Ventilation better UP or DOWN?

[Seasoned Soul]

I replied with this question in another thread but no one responded, well not yet anyway..LOL, so I decided to throw it out for the multitudes. I'm at this crossroad. I viewed a studio which had their vent work going down and out, looked nice. I wondered why I haven't seen more of this. It seems a better use of space with all the duct work going down and in front of your leg area then going up behind your play area. Is one better than the other?

[Dale M.]

UP is preferred because hot tend gasses rise (convection)........

To go down you have to increase velocity of air flow to suck down gasses which have natural tenancy to rise..... With increases air flow it tends to suck flame in direction of air flow in a unnatural way this cause flame variation that may be adverse to controlling the heat of glass in flame....

Its about the same concept as pushing on a rope to get it to move or trying to get water to flow up hill.........

Dale

[pinkcb]

That makes sense to me...So a supplemental question then becomes what is the optimal height above the flame? I've seen pictures of people with their venting right up to the ceiling and out and if I don't have to go that high I won't.

[Dale M.]

Its all about capturing the gas plume off flame....... To bad there is not some really concise pictures of plume shape and effect hood and air flow has on plume....

Unfortunately I do not have access to multiple torches or the infrared camera technology to do the photo work.....

Here is only picture I have been able to find.....And it deals with "funnel" capture technology...

There was a article in "The Flow" (I bleieve) a few years ago by Bill Harrison (of Creation Station) that did some pictures of plumes and capturing of said plume.... Unfortunately I do not have access or year/month of issue to share with anyone....




Dale

[Seasoned Soul]

Sooo, if I place all my duct work "Up" then my CFM doesn't have to be more than what is necessary for the surrounding work area. Hmmm* Okay so I'm back to putting it UP.

I know Susan B. and Dale(btw Thanks) mentioned intake/makeup air being brought up from underneath, what do I get to push the air UP from underneath? another Squirrel Cage Fan or inline fan? Oh my, I see the math coming on...CFM to suck it up and out...CFM to blow it in and make it all flow in harmony. AAGGHH!!!

am I way off on all of this?
Let me apologize here and now, I'm sure this info is floating around somewhere else. I've been pouring over all of this for months now trying to make the right decisions.

[houptdavid]

You do not need to push the make up air you just need an open vent whose source is 10' away from your outlet vent

[Seasoned Soul]

Okay David, I think I totally understand you (especially the glitter part)..LOL

Thanks

[pinkcb]

You know someone could make some $$ as a studio consultant! I'd pay to have someone come in and deal with getting the gas company to understand WHY I need natural gas piped in and to make sure my ventilation was adequate. Too bad geography is an issue

[Dale M.]

When dealing with ventilation ducting, just remember the lengths of duct work is cumulative... This mean an intake duct (fresh air) and a exhaust duct, does not matter that the is a big hole in the middle (studio)....

And one single fan in exhaust side will adequately pull in fresh air (make up air)

A exhaust fan running creates a low pressure area (partial vacuum) in studio, and since nature abhors a vacuum, fresh air rushes in through make up air duct/opening to fill that low pressure/partial vacuum... This is why you do not need a fan on make up air side to force air into studio...

Dale

[Dale M.]

Originally Posted by pinkcb

I'd pay to have someone come in and deal with getting the gas company to understand WHY I need natural gas piped in and to make sure my ventilation was adequate. Too bad geography is an issue

Tell gas company you are remodeling soon and studio is going away and you need gas piped in for you new GAS CLOTHES DRYER.... and it requires 2 psi pressure....

Dale

[pinkcb]

Hmmm...it's in my garage. Wonder if they'd believe that? Worth a shot.

[Dale M.]

Sure, plenty of people have washers and dryers in garages...

Dale

[Seasoned Soul]

Okay this is my plan...if someone...ahem ...would like to put any details, tips, numbers, or changes to this...I wouldn't mind, at all, especially before this happens

[oldschooltofu]

you may have seen my studio, i have both up and down, just down wont work. you dont need both, i use the down to take dust down from chipping /breaking and for cooling pieces off.

my main thing about seting up a studio is walls so the air flows from behind you, past your torch and out. your roof should be angled the other way closer to your head and sloping up toward the fan. the fan i usually put about 3-4ft above the work surface. about 2.5-4 feet from the front of the torch depending on size of torch.

you intake should be by your arms or behind you.

i should be a consultant

i just built a small station in my garage in 2 days for under 100$ in materials.

[Dale M.]

Well there needs to be a minimum 10 feet separation from fresh air intake from your exhaust outlet to insure you are bringing in clean air, remember this is the air you will be breathing because it will be right in front of you....

And funnel placement will be critical as flame plume will tend to rise up directly off torch, if your fan is weak, or funnel is to far forward there will not be enough draw to pull contaminated air into funnel....



Dale

[Seasoned Soul]

Thanks Dale and Tofu!!! Can you hear me screaming? hahaha* Okay, I'm going back to my drawing because I have to have this figured out in the next few days. I keep looking at other's studio pictures and I guess I just get more confused.

You will never know how much I appreciate your help with this. I have no DH so I'm flying solo and trying to figure this out. LE has been sooo much help in this endeavor. I'll post another (smaller) pic to see if it passes inspection if you don't mind I'd appreciate your continued feedback.

* thanks Dale for taking the time to add to my illustration

[oldschooltofu]

here is my take on your situation
put side walls on your station and remove the ducting. this will capture your plume better than just a small opening at the end of your torch.

for intake (blue lines) since your fan is only going to be 3-4' above your bench. and your bench is going to be about 3' above the ground. then your going to have to find another way for make up air to enter your room. dont know what your room/garage (hopefully something with a cement floor) looks like, but you need make up air from somewhere further away from your exhaust.

i suggest somewhere behind you, an open window or garage door perhaps will work. or you can duct it in and under and on the sides of your torch (bottom blue line). this set up is prefered because you can heat/cool the air behind you in the room and use outside air for just in the hood. this way the room stays heated/cool, and you just circulate fresh air from outside into your hood, past your torch and out your exhaust fan.

you basicly want to build a hood
like this.


sheet metal or corigated tin roofing can be difficult to work with you need snips and sheet metal self taping screws.

i have a small bench in my garage that is exactly what your doing, ill try to get some pics up tonight. im not done hooking up the fan to the hood, but youll get the idea.

side walls are exremly important and lots of people dont use them. they direct the flow of air from behind you past your torch and out. without them the air just comes from every direction into your fan and doesnt pull it away from your face. trust me i know i have worked on a station with jsut a fan in the window and i got headachs, been working at a fume hood for 10 years with no problems.

hope this helps, im off to finish mine.

[NMLinda]

I can understand your confusion when looking at others' set-ups: many people just flat out don't set up their ventilation correctly. Both Dale and oldschooltofu have given you good inputs.

The photo of the mini-hood Dale posted from Bill Harrison's article with the dotted lines is well worth studying and understanding. The text is hard to read, but what's significant about the dotted lines is that as soon as you stick a rod into the flame, it bends the spent fumes back towards your face. For that reason, if you look at Dale's additional drawings and oldschooltofu's hood, you'll see that unless the funnel/hood is over the flame, the fumes aren't drawn away from your face. Oldschooltofu makes a good point about adding sides - the fume-hood style he recommends has a great deal of safety value for the health reasons he notes.

Good Luck!
Linda

[oldschooltofu]

here is my garage station i just built
its a little short (its 2x4') (but i had to so i can fit my car in) i suggest 3x5' if you have the room for a large torch.

and i prob could have the front a little shorter, but i was going for more of a station i can stand at, rather than sit. and i have a torch holder that pulls out about a foot so essentially i have a 3 foot table

all ihave to do is connect the fan to the hood, about a 7" distance. going to use some modified 12" diameter sheet metal tubing scraps i have and make it more like 14" or 16" to fit over my fan (a 14" attic fan, little noisy but works and i already have it from a previous station)...if you can use an inline. you also dont need that big of a hole. 8" would prob be the smallest i would go.

i really should be a consultant , maybe after im done making production?

[Seasoned Soul]

hmmm, okay well I don't want to become sick, I'm just sooo claustrophobic.
I kept thinking the Sidewalls or Box would make me so uncomfortable that I wouldn't want to sit at the torch. I totally understand the importance of the CFM and the box. I really need to put some more thought into this.


again, I really appreciate everyone's time and input

[NMLinda]

It's not as claustophobic as you might think. If you're willing to get a big fan, you can make your fume hood fairly generous. I have a ~1066 cfm fan for a 4' wide by 2' deep by 28" high fume hood (I have a number of vent ducting bends....). It's not as cramped as I thought it might be.

Linda

[Dale M.]

You can also use clear polycarbonate sheeting to create "enclosure" which many not make you feel so closed in....

Dale

[Seasoned Soul]

Polycarbonate sheeting? Dale....ahem... what the heck is that? I was wondering about using plexiglass or something similar but thought it needed to be metal.

This is my set up....fill in the blank...sigh*

[Seasoned Soul]

I really like the station OldSchool, simple but ready to go. You could be mobile with that..hmmmmm*

thanks for sharing the pics

[NMLinda]

You can get clear polycarbonate - what folks think of as plexiglass - in places like Home Depot and Lowes. You'll want a metal or cement board (like that used under tile) as a backer behind the torch, but can use the polycarbonate for top and sides. It can make it feel quite open.

Oldschooltofu's hood looks like the open face is about the same as it's width, ie the hood opening is 4' high by 4' wide. Since it has sides, and just to give you an idea of how big a fan you would need if you wanted to do something like him, this would suggest a fan cfm of

1600 cfm = 4' high x 4' wide x 100

or, for a 5' wide hood as Oldschooltofu suggests you consider

2000 cfm = 4' high x 5' wide x 100

This is what you need after the static pressure impacts of any ducting for your fan (like bends or long runs of ducting). You can reduce the cfm you need if you're comfortable with a shorter opening (say 2.5' high or 3' high).

Attic fans typically do poorly with any kind of static pressure ie(air restriction), but in Oldschooltofu's case, he has a straight shot to his back wall and only 7" of ducting to deal with, which he plans to custom-make, so, from his description, his may be one of the few examples were an attic fan might work successfully. Inline vent fans (not duct booster fans like those at Home Depot) as he notes are another good choice that work well for most lampworkers, as are squirrel cage fans. You'll want to look for industrial-grade inline fans like those from Fantech or Vortex or similar squirrel cage fans, especially if you choose to do a roomy hood.

Linda

[oldschooltofu]

mobile? why? i guess if you wanted to you could move it with two guys and a truck. depends on how well constructed it is. i used 4x4s in the back for extra stability and the cross braces are a must.

btw you can get inline fans at grainger or any hydroponic store. 1600 should be plenty, if its too much you can get a dimmer for it at a hydroponic store for like 25$, then you can dial it in so you feel comfy but still have air moving by you. do a smoke test to make sure the smoke is being taken away right above the torch quickly and doesnt linger or swirl around, should be sucked right out.

if your running a larger torch or plan to, i would do the roof in metal, heat rises.

[Seasoned Soul]

you guys are brilliant... thanks sooo much for putting in the time to answer my questions and give such valuable info.
The two cabinets can be removed and spread more apart I suppose. Place "box" within. I seriously think the plexiglass sides would help me. I hear what OldSchoolTofu is saying about the metal top if I increase torch size. Might as well prepare for that now...boro calls my name. I wasn't even thinking I would need that much CFM thanks for the math Linda. Dale thanks for the idea of the polycarbonate stuff...grin*

[mewsicmama]

Thanks to all of you for all this information. I have yet to set up my studio (have everything but the space in the garage.....) and this is helping me plan much better. I do have everything - it just isn't put together yet. Darn it.

[mini]

Here's a question:
Couldn't you put the "in" vent on the bottom right of the wall & the "out" vent on the top left of the wall. That would be more than 10ft away, no?

[oldschooltofu]

Lynn: if that pics is of a window behind you, just open it a little. i just open my garage door a crack.