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1965 2+2 Vintage Burgundy A-code C4
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I say wire it up with whatever speed control you can and try it out. Slow it down or speed it up if you see the spray hanging around too much or getting sucked sideways coming out of the fun. I’ll start boxing up test pieces for retouch today practice on😉
 

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I could be mistaken but I looking back at your posts @Turnall , isn't the depth of your booth 24 feet? If that's the case from the reading I've been doing on the topic, you want to use the width and height of the booth for your calculations.

Using the numbers from here:
PAINT BOOTH AIR FLOW: HOW IT WORKS : Paint-Booths.com

On cross flow, semi down draft or open face, use
15' width x 8' height x 100 = 12000 cfm

On side down draft
15' width x 8' height x 40 = 4800 cfm

Looking at your photos and numbers, I'm making the assumption the height will be around 8' from your cubic feet of 2880.

As for exchanges per minute, 12000/2880 = 4.2 or 4800/2880 = 1.7 changes per minute, depending on the type of booth you end up with.

I think the way you calculated it would be correct if you had the entire ceiling outfitted with filters, creating a true down draft booth, so I'm guessing it's more of a semi-down draft? If that's the case, I'd go with something closer to the 12,000 cfm number.
 

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I could be mistaken but I looking back at your posts @Turnall , isn't the depth of your booth 24 feet? If that's the case from the reading I've been doing on the topic, you want to use the width and height of the booth for your calculations.

Using the numbers from here:
PAINT BOOTH AIR FLOW: HOW IT WORKS : Paint-Booths.com

On cross flow, semi down draft or open face, use
15' width x 8' height x 100 = 12000 cfm

On side down draft
15' width x 8' height x 40 = 4800 cfm

Looking at your photos and numbers, I'm making the assumption the height will be around 8' from your cubic feet of 2880.

As for exchanges per minute, 12000/2880 = 4.2 or 4800/2880 = 1.7 changes per minute, depending on the type of booth you end up with.

I think the way you calculated it would be correct if you had the entire ceiling outfitted with filters, creating a true down draft booth, so I'm guessing it's more of a semi-down draft? If that's the case, I'd go with something closer to the 12,000 cfm number.
You are correct on your assumption, 8' ceiling height.

What I'm stuck on (and thanks for the number crunch) is what my existing fan will move CFM wise versus what the calculations say I need. From what I've found my "design" will be a semi downdraft, so I'm good with the 12,000 CFM number, I just need to translate that into what my 48" blade fan will need to rotate at to give me the desired movement.

Yeah, probably overthinking it, but there's an answer to the question...

Allen
 

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That's a helpful sketch - I thought you were using BOTH fans! LOL

Ok, so do you have any information on the fan, like brand and part number? There are lot more variables than diameter; such as, number of blades, blade pitch, and even how tight the fan is to the housing.
I'm going to the warehouse so I will get that information. It's a 6 blade fan. I'm not going to know the blade pitch but will research and see if i can determine what it is.

Allen

767065
 

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I'm going to the warehouse so I will get that information. It's a 6 blade fan. I'm not going to know the blade pitch but will research and see if i can determine what it is.

Allen

View attachment 767065
Looks like it's in good shape, so hopefully it'll have model number still listed on it. Also, you'll need the size of that pulley to get motor speed required.

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If I"m looking at this correctly and you are pulling the air into the booth from floor level and exhausting it from the top. that's updraft and much less bueno for painting. If it is pulling air from down low in a chute and then exhausting up through the fan, then that IS downdraft, provided you have enough inlets up high and either opposite the exhaust or spaced accordingly, so that you get full exchange. Might just be misreading the drawing....
View attachment 767061

Just drawing what I'm planning to do. That will be a 2' deep mixing table and it will be enclosed except at the bottom which will be open to hopefully help draw air along the whole floor.

Allen
 

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Yes, so you are building a plenum down to a floor intake? That should work well if you can figure the flow. Isolating the motor is key, as mentioned. Wouldn’t want to lay down nice paint just blow it up.
 
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I'm going to the warehouse so I will get that information. It's a 6 blade fan. I'm not going to know the blade pitch but will research and see if i can determine what it is.

Allen

View attachment 767065
Too bad there's no info on it. Nothing on the second fan either?

What's the diameter?

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Yes, so you are building a plenum down to a floor intake? That should work well if you can figure the flow. Isolating the motor is key, as mentioned. Wouldn’t want to lay down nice paint just blow it up.
Correct.

I'll probably use a gas pump motor on it... ;)

Allen
 

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Some of those big fans move up to 21,000. Build it, get you a meter and measure flow, adjust from there with speed control, dampers, pulley size, etc.
 

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"I am running a commercial booth it has a Very large air box 18'x9'x2' my fan is a 30" three bladed fan with blades shaped like actual aircraft propeller its belt driven with 5 hp 3 phase explosion proof 1750 rpm motor cant tell you pulley sizes or amount of air it actually moves sorry, Im running 10 intake and 10 exhaust filters 20''x20'' paint booth area 14'x24'x 9'
I have absolutely no windy spots and am unable to tell there is an air exchange going on till you see the over spay moving on out while spraying. "

I found this on AutoBody101. Pretty close to the size I'm doing...

Allen
 
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