We bought our old 9x9x9 Spray booth 20 years ago and it was probably 20 years old at that point so nobody really has any data on this old thing.

We're trying to get an idea how many CFM it pulls, because we're dealing with a lot of negative pressure issues in our building in the winter with all the rollup doors closed. In the process we need to get an estimate of how many CFM we're pulling out.

I know this depends entirely on the pulley, ducting, and filter media. I've looked around and most of these fans with a 2hp motor pull at most around 6K CFM, does that sound about right to y'all?

easy, height x the width x 100 ft per min equals cfm

the older booths especially binks and devilbiss spec'd their booths at 125 fpm face opening.

for example if your booth is 8 wide x 7 high mini\mum it is pulling is 56 sq ft x 100 fpm = 5600 cfm. unless you have a downdraft this is the formula to use.

best thing you can do to minimize cfm loss is get a vfd for your fan motor especially with and if your using air assisted airless. vfd are dirt cheap and work like a rheostat for your house lights.

try a vfd you will like it and it will save you heat and ac costs

good luck
herb j

Thank you for that help there. And you're right about the VFD, they are very helpful.

However, the issue is more complicated than just that. We have a flatline sprayer, this 9x9 spray booth, one large dust blowoff fan (5ft dia), and a 20hp externally mounted dust collector. We're trying to tab up how much CFM we're pulling out of this building, and I cannot really put a controller on those, they all need to run wide open just based on experience here.

digital meter

digital meter

https://trutechtools.com/DAFM3B