Is this setup safe for fuming? Pictures Attached

[PyroAaron]

Hi,
I would like to fume five pieces a day. I want to make sure I am safe so I don't kill myself. I am at the right torch. Our ventilation fans are 200 CMF each...400 total. I have a shield in front of me as well. I always wear a N100 respirator while fuming, but I take it off about two-three minutes after fuming to blow the tube. Unfortunately, I don't have a very good source for replacement air into the room. There is a door that enters the studio. I put small fan there to pull in some air, but not enough to disturb the flame. Should I put a larger fan there and aim it to the side of the studio? Is this enough to be safe?

The picture showing my shield didn't turn out as well as I hoped, so I outlined the shield.

SORRY ABOUT THE MESSY STUDIO :shock: !!!!!

[MikeAurelius]

NO.

Your ducting is very seriously bad. Each hood should be ducted outside by itself. Never double up ducting like this - you will back draft one hood or the other.

Additionally, unless the the hoods are only 1.6 square feet, the air flow of 200 CFM is way under what it should be. Each hood should be running about 125 CFM per square foot of coverage area, minimum. Higher, closer to 200 CFM per square foot if you are fuming.

[MikeAurelius]

Also, if you have a "bad source of fresh air", you will need to fix that, pronto.

You need to be providing the exact same amount of fresh air as that you are exhausting, in a free flow manner. It should be in the form of a duct, but you can use an open window or door to the outside, provided it is at least 10 linear feet from the exhaust ducts.

[Anakin's Glass Eye]

I have to agree with Mike. You need a lot more air flow, especially if you are fuming.

If I'm not mistaken, those are range hoods that you're using. I would try to retrofit fans that can push at least 600 cfm each. 800 or more cfm would be better though. And, they should each have their own duct to outside.

[PyroAaron]

Thank you for the replies! I can definitely see how backdrafting is a problem if only one fan is ran, but we always run both....is it still a problem? Any ideas of how I could soup this thing up on a low budget? I will be moving to Florida in August, so this will have to be a temporary fix.

[PyroAaron]

http://cgi.ebay.com/SQUIRREL-CAGE-BLOWER-FAN-FUMES-EXHAUST-1600-cfm_W0QQitemZ8276588043QQcategoryZ3101QQcmdZViewIt em

I just purchased this beast! 1600cfm should be enough. I'm planning on re-configuring the duct work and installing some sort of air replacement system. Is it okay to use the range hoods to collect the fumes or should I install more of a shell shaped unit?

Thanks!
Aaron

[Anakin's Glass Eye]

Aaron,

A range hood is a good start. I bought a commercial style hood on eBay that has two fans pulling 800 CFM total. I went to Home Depot and boucht a stainless steel range "backsplash" 36" x 30". I attached it to the hood and it provides a nice baffle to keep the fumes going up into the hood. IMO you need something at the back and maybe something on the sides to direct the flame exhaust. My plan was to add baffles at the sides but my setup is working nicely as is. I did a smoke test and my hood pulls air from 12" to either side of the hood. I think 1600 cfm will be plenty. There are some neato variable speed fan controllers on eBay you can get to controll the fan so you're not overpowering yourself.

Brad

[PyroAaron]

I'll have to do the smoke test once I get it hooked up. It has three speeds on it, so hopefully I can adjust it to my needs. I bet the rods will get sucked right off the table at 1600, lol :wave: !

[MikeAurelius]

Hey Aaron -- the only time you should run multiple hoods off one duct is when you have one fan (usually) outside.

I ran my first studio like yours and we had nothing but problems with backdrafting, even when all the hood fans in the line were running -- the problem is severalfold - but basically we were trying to push too much air through too small of ducting. Once I started researching the issues of moving air, I discovered what the problems were and what air moving professionals do to resolve issues like this.

If you have one (large) fan, mounted either inside or outside, but basically at the end of the duct run, you can run multiple hoods off of it, provided your ducting can handle the air flow. However, if you have multiple fans (one per hood), you must run one exhaust duct per hood outside. There's no real way around this, even if you use dampers in the ducting, there will still be 'blow back' and exhaust air will still circulate in the room -- air, like water will always follow the path of least resistance. And especially in a situation where you have very poor make up air, recirculation in a multiple fan/single duct environment is highly likely AND dangerous.

[boroburner]

Hello Mike,
Why the 10 linear feet from the exaust point?
B

[MikeAurelius]

National code - ensures proper dispursion of fumes and exhaust gasses so they aren't sucked back in to the building in their original concentration.

[boroburner]

I get it the exiting vent is suposed to be 10 feet ](*,) from the intake
I thought you had ment the in take had to be 10' from the hood.
Thx for making sense of that for me.
B

[PyroAaron]

Thanks again for all the help! I'll post a picture next week when it is all hooked up! I can't wait to see this sucker suck!