Height for ventilation hood?

[Cosmo]

Okay, we have decided to build a hood that covers our entire table (12 torches) in our studio. Now, some people like to work standing up, and some like to work sitting down. So, in order for people to stand, the hood needs to be higher than it would if people were sitting. I know fumes rise, but does it matter how high the hood is? We were thinking about 7' off the floor, which would allow really tall people to stand without the hood interfering. That would be about 4' above the table. Is that too much distance?

[MikeAurelius]

It should be fine, but you have to be sure you have enough "face velocity" to draw the fumes up -- I strongly recommend 125 CFM per square foot of "face" for overhead vents. 100 CFM just plain 'does not cut it' and fumes will drop and not be removed, especially on vent hoods that are higher, like yours.

[Cosmo]

Well, if I did my calculations correctly, we should have close to 200cfm per square foot. It's good to have friends in the HVAC industry...

[e. mort]

Have you considered just raising the height of your table? Then people who like to sit could sit on tall stools, and people who like to stand would still have the bench at the proper height? I am currently deciding how high to build my own table for this reason, but I am still working on figuring out the optimum height.

Eric

[MikeAurelius]

Ok - but be careful with pulling TOO much air - it all has to be replaced, and this is winter...brrrrrrr

It's currently -2 F outside and I'll be damned if I'm going to turn on the ventilation system today - I'm going Christmas shopping instead.

Instead of raising the height of the table (with legs), consider a "table insert" that can be screwed down with deck screws for those who work standing up, then removed if someone wants to sit down. The space underneath can be used for tool/glass storage.

[Cosmo]

Yeah, our table is not going to be able to be raised and lowered easily. We have it designed so that there is a "trap door" in the center with a metal trash can under it. At the end of classes, we are just going to open the door, sweep all the trash through the hole and into the trash can.

We have our hood designed so that there are two openings inside it with two separate fans. That way we can run one if we only have a few people working, and run them both with a full class. Hopefully it will work out okay. Of course, we are still planning, so things may change before we get open.

[PaulaD]

Chad love the trash can idea!!
Paula

[Cosmo]

Chad love the trash can idea!!
Paula

Thanks. I wish I could take credit for it. I saw something similar on the Food Network where they designed a new kitchen with a built in cutting board. It had a hole in the middle with a trash can below. A light bulb went off and I had to go get some paper and sketch it out...

[PaulaD]

Ahhh. I don't look at kitchens!! Heh. Heh. Paula

[Cosmo]

Unfortunately, I look at them WAY too much. And my waistline hates me for it...

[PaulaD]

I don't have a waistline....
Paula