Bathroom fans have had to be brushless and sparlless since the early '80s to meet building codes. I have been using a bathroom fan in my booth for over 20 years and no explosions! I have been a custom painter for all that time and have done thousands of paint jobs and used to use solvent paints almost exclusively.
Jay
C-415 Build: https://imageshack.com/a/tShC/1
Other builds: https://imageshack.com/my/albums
The laptop PS I referred to was to power the Bilge fan. It's a brick type of PS, not like one found in a desktop PC.
Old computer fans are brushless. The question is how much air do they move? They are designed to blow air over a little metal box. You will be asking it to suck a large quantity of air from a relatively big area and then blow it out some sort of ductwork. That's a lot more work. If I were using computer fans I would get the biggest ones I could and use two or more of them. I used a squirrel cage fan from Grainger.
Dave H. Painted side goes up. My website : wnbranch.com
I was considering using one of my extra Laptop Pwer Supplies. Whatch think?
Specifications:
Input: 100/240 Volts AC 50-60 Hz
Output: 12 Volt DC 7 Amp (12V, 7A)
I would expect a bilge fan to be explosion proof, since the idea is to vent everything, including gasoline vapors, from the boat's bilge. Only issue is, you will need a fairly hefty 12V power supply. Specs say 5.5 amps, you'll want a 6 or 7 amp power supply, 12V DC. Or use one of those car battery eliminators with sufficient capacity - unless boats are that different, the actual voltage is 13.8 V DC.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Hi guys,I found an inexpensive bilge fan that should work just fine on Amazon for about $29 including freight. It would be easy to connect to 4" ducting.http://www.amazon.com/gp/product/B00D96LYSY/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A10KONGIV6WPUI
I contacted the manufacturer and they said that their in line blowers are ignition protected when I asked "Is your YELLOWTAIL™ 4” Blower explosion proof regarding gasoline and solvent vapors?". Spec Sheet:http://pdf.nauticexpo.com/pdf/shurflo/yellowtail-blower-277-3100/21582-56967.htmlI'm going to buy one and start my booth project!
Have fun!
Dan
ONe of the things you may want to do is to look at how OEMs buid them and then reverse engineer to your requirements/capabilities. Here is an example of a down draft with 3 stage filter. You could build something like this and use their filters for example. Here it looks like the floor is one of the filters. Also note 185CFM rated fan, there are losses through the 3 stage filters which will make it's effect on spray pattern much less.
http://www.micromark.com/15-inch-x-20-inch-standard-spray-paint-booth,8034.html
If I were building one, I would consider buying these filters and replacement window as well as an inexpensive bilge blower motor and fabricate accordingly. Use thin gage sheet metal--cut/bend and pop rivet and seal the sides, etc. I suspect these filters on the floor rest on an expanded metal screen of some type(pop rivet with washers).
Richard
sverk Thanks maxman! My problem then is I don't have the January -88, nor the February -93. And I am not ready to shell out the money for the 75-years MR DVDs. The Jan-88 issue is no longer available as a back issue. Wha other opitions mingt there be? Sverk
Thanks maxman!
My problem then is I don't have the January -88, nor the February -93. And I am not ready to shell out the money for the 75-years MR DVDs.
The Jan-88 issue is no longer available as a back issue. Wha other opitions mingt there be?
Sverk
I looked up the February 1993 article and all that was was a question regarding how to size the fan. It was only two paragraphs. They gave a formula to determine the approximate CFM (cubic feet per minute) a fan would move. They said that a booth should exhaust at a rate of at least 100 cubic feet per minute. The formula was to divide the fan's rated CFM by the booth opening in square feet. Then they added "at least" 20 CFM per 5 feet of exhaust duct length to allow for the duct resistance.
Regarding the January 1988 issue, you could contact MR customer service and ask if they would copy the article for you. If they can't do that, then I see no reason why someone couldn't copy the article for you.
Or, if there are train shows around you, you might be able to pick up a copy of the magazine.
sverkAbout the Model Railroader article mentioned: Does it contain a description of how to build a spray booth,
Yes, the Paint Shop Spray Booth has instructions. See my post just above with the correct issue.
Thanks to you all for the very useful comments and advice and for the very thorough discussion and tech info from DELRAY 1967. Great!
Clearly, the old kitchen fan is out of question.
I also have a squirrel cage type fan with motor outside the case, could be ok -- or not quite. It is rated 2.4 m^3 / min, which should be about 80 CFM.
Looked for bilge blowers, what I find in boating departments (Sweden) are called "engine room fans". They are axial fans with the motor in the middle of the airflow. Nevertheless they are said to be "spark free" -- they had better, given where and for what they are to be used. And that would seem to be safe enough for small airbrushing booths as well, right?
They are low price, 12 VDC (I have a good source for that) and allow easy mounting because they couple directly to circular duct at both ends, and thus could be placed anywhere along it, not necessarily in or at the booth.
Does that seem ok?
About the Model Railroader article mentioned: Does it contain a description of how to build a spray booth, or what? Would be great, but the reference was not right, hope someone can find the right one.
Thanks!
sverk I dug out my MR of January 1981, but I don't see anything about airbrushing or booths in there. Neither on page 70 or anywhere in that issue. Did you mistype the year or month?
I dug out my MR of January 1981, but I don't see anything about airbrushing or booths in there.
Neither on page 70 or anywhere in that issue.
Did you mistype the year or month?
If you are looking for the article on building a spray booth, it was called Paint Shop Spray Booth and was in the January 1988 issue of MR. I built one from that article.
Searching the magazine index, I see that there was also an Ask Paint Shop article with the subheading Exhaust Fan for Spray Booth in the February 1993 issue. I didn't look to see if this was a discussion of fans or something else.
I built my own spray booth a few years ago; google "what size blower for spray booth' or something similar. Don't only read the hobby oriented results, what you are looking for is the mechanics of how a spray booth operates. I was surprised to find out there's a lot more to it than putting a fan on a box. Aside from my home spray booth, I rigged one up in my apartment I stay at for work. Basically, I have a workbench in front of a window on which I put a box 'funnel' for containing overspray. The fan is in the other room, blowing air in, pressurizing the apt. With only the 2 windows open (one for the fan, and one for the workbench 'funnel'), it creates a pretty good evacuation of fumes. The more windows open (or any other air leaks in the house), the less 'pull' the spraybooth has.
If you want to figure out a real spray booth (like I tried to do), here is a pretty good page for general spraybooth formulas and other things to think about:
http://www.modelersite.com/Abr2003/english/Spray-booth-design_Eng.htm
I spent about a month doing research; since I don't trust any one, single, page with info on it, I look at dozens and average the ideas I've read about in all the sources. Another source for used blower fans is a local HVAC shop...the kind that installs new furnaces, etc. My local shop said to check the dumpster behind their shop in the mornings for furnace blowers, ducts, etc that were removed from peoples' homes. BE SURE to clear this with someone at the shop first, you don't want to get in trouble for stealing scrap metal!
Be safe, be smart, if your booth doesn't evacuate the fumes, which are heavier than air, you could have a fire inside your house if the fumes creep over to a water heater, or other ignition source. Don't forget your pets that live near the floor (or kids crawling around); they could become pretty sick from inhaling the fumes.
I love this hobby!...so many things to learn about! :)
http://delray1967.shutterfly.com/pictures/5
SEMI Free-Mo@groups.io
January 1981 MR Page 70
Most AC motors do not have brushes or slip rings. The exceptions are high torque wound rotor motors like you see in power tools.
That being said, it is still best to keep the motor and wiring out of the airstream as problems do happen. What you want is a squirrel cage blower (not to be confused with a squirrel cage motor). These are available in multiple sizes in places like hardware stores and online from outfits like Granger or McMaster Carr, among others. These have a motor set to the side with a cylindrical shaped blower fan.
As an example:
http://www.grainger.com/Grainger/DAYTON-PSC-Blower-1TDR3?cm_sp=IO-_-IDP-_-RR_VTV70300505&cm_vc=IDPRRZ1
For size, you want a CFM rating that makes about 100 ft/min velocity at the open side of the hood. (CFM / ft^2 opening = ft / min.) For a 1 ft x 2 ft opening in the side of the hood this is about 200 CFM.
Lights and light switches should also be mounted outside the hood. They can shine in through a transparent or translucent panel in the side of the hood.
There should be a filter at the back of the hood to remove paint particles. This will not strain out chemical fumes but it keeps the duct and fan from being coated with paint.
The fan should be exhausted outside.
The ductwork should be metal stovepipe.
The bilge blower mentioned above will work fine if it is large enough and operates on 110VAC. If it uses, say, 12VDC it needs a power supply.
MR had an article on this back in the 70's. Maybe someone with the DVD set can look it up.
Bilge Blowers are cheap and safe. Get one that is U.S.C.G. Approved and you should have no worries. 100CFM would be plenty I would think, unless you are building a walk in type spray booth. Last I checked Wally-World had them. If not they are online at the boating supply stores.
Give us some pics when you get through. I, for one, would like to see how it comes out!
Steve
There are many motors designed for hazardous areas. As I said above and guess I need to reinforce with the link below, here is one USCG approved--what I call a torpedo type motor used to vent highly volatile fuel from bilge areas.
http://www.boatus.com/boattech/articles/bilge-blowers.asp
Aren't some bath fans explosion proof?
A brushless motor is a lot more free wheeling and will require a 3 wire controller. Pretty expensive due in part because of the controller(esc). A good filter in front of the fan is important. Sometimes you can find brushed motors approved for a certain level of hazardous conditions with proper sealing. What you want to avoid is the spark. In marine applications that is done with canned motors and sealant. So, you could use any can type motor and seal it up. Don't have the fan real close to the paint area, ie use a filter and between that and normal dissipation you should be fine.
You don't want so much windage that you affect the paint spray being applied, so the fan you are speaking of may be over doing it if it's real close to the paint application area?
My guess is that your motor is the brushless type. That said, I wouldn't use any type of fan where the air path is around the motor. The better option would be a squirrel type fan with the motor located outside of the air path. I would rather be safe than sorry and a solvent vapor explosion/fire can be very fierce.
Joe
Hi,
I am thinking about building a spray paint booth for weathering and painting HO scale models. It would use a duct to blow fumes to the outside of the house.
Long ago I think I've heard about the possible risk of explosion in the fumes when painting with lacquer type paints (Floquil etc). How big is that risk?
For a fan I consider using one from a retired kitchen above-stove fan. It is a tangential ("squirrel wheel") type and the motor is located in the center such that the incoming air and fumes pass all around it. I figure if the motor makes sparks it could ignite the fumes if they happen to be the right, well bad, mix with air.
I suppose brushless motors don't make sparks so that would take care of it, but how do I recognize an old brushless from a brush-type motor?
Comments and advice appreciated,
Thanks in advance,