# Fan grill mounted directly to wooden shed?



## martymcfly (Aug 21, 2013)

My fumehood is now complete and uses 2 4" fans which i can vent out of my work shed. What im planning was just attaching the ducting directly to a fan grill and venting out the side of the shed.

Can anyone see any problems with this or is it a common method of venting? I was wondering if the wind could blow the Nox fumes back over the wooden shed and cause problems?

Another option would be to change from 4" to 2" rhone pipe and duct out and up over the shed maybe a foot or two higher than the roof itself.

Any criticism or suggestions welcome.


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## rickbb (Aug 21, 2013)

With 2 - 4" fans you don't want to constrict the flow down to a 2" pipe. I'd go for 6" PVC pipe instead and attach it to a plastic dryer wall vent to keep rain from getting in.


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## martymcfly (Aug 21, 2013)

rickbb said:


> With 2 - 4" fans you don't want to constrict the flow down to a 2" pipe. I'd go for 6" PVC pipe instead and attach it to a plastic dryer wall vent to keep rain from getting in.



I was planning just using plastic ducting but can easily get 6" ducting if that was the better choice. I was wondering if the 2" pipe would be too restrictive.

Do you think mounting the plastic vent to the wood would be fine and no reaction would happen with the shed itself? The only other thing i was worried about was the fumes coming back into the shed. This will be my first refine so im not quite sure how much nox fumes im going to be getting.


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## rickbb (Aug 21, 2013)

You would want to place the vent well away from any open windows or doors etc. That should prevent any returning fumes. 

How much fume you generate depends on the scale of your digesting and which process you use. 

I put the vent to my table top fume hood around the corner from the door, about 10 to 12 feet away in total and do not have a problem with fumes re-entering the shop. I have the plastic trap door type of dryer vent and the only thing I've noticed is there is a very slight staining to the paint under it and I've been using it for about 6 months now. I do try to hose it down every so often so there is no crud build up under the vent exit.


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## jeneje (Aug 24, 2013)

Something to think about here, venting any kind of NO gas outside is dangerous, not only to you but the environment too. trees, flowers, grass, birds will all die from this. A good scrubber setup will help control the fumes. There are several scrubber setups posted here on the forum.

Ken


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## rickbb (Aug 24, 2013)

True, a vaccum assited scubber on the reaction vessel is the best way to deal with noxious gasses. But the work area still needs to be vented safely with a fume hood.


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## Smack (Aug 24, 2013)

What's keeping the fumes from recirculating back through your shed and you?


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## rickbb (Aug 25, 2013)

Smack said:


> What's keeping the fumes from recirculating back through your shed and you?



Distance from any opening + dissipation into the atmosphere + small amount of noxious fumes to begin with.

Fume hoods should not be the primary means of dealing with concentrated fumes, but only as a means to provide the worker a safe breathable work space.


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## Smack (Aug 25, 2013)

That question was directed at the OP.


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## rickbb (Aug 25, 2013)

oh, sorry, my bad.


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