Building a paint booth - 2 Quick Questions

[adampolo13]

I've read a ton of reference articles and watched all the build logs on SMA and I had 2 Quick Questions based on your experiences.
1. Do you guys know what CFM rating Fan I should purchase for the booth?
2. Fan Placement, bottom, back, top? I've seen examples of all 3.

Thanks a ton!

Adam

 

[TBadger]

You'll have to calculate the static pressure of the enclosure to create a suction....which will dictate your cfm. I see most fans at the rear or below the deck. Above would suck paint away I think.

Good Luck on your booth build and finding a new place in CT or RI

 

[adampolo13]

Thanks Badger! Good news is my father-in-law gave me the green light to set up a work station in his wood shop and its really not that dusty. Long story short he has a sweet dust extraction system. Now all I have to do is figure out how to calculate static pressure. I have no idea what that is.... Hahaha

 

[hooterville75]

Everything you need to determine how many CFM's you need are in this article. Enjoy!!!!

http://www.briansmodelcars.com/tutorials/tutorial/23

 

[TBadger]

Simply Length x Width to get square feet x50 So 2ftx 2ft= 4 x50= 200 + CFM fan needed

 

[adampolo13]

Oh man! That was way easier than I thought it would be.

Thanks man!

 

[Ziz]

Since the CFM math has already been figured out - fan placement should probably be dictated by your workbench environment. Put it wherever it's convenient to reach your connection out of the workspace (window, most likely) in the shortest distance possible.

 

[hooterville75]

From the research Ive done on spray booths, the fan location depends solely on which type of draft you want weather you want a downdraft or a cross draft. The type of draft you want to obtain is critical to fan location and the amount of CFM's you need.

 

[Elm City Hobbies]

Hey there Adam,

I am sure you have seen pictures of mine, if not here is the link to my Fotki album on it:

http://public.fotki.com/ScottM/models/paint-booth/


Bottom draft, using a 100cfm bathroom fan, and the box is built around a 20" X 16" furnace filter with the front opening being about 18.5" high.

I didn't do any math on mine as far as suction and all of that, just when I bought the bathroom fan I wanted something more than the basic one, but still a reasonable price.

It works fine for extracting paint fumes. 99% of my painting is acrylic, and most of that with Vallejo, so little to no smell already. The odd time I do use an enamel or lacquer, it pulls the overspray out fine, the smell lingers maybe for 10mins or so after....just a matter of leaving the fan on for a bit when you are done.

I like my design, however if I had to do it over again, I would build in lights, instead of the clip on ones....but that is just personal preference. I would also add a couple of clear plexiglass doors so you could close them when done painting....try and cut down on the dust in the booth.

 

[Daf57]

Hey ECH - I'm not seeing the link to the Fotki album pics of your booth - I'd like to see it. I'm working on one myself and could use some DIY ideas! Is it just me or is the link not there?

 

[Elm City Hobbies]

Nah, I just messed up and put the link between IMG tags instead of URL tags.

Should work now.

 

[adampolo13]

Hey Scott, thanks for the pictures! Consider your design officially stolen!!! Haha. I want to do something very similar to that. But as you suggested I am going to add a light to the top and a plexiglass door. I am going to do some more research of fan etc but it looks like there are some pretty good deals at Home Cheapo.

 

[Ravhin]

This is mine http://theironkeep.wordpress.com/2008/05/15/diy-spray-booth/#more-118 . The cover is awesome to use as a nice place where to leave the parts to dry

I have since "upgraded" it with lateral fill lights, the main lighting is still a couple of nice and bright daylight balanced bulbs over the top.

The fan is a kitchen exhaust 300cfm fan. Sucks every bit of over spray and fumes. After I finish painting I leave it running for a few minutes and I'll be left with a perfectly clean and nicely smelling room ;D

 

[Daf57]

I like that Scott - nice and simple since my wood working skills are lacking. One question tho - I think I have the same fan - how did you attach it to the base of the booth? Mine has some push out tabs but it obviously meant for a face-first installation.

 

[Grendels]

Here is the link to the booth I made:

http://www.scalemodeladdict.com/index.php/topic,1361.0.html

In that thread was a discussion about CFM and how to calculate it:

How do you calculate the fan cfm from size? Is there same kind of a ratio to use there?

We calculate the required CFM (volume of air) by taking the area of the capture surface in sq.feet and multiply that by the desired airflow in LFM (speed of air), 50LFM for downdraft, 100LFM for cross draft.

So for Elm's booth: [(16x20)/144]*50 = 111 cfm minimum required for proper air velocity
For Grendel's: [(25x25)/144]*50 = 217 cfm minimum required for proper air velocity
(both downdraft designs)

 

[adampolo13]

Thanks a bunch guys!!! I really do appreciate all the help! Hopefully this weekend I can get around to building the booth.

 

[Elm City Hobbies]

I like that Scott - nice and simple since my wood working skills are lacking. One question tho - I think I have the same fan - how did you attach it to the base of the booth? Mine has some push out tabs but it obviously meant for a face-first installation.

Good question, been a few years since I built this (few....probably more like 7 or more). However if I remember correctly, I pre drilled some holes and bolted it to the bottom of the booth.

 

[adampolo13]

Perfect! Now all I have to do is figure out which regulator/moisture trap to purchase. I have been running without one. I have an el-cheapo harbor freight air compressor which has been great but right before my move I realized that regulator on the tank isn't very good and I cannot control the airflow at any PSI under 20. Opps...

Haha.