ventilation help

Chemwapuwa · #1 2010-10-04, 9:30pm

ok i have been reading this forum for a while on ventilation and my head is spinning. i have just rented a studio in an old factory building with two huge windows 15' tall i think, they are side by side and i will need to setup my ventilation. I was thinking of doing the funnel method.

i just don't know what i need, in regards to the fan and duct work. I will have a hh with propane to start, upgrade to lynx when i feel comfortable.

here are my questions;

1. my duct work doesnt need any bends. what is the min length of duct work do i need between the torch and the fan.

2. what fan should i use. what is the min cfm do i need

3. do i need that box / enclosure thing around the torch area.

4. i was thinking of doing this ventilation setup would it work for me.
http://www.andreaguarino.com/ventilation/ i dont want anything that is perminate, i need something portable. i will only be at this studio for a year at the most and then i will have a real private studio....

well i guess that is all for now, any help would be great. i think i just overloaded myself with all the different ways to do this. i just need direction to what i need to do.

thanks for the help.

JoeDeM · #2 2010-10-05, 9:40am

Quote:

Originally Posted by Dale M.

Suggest you read more in the safety section, particularly articles on different types of ventilation.... The funnel method is certainly becoming popular, but for the moment there is no design criteria on how to assemble a effective system and there is little evidence (visual test results) on whether a funnel design actual works...

About only thing most people state is they are using fans in about the 800cfm range and the the "systems works good", but to me the phrase "system works good" is not definite proof of sufficient air flow and proper capture of combustion by products and heavy metals releases by glass in flame...

I would really like to see results of funnel system using a smoke test before I ventured in that area if I were developing a funnel setup for my studio...

Dale

Nothing beats a good barley box setup with make up air, that said as long as you stay in the capture area of the cone you are safe. People use large CFM as a brute force method to ensure capture of fine partials, and products of combustion. Capture Distance 1 duct/or cone diameter MAX. The industry standard is 1.5 (welding) but for what we do I don't think it's safe, just my opinion

Here's a simple example 10" @ 850cfm 1559fpm capture at 0"
distance 8" CAPTURE velocity =170 fpm capture
distance 10" CAPTURE velocity =113 fpm capture
distance 12" CAPTURE velocity =80.6 fpm capture
distance 15" CAPTURE velocity =52.5 fpm capture

you can see how quickly it drops, think of it like a vacuum cleaner, it's very powerful at the zero point, but as you slowly pull it away it gets weaker and weaker.

Note: this doesn't take into consideration SP loss in the duct, but it's usually short anyways.

Chemwapuwa · #3 2010-10-08, 6:10pm

thanks Joe, but i even more lost, i have looked into the barley box and i like it, im just not sure on how big the box or the fan has to be. ill keep looking for an answer and maybe some directions on setting up a lynx.

Chemwapuwa · #4 2010-10-08, 11:29pm

Ok this is what i have thought of doing so far,

get this fan

http://cgi.ebay.com/New-8-Inch-Inlin...item230aa72a90

Im using the same setup with a metal barley box like lorraine's

http://www.lampworketc.com/forums/sh...trailer+studio

my only concern is the shelving is only 24" deep is this ok with a lynx and a hothead.

http://www.homedepot.com/Storage-Org...atalogId=10053

i can put the shelf as close as i want to the window so, i will only need one bend

im not sure where to put the fan would it be at the brginning of the duct work with a bend and then a straight pipe out the window. or do i put the fan after the pipe on the outside of the window. ( hope that made sense)

my goodness this stuff can give you a headache and eye ache with all the reading and numbers

thanks all for your help

Dale M. · #5 2010-10-09, 7:48am

Fan location is not critical.... Further away from you it is the quieter it will be (maybe not much but some)... Mostly its a case where it is easiest to mount and connect duct to..

Dale

Chemwapuwa · #6 2010-10-09, 7:53am

Thanks dale

Chemwapuwa · #7 2010-10-11, 10:21am

ok another idea, i understand the importance of cfm, i was wondering if instead of a high cfm version i could us two lower cfms say two 300s, i was thinking what is i had two fans in my barley box. the dimentions of the barley box would be would be 24"H x 48"W x 24"D would this work.

Lorraine Chandler · #8 2010-10-13, 10:11pm

Hi Louise, We have the same workbench. My fan is three speeds with the lowest at 1100 CFM. The highest speed is like a jet engine at 1600 CFM.

I have to have a patio door open or two large windows in the other room because of replacement air needs at 1100 to 1600. The flame was very turbulent until we got enough replacement air figured out. Now it's great.

I use a lot of frits, silver foils, enamels etc. it is also my soldering area so I want those fumes whisked away! and the fumes when the kiln is running.

Chemwapuwa · #9 2010-10-14, 9:36pm

thanks for the help as always your the best lorraine,

i think im almost done and should be able to work with some glass soon....

I changed the dimentions of the box, my uncle thought 24" high wasnt enough so now i have a 28"w x 30"h X 24"d, the opening in front will be about 20" once i put something to eclose the front better.

what would you think would be a good fan cfm, i had one guy from the local grainger store say i would only need between 200 n 300 anything too big would be too much, and cool things down too much.

the vent hole is on top near the back of the box

Lorraine Chandler · #10 2010-10-14, 10:22pm

Hi there, glad to hear you are almost there. Exciting isn't it?

Here is a link that may help you get an overall idea of what goes on with ventilation. Building a proper ventilation system does encompass more than just a hood and exhaust.

http://www.artglassanswers.com/forum...php?f=12&t=273

I just noticed Dales heading for the link I gave you. I was in no way suggesting you or anyone else is a dummy. I apologize if you thought that. I wouldn't hurt anyones feelings on purpose ever.

Please accept my heartfelt apologies? The article is so all inclusive I refer to it frequently and have linked others to it but this is the first time I noticed the heading and that it could be interpreted negatively when used as a link.

Dale M. · #11 2010-10-15, 8:45am

A 28 x 30 inch face opening hood should have at lease 730Cfm...

It is recommended by may different health and safety regurgitation taht regulate the industries that manufacture and use fume hoods that you have at lease 100 cfm per square foot of face opening of a hood or fume cabinet..

A better recommendation for your health and safety is 125cfm for a open hood, so I base all the calculation I do on the 125cfm whether its a open canopy hood (kitchen range style) or fume cabinet...

So...

28 x 30 = 840 sq-inches

840 / 144 (sq in one sq ft) = 5.8 sq-ft (face opening)

5.8 sq-ft x 125 CFM = 729 cfm

Or your smaller opening...

20 x 30 = 600 sq-in

600 / 144 = 4.16 sq-ft

4.16 X 125 cfm = 520 cfm

So the Granger Guy is off by about 300 cfm or more because he has no knowledge or experience with what you are actually doing and how a correct ventilation system for warm glass work is designed or calculated.

Also to be considered in vent hood calculations are size of duct (diameter) length of duct run, type of duct material and number of bends (45° or 90°) and static pressure fan will work against. As static pressures in "system" go up, fan efficiency goes down so the static pressure chart on fan specification sheet is important. These all have a positive or negative influence on actual air flow in your "safe" breathing zone...

You may want to look over most of this section of AGA forum....

http://www.artglassanswers.com/forum/viewforum.php?f=22

Dale