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Safety -- Make sure you are safe! |
2010-05-11, 4:21am
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Senior Member
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Join Date: Jun 18, 2007
Location: Delmar, Md
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Which fan?
I have a shed that is 12x16 where I do my glass and beadwork. I have decided to do a hood very similar to Mary K's from (My studio is finally done) under Studio. The measurement is 30x30x24 and will be 24" from the top of my work surface. She used a grangier blower in a plenum. I was hoping to get an inline fan instead so I would not have to make a plenum for the fan. Could someone help me with the cfm's and types of inlines. My two most important questions are...Are the inlines quiet because it will be just above my work area? and I was hoping to get a fan that I could put a variable control knob on so I could adjust the speed. I was told that some fans you cannot do this. HELP. I just want to purchase the right way the first time. Oh, and I will be doing the return air in front of my torch (Nortel Minor) just like Mary's setup. My shed is not air tight by any means and I have two windows and a door behind me. I think this is all the main info. Any suggestions would be greatly appreciated. I want to be safe!!!!!
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2010-05-11, 4:55am
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There seem to be three in-line fan manufacturers that make fans with cfm's in the range you will need: Fantech, Vortex and CanFan. I bought two Fantechs and have been very happy. Others here on LE have posted being equally happy with the other two vendors. In-line fans can be easy to install, although squirrel cage fans aren't too difficult, either.
Resist the temptation to put a control knob on your fan!! Controlling the speed is generally a bad idea! The best approach to picking a fan is to right-size it for your hood. You compromise your safety if you then try to dial it down - you won't be moving the air fast enough to extract the harmful fumes. Unfortunately, NO fan of the cfm you need is going to be quiet (even bathroom and kitchen fans, which are pretty wimpy by comparison, aren't quiet!). There are things you can do to minimize the sound a bit, however. I built a box around my fan and lined it with thick insulation as a noise baffle. A trick I've read on LE but haven't tried yet is to wrap insulation around the vent ducting to further dampen the sound. Better is to mount your fan outside if you can. The best trick, though, one I read here, is to wear an ipod with ear buds - then you don't care.....
A great resource for determining what cfm fan to get is the following site:
http://mikeaurelius.wordpress.com/ventilation-primer/
Hope that helps!
Linda
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2010-05-12, 4:13am
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LOL - Thanks so much for the info Linda. Actually I have been to Mike's website twice now and my brain hurts from the chaos of reading all the math equations. LOL - that is why I wanted a reguator knob thinking I could go bigger and dial it down cause I could not figure out what I needed.
I am definitely thinking the Ipod is the way to go if I ever figure this out.
I quit torching back in February due to the lack of a proper ventilation system...I was noticing some health issues that I could not overlook. Hopefully, I will be able to conquer this part of the process and be up and running later this summer.
Thanks for you direction.
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2010-05-12, 5:18am
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Unfortunately, even with a control knob, you still need to do the calculation..... but you suffer another concern. The cfm of a fan isn't necessarily linear with a regulator knob, and unless you have some (complicated) way to test your fan's cfm vs regulator knob position, you'll have no idea whether you have the enough cfm's or not for a given setting. It's actually easier to dig through Mike's math than try to fuss with all that, which you still need to do, anyway, to know what cfm to set the fan at. Since you've already noticed health issues associated with a lack of proper ventilation, all the more reason to get a right-size, fixed cfm fan.
I assume your vent hood will be 30" wide x 24" off the table (ie 2.5' x 2')?
If your hood has open sides, the delivered cfm you need, after accounting for static pressure losses, is
625 cfm = 2.5 x 2 x 125
If your hood is a fume hood/barley box style with an enclosed back and sides, the delivered cfm, after static pressure losses, is
500 = 2.5 x 2 x 100
How much you need to upsize the delivered cfm depends on what ducting size you use, how many bends you have, and how long your ducting run is. That's perhaps the harder part of Mike's site to work through, because there are some design choices. I'd recommend designing for 8" ducting if you have relatively short runs of ducting and minimal bends. If not, you might consider 10" ducting. Either will keep you within range of most of the good inline fans without having to go overboard on fan size (the smaller the ducting size, the greater the static pressure and therefore the bigger the fan you need to compensate).
Please don't hesitate to ask if you have more questions!
Linda
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2010-05-12, 6:20am
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Gentleman of Leisure
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Join Date: Jun 10, 2005
Location: A Little Bit West of Yosemite Valley
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Here is less numbers and more general information.... This may be better for you....
http://www.artglassanswers.com/forum...php?f=12&t=273
Dale
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San Francisco - A Few Toys Short of a Happy Meal
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2010-05-12, 7:49am
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Guys - you rock!!!!! Ok...yes the hood is 30x30 square with a height of 24" that is 24" off my work surface. I figured my cfm's to be 625 so I had done that part right.
My area where I am going to put my fan above my table will only require one bend and was considering a vortex fan which I could do an 8" ducting which I figured would cause less static but then when I get into the pie r squared and all that mumbo jumbo - I either get teary eyed or think I should take up drinking. LOL Dale...thank you for the other site - I will look at it next. And this evening after work I will try again. Linda I agree with you on the knob...way too risky. That is why I quit torching until I could get this done right.
Anyone out there that is torching with an open window and thinks this is ok.............you are fooling yourselves! PERIOD And what ever you do - don't play with silver glass at all until you get the proper setup.
Purr-Sonalities Glass Art
Kat
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2010-05-13, 4:55am
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Senior Member
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Join Date: Jun 18, 2007
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Quote:
Originally Posted by Dale M.
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Now that's what I'm talking about. One website is for the scientist at heart and one website is for me...the not so technical minded! Thanks Dale. Got what I needed from your site and ordering my safety today! Will post my progress.
Kat
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2010-05-14, 4:02am
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Join Date: Nov 21, 2008
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Glad Dale recommended ArtGlassAnswers - another excellent site with all sorts of good safety info - and I'm glad you found it helpful!
Linda
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2010-05-23, 6:11am
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Hey guys - ok...I have found a fan that is rather reasonable (?) on ebay and wanted to make sure this was ok for my 30x30x24 hood with an 8" ducting. It can be found on airboosterfans.com the item number is cf-8 model 755. I am a little confused about the cfm's though. It says that it has 755 free air cfms. Is this ok for my hood. I thought it was but before I purchase I want to make sure. It also has a 5 yr warranty...good right? Thanks for all your help guys. I forgot to mention that I will only have two bends in the ducting and the run of ducting is less that 7 feet...right above my table.
Kat
Purr-Sonalities Glass Art
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2010-05-23, 6:42am
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Gentleman of Leisure
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Join Date: Jun 10, 2005
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Quote:
Originally Posted by kitkat
Hey guys - ok...I have found a fan that is rather reasonable (?) on ebay and wanted to make sure this was ok for my 30x30x24 hood with an 8" ducting. It can be found on airboosterfans.com the item number is cf-8 model 755. I am a little confused about the cfm's though. It says that it has 755 free air cfms. Is this ok for my hood. I thought it was but before I purchase I want to make sure. It also has a 5 yr warranty...good right? Thanks for all your help guys. I forgot to mention that I will only have two bends in the ducting and the run of ducting is less that 7 feet...right above my table.
Kat
Purr-Sonalities Glass Art
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ALWAYS use the "free air" value for CFM .. DO NOT USE or believe the booster cfm value as you are not in a "booster" situation....
As for actual CFM the value is about right for hood size....
Dale
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San Francisco - A Few Toys Short of a Happy Meal
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2010-05-23, 8:28am
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Could the value be better for my hood size...or should I change my hood size to make it work for this fan? The company that is going to make the hood suggested I have a hood made to the size of the area which is 30x36 - and it would only be a few $$$ more.
Kat
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2010-05-24, 7:13am
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The fan seems reasonable with what I could see on the website. With only 1 bend, your static pressure losses should be low if you stay with 8" ducting. You could probably increase your hood to 36" wide. If you find that you need more draw, you can always add a back and sides to your hood.
Linda
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2010-06-08, 2:40pm
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Heart of Flame
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Join Date: Apr 28, 2010
Location: Ontario, Canada
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Thanks for posting this KitKat - it is very timely for me! I am also setting up my studio and want to get things right!
I have seen this system online where the iline fan cfm is around 260 but there is no hood only ducting www.andreaguarino.com/ventilation/ (hope I posted that link alright)...can I ask all of you what you think of this system as opposed to using a hood above with an inline fan?
Thanks!
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2010-06-09, 5:33am
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Unfortunately, there seems to be no information available on how to design these for an appropriate level of safety, unlike the hood style which has well-established industrial application, safety criteria and design standards. This approach works against the physics of hot air rising, in our case the hot spent combustion products produced by the torch. It's hard to see how this would be effective at capturing all of the fumes produced by the flame and keeping them safely away from one's face. Also, to my knowledge, no one has ever posted a smoke test for this approach to see how well it really works. As interesting as it is, I wouldn't trust my lungs to it without a lot more information than seems to be available.
Linda
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2010-06-09, 6:24am
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ILERNTITBYWATCHINU
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Join Date: Mar 26, 2010
Location: arnold ,ca
Posts: 188
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have you checked with any of your local HVAC contractors to see if any of them have an extra fan sitting around. i got mine from the first shop i went to . i walked in and told them what i was doing and how big my shop was. they did a little simple math and came out of the back of the shop with a fan for me. it was purchased for another job and they never used. it had been on the bench for a while and they were more than happy to let it go for next to nothing.
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2010-06-09, 12:57pm
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needs creative tagline
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Join Date: Feb 01, 2008
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I agree with Linda that its really unfortunate there isn't much info on those setups, because a lot of people are using them! I know that Andrea is a great person who is concerned about her own health and that of her students, so I am sure that she believes the system is effective. But whether there is any scientific evidence to back that up, I don't know of any. I have a friend with that setup too. She says she did a smoke test and it worked great. But, no video and now she has moved.
so, if you are willing to take a chance and do the work to try it out, please do lots of testing and take video to share with the community! If you are not willing to be a human guinea pig, I think we will all understand (I personally would not be willing myself...). I would be especially curious to see how it works for different kinds of activities - example, I do some blown boro stuff like making goblets, and it seems to me like this might deflect and disrupt things a lot more than say, making small beads.
Linda - a question for you - I have an acquaintance who claims that although the gases like CO and NOx and such are hot, they are also heavier than air and will tend to want to come back down rather than rise. So I have wondered if the people with makeup air coming in low (say under table) are helping themselves out by pushing the gases up into the hood to get exhausted. Do you have any thoughts on that vs having makeup air coming in high?
laura
ps. berningglass is right - as has been suggested by several people, good cheap fans can be easily had at HVAC shops! Personally I'd do the math first myself cause i have trust issues
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Lynx with OGSI-15 and big holding tank, Redmax on tanked, and National 3b that swings both ways...
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2010-06-11, 10:46am
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Quote:
Originally Posted by yamaha200
Linda - a question for you - I have an acquaintance who claims that although the gases like CO and NOx and such are hot, they are also heavier than air and will tend to want to come back down rather than rise. So I have wondered if the people with makeup air coming in low (say under table) are helping themselves out by pushing the gases up into the hood to get exhausted. Do you have any thoughts on that vs having makeup air coming in high?
laura
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Most of us work with our faces closer to the torch's exhaust plume than we realize (especially those of us who are short, like me). This raises the probability considerably that, if the CO and NOx fumes aren't extracted quickly and efficiently, one could still breathe them before they MIGHT have a chance to sink. Your aquaintance has brought up an interesting thought, but given the turbulence caused by moving around while working at the torch, the thrust force of the flame in addition to temperature effects, I think it's hard to say whether C0 or N0x products actually sink or not in pratice. That said, you have an interesting thought that make-up air coming in low at work-surface height - especially if the vents are located optimally - may perhaps provide an advantage in moving bad products up and out faster. PJ/Cheng076 posted a very interesting set of pictures in his "Mini Studio Vent tests" thread that you and others might want to check out:
http://www.lampworketc.com/forums/sh...d.php?t=157660
I think our collective goal is to figure out how to have the most efficient ventilation systems we can.
Sorry to hijack your thread, kitkat. Hope the make-up air question is also helpful to you.
Linda
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2010-06-14, 4:07am
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I am very happy to have my thread hijacked. Knowledge is found thru questions and answers. Come on everyone...pack your bags and hop on board. I love info and all of this is great! "wd2crv" - please don't take your health for granted. I think it is wonderful that you are taking the initiative to find the right system for you. I did the same thing and I found that Mary K's setup (TO ME) is just the poster child for EVERYTHING! Exhaust, makeup air, layout...everything. I will be adding my own personal touches however but as far as the mechanics - it is perfect and one of the reasons is because of the makeup air. At the back of the table from underneath makes alot of sense. I also have a window behind me for additional air when weather permits.
Update - I did choose the fan from the link above and my hood has been made and hopefully the whole setup will be completed in the next two weeks so I can get back on the torch! I am uping my amperage to my shed because I have my oxycon, air conditioner, lighting, kiln and now my fan...it could blow my breakers. So, please take that into consideration also. As always, stay safe and have fun.
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2010-06-14, 9:59am
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Yes, PJ's thread was very informative, and a while back PJ even added a extra test just for me! I'm very curious to see how my full scale results compare with the small test once i get around to my final makeup air arrangement. For now i'm just using a big open window...
laura
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Lynx with OGSI-15 and big holding tank, Redmax on tanked, and National 3b that swings both ways...
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2010-06-14, 8:58pm
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Heart of Flame
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Thanks KitKat - will there be pictures of the finished product?
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2010-08-03, 1:21pm
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Hey guys...Dale if you are around - I need your help...I got my hood and my fan and everything is setup. I plugged the fan in and it literally was barely able to pull a cigarette (I don't smoke - the contrators) plume up the hood opening. What is wrong? I am in tears...I am seriously having a melt down. I have worked so friggin hard to research everything and get the hood made the right way - 24x36x24 - hood had to be put 31" off the work surface in order to get it thru a ceiling joist - only one bend in the 8" ducting and it will not pull anything. I mean - it will swirl around a bit but I could have gotten way more exhaust with a window fan!!!!! What have I done wrong. The contractor guy went home for the day and is coming back tomorrow - he thinks everything is fine. They just don't get it.
HELP PLEASE IF ANYONE IS READING THIS - PLEASE LEAVE SUGGESTIONS...I DON'T WANT TO THROW IN THE TOWEL.
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2010-08-03, 1:22pm
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Senior Member
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Linda - are you available. I am just so upset that my fan is not pulling any of the smoke up the hood. I am just so stressed...any suggestions
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2010-08-03, 3:52pm
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Gentleman of Leisure
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Fan should be pulling up smoke somewhat vigorously..... Are you sure fan is functioning properly.... Maybe some packing material in fan inlet... Is duct work "clear" no raccoons or owls built a nest in duct overnight.... How about make up air is it available, is door/window/vent open?
Dale
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San Francisco - A Few Toys Short of a Happy Meal
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2010-08-24, 12:43pm
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KitKat - Sorry I didn't see this sooner - How are you doing with your fan?? Did your HVAC guy come back out? Were you able to get up and going?
Linda
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2010-08-25, 1:09pm
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Just at the begining
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Join Date: Jul 13, 2009
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Quote:
Originally Posted by NMLinda
Unfortunately, there seems to be no information available on how to design these for an appropriate level of safety, unlike the hood style which has well-established industrial application, safety criteria and design standards. This approach works against the physics of hot air rising, in our case the hot spent combustion products produced by the torch. It's hard to see how this would be effective at capturing all of the fumes produced by the flame and keeping them safely away from one's face. Also, to my knowledge, no one has ever posted a smoke test for this approach to see how well it really works. As interesting as it is, I wouldn't trust my lungs to it without a lot more information than seems to be available.
Linda
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This type of setup requires higher CFM at the opening, The math relies on capture distance from torch to duct opening, they do work but it's very important that you do not work outside of this area. The capture distance is roughly 1.5 times the duct diameter or face, that's why they put cones on the duct to increase the capture area. The picture shows flex which is still taboo, even in this setup.
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2010-08-26, 3:13pm
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Do you happen to have any links or info on the correct way to design these systems and the principles behind their operation?
Be much appreciated
Linda
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2010-08-26, 6:14pm
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Just at the begining
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Join Date: Jul 13, 2009
Location: Barrie, Ontario
Posts: 131
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here's a link with some info.
http://www.engineeringtoolbox.com/ex...et-d_1008.html
I'll have to dig out my old textbooks for more info, but you can see as you move farther away the capture (VC) drops, by flaring the end it acts like a larger duct. at 1.5 times the capture is almost zero (2 or 3%), but you want your flame aimed at the center of opening for maximum efficiency.
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2010-08-27, 4:33am
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Thank you!
In reading this, air volume flow looks like one of the key design parameters, and, as you point out, extraction efficiency drops quickly with distance. This is one of the concerns I've had with lampworking applications of this idea where the duct opening is aimed underneath the flame. I'd be interested in your thoughts on proper orientation of this kind of extractor and whether there are any OSHA recommended air volume flow rates you know of for the kinds of fumes we deal with.
Linda
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2010-08-28, 3:48pm
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Senior Member
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Hey Guys: I am still working on my hood and install of return air vents...but I also have a question about what I will need to get my propane outside and setup. Does anyone know what I will need. Right now I have the normal red/green hoses to hook up with my regulator. So...does anyone have a link to info for taking it thru the wall and (HOPEFULLY) limited materials to do so?!?
The hood and 745 cfm fan is working great! I did a smoke test and am pleased with the outcome. I am now trying to get everything else setup and then I will post pics for everytone.
Linda - that's ok. Yeah I was able to get him back out here cause I had not pd him in full yet! SMART on my part! He got back quickly to finish it the right way!
Anyway - if anyone can help with the propane - I also was wondering what everyone puts over their tanks to keep it safe.
Kat
Purr-Sonalities Glass Art
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2010-08-29, 2:14pm
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Senior Member
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Hi Kat - glad to hear your HVAC guy came back to do the install right (good thing you didn't pay him in full until you knew it worked!!).
There have been a couple of good threads either here in Safety or in Studio showing how different members protect their propane tanks from weather. A popular approach seems to be using a rubbermaid garden hose storage unit. Folks cut holes in the bottom so that any propane that might leak doesn't get trapped. You might search on those threads.
A great place to find out how to bring propane through a wall from the outside is the Art Glass Answers forum ( www.artglassanswers.com). If you sign up as a member, you can see the drawings and pictures, which will be important to helping you with your question. Dale M has some very helpful drawings on how to do that he's posted over there. Also, DeAnne/TheGlassZone has a great tut (think it's a sticky over in the free part of Tutorials). She has a great how-to with photos so that you can see what the parts look like.
If you have more questions when you get a chance to look at those resources, please come back!
Linda
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