which is good enough to suck out all the air from a small shop under a minute. If you buy it maybe you ought to get an other fan to put some air into the shop as well - so the air can flow through the shop.

This snail like construct is a quite general among the fans.

 

About your problem: CO (carbon monoxide) poisoning - as much as I know - starts with headache, dizziness, nausea. Low concentration in air can cause no harm in short time but can be deadly in long (3hours).  And it is not a joke as it kills very effectively.

Increasing CO2 (carbon dioxide) level is even more dangerous as if it is high enough to get inhaled it can cause faint in 2-3 inhalation. As one hits the ground they become surrounded by CO2 and then death is almost certain.

 

Although I have to ask: do you drink enough water while smithing? Even in a well ventillated shop dry throat and headache can occur in a couple hours of hard work if there is no hydration. 

 

And one more thought: have you checked what happens when you put input airflow to the shop? A simple household fan can work and make your smoke extraction more effective.

 

That's all I have. 

Congratulation on your blacksmith shop! I wish you good and fruitful times in there!

 

Greetings

 

Gergely

 

 

 

PS: there are pretty cool things on that auction site you linked in. That whole smithy for example...  ;)

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Hey Gergerly,

 

Thanks for the tip!  I'll definitly try to add some input airflow! Haven't tried that yet.

 

I don't really drink enough either :p you know how it goes... I forget the water bottle, then I'm too busy to be bothered with drinking... Maybe the problem is just dehydration... 

But It doesn't feel like the dehydration type of headache to me...

 

Maybe I formulated my question about the fan a bit odd... what I mean is: I don't see how it fits into the chimney? the one I have now has an in and an out and a little thing to catch ashes, so It just fits between my hood and the chimney, but I don't see how this new one works, it doesn't fit in between 2 chimney pipes like the old one does in my eyes, or am I missing something?

 

BTW: I emailed the guy selling the whole smithy, but he doesn't sell gear seperatly and I don't have that kind of budget atm :(

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Look into building a side draft chimney.  The method you are using is very inefficient as 90% of the air being exhausted is just room air and the smoke almost has to "luck" into going up the chimney.  Also what is the diameter of your chimney?  Forge chimney's tend to be larger than wood stove chimneys.

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OK, I see now (I hope). Look the pictures on the seller's ad, if you look at the second one from the left you can see two attachment holes (my words, sorry). The upside hole is obvious you see it in all picts. On the left side on the other hand there is an other hole. You attach the pipings to these holes. So you need to install it differently as yours is now. It needs a 90" angle turn in the piping.

 

 

I don't really drink enough either :P you know how it goes... I forget the water bottle, then I'm too busy to be bothered with drinking... Maybe the problem is just dehydration... 

But It doesn't feel like the dehydration type of headache to me...

 

Hehe, I know what you're talkin about... And I often had those headache-like feelings back when my chimney was smaller diameter. Now there is no smoke nor headaches.

 

BTW: I emailed the guy selling the whole smithy, but he doesn't sell gear seperatly and I don't have that kind of budget atm :(

 

Yeah, I feel for you...

 

Greetings

 

Gergely

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Look into building a side draft chimney.  The method you are using is very inefficient as 90% of the air being exhausted is just room air and the smoke almost has to "luck" into going up the chimney.  Also what is the diameter of your chimney?  Forge chimney's tend to be larger than wood stove chimneys.

 

Yes, I've also been thinking about just getting rid of that hood and put up a side draft chimney.

Could you link me some info?  As in, how close does it have to be to the fire? Does it have to go straight up or is it allowed to travel a bit horizontally before going vertically?  I would prefer not to go straight through the roof but rather through the back wall you can see in the picture at post 1, then straight up.  Just a matter of amount of work... don't feel like waterproofing the roof again...

 

Chimney is about 12 cm I think, same diameter as the smoke extractor exit.

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Hi again!

 

I'm really not sure about these things but I just have to put them into words. So please read it as only starting a conversation:

 

As I think the diameter of the chimney/flue only matters when there is natural stack effect. But in this case a motoric exhaust fan produces the move of the air. So the 12 cm dia is as good as any bigger if the capacity of the fan is enough to move out air from the shop. I think there can be two major problems: on the one hand the capacity of the fan is too low, or on the other hand the airflow is somehow blocked or partially obstructed.

The second one can be cured with an other fan indicating airflow input to the shop. And - that's why I bother you guys with all of this - in that case the whole problem is solved with a simple fan added to the shop. No big changes, no big costs... just continue the real work.

If the motor is too small then there is a chance that the Cobra exhaust fan will help, because it is quite powerful. But you will need the input fan even more because it will generate a bigger need of incoming air.

 

All right, that's it. I just can hope this all makes sense and is understandable by others outside my head.  :) (The others inside my head say they understand it, bruhaha.... :D )

 

Greetings

 

Gergely

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  • 3 weeks later...

That's what I was thinking too gergerly.

 

Either way, I've left the door open a bit last week and it seemed way better, so for now I think I'm just gonna make sure I have enough IN airflow for now with a small vent (so I can close the door and the neighbours don't complain about the noise)

 

Thanks for all the advise guys!

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I also have to keep the doors closed for noise when forging.

 

I use positive pressure ventilation in my forge.  A cheapish Ø500mm (20") industrial extractor fan blowing fresh air into the shop. This does two things:- it is the fastest way to get rid of fumes and get fresh air into a space, much more efficient than extracting, so it is advantageous for welding fumes, paint fumes as well as fumes from the fire; secondly it pushes the noxious air out through any available gap, your horizontal flue being the gap of least resistance so it will assist the hearth fumes to get out. :)

 

I had a problem with heat and fumes in my previous shop and hinged some flaps off the bottom of my smoke hood to reduce the gap between hood and hearth. It helped, but if you are going to do any metalwork a side draft seems the most versatile system.

 

Alan

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