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Spray booth extraction
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=16273		 Page 1 of 1
Author:  Andy Matthews [ Thu Mar 06, 2008 6:58 am ]
Post subject:  Spray booth extraction
This topic's starting to give me a headache! gaah

I've been attempting to read up on the subject, but I know so little about it I'm finding it hard. So far I know that I'm going to need an explosion proof fan if I'm spraying solvent based finishes. I don't yet know how to work out the CFM rating I'll need for a certain sized booth, nor can I think of an effective way to heat the booth (I'll be drawing air for the extraction from outside.

I'm sure some of you guys will have been through this process before and I could really do with some help [uncle]
Author:  Colby Horton [ Thu Mar 06, 2008 9:35 am ]
Post subject:  Re: Spray booth extraction
I'm guessing you're talking about a walk in room type booth. I have a spray booth that works pretty good but it's not a walk in room. It is just a 4x 4x 4 plywood box that is set up on a frame. I have a pipe (9" i think) coming out of the back wall of the booth that goes into a blower. Then the exhaust pipe from the blower connects to a shut off thingy I made that is mounted in a window. This booth is upstairs in a two story building. For intake air, I open a window downstairs and stick a little ceramic heater in it. That way the air that is coming into the shop is mostly warm and dry. Anyway, it works pretty good. I'm sure it wouldn't pass official safety standards though. The explosion proof blower has two speeds. I use the slow speed so it has way plenty of cfm. Not sure if any of this will help but here it is anyway.
Author:  DannyV [ Thu Mar 06, 2008 9:50 am ]
Post subject:  Re: Spray booth extraction
Good timing. I just installed a 3200 CFM explosion proof fan into a 10 x 16 spray room. It has HUGE air movement. I'm going to look into whether I can use a rheostat for the switch. Running full tilt it will be great when spraying but I would like to idle it down a bit for drying and off gassing. Hopefully this can be a bit of a benchmark for you.

Heating is an issue and I would really like to hear other peoples ideas on. I have yet to solve that one. One of my friends has suggested radiant heaters. Some automotive shops blow in filtered forced air heat. The setup my friend has is pretty expensive. Let me know if you come up with any other ideas.

Good luck and I hope some others will chime in.

Cheers,
Danny
Author:  grumpy [ Thu Mar 06, 2008 10:41 am ]
Post subject:  Re: Spray booth extraction
I run a small, 90 CFM fan for between coats and while curing.... Since the main fan pulled out all the volatile mist(I do let it run a minute or so after spraying), I feel safe running just the little guy afterward.

Some google legwork will give you the formula for calculating your main fan's CFM requirements; it's based on your booth's volume.
Author:  Andy Matthews [ Thu Mar 06, 2008 12:27 pm ]
Post subject:  Re: Spray booth extraction
DannyV wrote:
Good timing. I just installed a 3200 CFM explosion proof fan into a 10 x 16 spray room. It has HUGE air movement. I'm going to look into whether I can use a rheostat for the switch. Running full tilt it will be great when spraying but I would like to idle it down a bit for drying and off gassing. Hopefully this can be a bit of a benchmark for you.

Heating is an issue and I would really like to hear other peoples ideas on. I have yet to solve that one. One of my friends has suggested radiant heaters. Some automotive shops blow in filtered forced air heat. The setup my friend has is pretty expensive. Let me know if you come up with any other ideas.

Good luck and I hope some others will chime in.

Cheers,
Danny


A benchmark indeed! My room will be 6x8 feet, so I could well be looking at around a 1500CFM fan. What kind of fan is it that you're using? I was also considering the use of a radiant heater (like the one I use in my shop), a small oil-filled radiator.

I laid the flags to sit the new booth (shed) on today - went well! Please do ignore the wall behind, it's due for a re-build!

http://www.darkmatterguitars.com/siteim ... 308/01.jpg
Author:  DannyV [ Fri Mar 07, 2008 10:59 am ]
Post subject:  Re: Spray booth extraction
grumpy wrote:
I run a small, 90 CFM fan for between coats and while curing.... Since the main fan pulled out all the volatile mist(I do let it run a minute or so after spraying), I feel safe running just the little guy afterward.

Some google legwork will give you the formula for calculating your main fan's CFM requirements; it's based on your booth's volume.


Good one. Wish I had thought of that before finishing the room.

The fan I use is a Canadian made through wall type. I found that it wasn't my room requirements but what is available. This was the only some what affordable fan I could find in my part of the world.
Author:  Andy Matthews [ Sat Mar 08, 2008 8:49 am ]
Post subject:  Re: Spray booth extraction
Just thought I'd give this a little bump incase anyone else would like to chime in :)

I've been looking round to try and find these CFM calculations, but I'm not having much luck - don't think I'm googling the correct words or something. I've managed to find one web-based calculator but it's asking for a value in minutes of how long it should take to clear the room - something I'm not too sure of! Does one minute seem acceptable?
Author:  Rick Turner [ Sat Mar 08, 2008 11:23 am ]
Post subject:  Re: Spray booth extraction
I don't know how anyone is going to heat enough air with little heaters like you guys are talking about to do anything but drive up your electric bill a bit. You need serious CFM with a safe spray booth, especially if you're shooting finishes with volatile solvents. I'd suggest looking at the small Grizzly booth or go on the Binks site and look at spray booths or look here for some info:

http://paintboothtechnologies.com/OpenBooth.html

I've got the equivalent of their PBT-OB-0807
Author:  d1camero [ Sun Mar 09, 2008 7:48 am ]
Post subject:  Re: Spray booth extraction
Here are some sites from my searches a while back:


http://www.briansmodelcars.com/tutorial ... &CurPage=1

http://www.highlandwoodworking.com/inde ... stom&ID=88

http://www.samsrc.com/paintbooth.htm


I have built a 4 x 4 x 3 plywood downdraft booth, with the front side open. It is about 7' tall. I used a 2000CFM enclosed motor/blower from a used dust collector. I was disappointed when first powering it up because I could not feel anything pull, however it really works quite well. I can spray with two part auto lacquer and someone standing 3 ft behind me cannot smell anything. I have it in my heated basement, venting to outside - right at my *(&#$ neighbors...


d1
Author:  Andy Matthews [ Sun Mar 09, 2008 8:09 am ]
Post subject:  Re: Spray booth extraction
Thanks! Those links look great. I'll get reading :D
Author:  Rick Turner [ Sun Mar 09, 2008 7:28 pm ]
Post subject:  Re: Spray booth extraction
Oh, don't bother trying to put a rheostat on an induction motor unless you want melting wires and such. The speed of such motors is determined by line frequency and the number of coils in the motor, not by voltage or line "choppers". The only way to control speed of standard spray booth motors is probably not worth the dough it takes to do it. You'd have to install a variable frequency motor drive inverter...
Author:  DannyV [ Sun Mar 09, 2008 8:20 pm ]
Post subject:  Re: Spray booth extraction
Thanks Rick,

Just ran into my electrician buddy who did the explosion proof fittings for me. He told me the exact same thing. May take some of the wall covering off and put in something small just to move some fumes out...... one day.
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