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Dust collection CFM ratings are a total scam in most shops
Was setting up my new shop last weekend and actually tested my dust collector with a cheap anemometer. Turns out my fancy 1500 CFM unit is barely pushing 400 CFM once you hook up a 10 foot hose and a blast gate. Found a spreadsheet online from some guy in Oregon who tested 30 different setups, and basically every single hood rating is pure marketing. The real numbers are way lower once you add any resistance at all. Has anyone else actually measured what their system really moves?
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bennett.noah1mo ago
Same thing happened to me when I got serious about my dust collection. I bought a cheap manometer and found my 2HP unit was lucky to pull 350 CFM at the tool. Switched to a shorter hose and dropped the smaller fittings and it jumped up to almost 600 CFM. Real world numbers are just way lower than the fancy stickers claim.
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grantadams1mo ago
@bennett.noah hitting the nail on the head about hose length. Thing nobody talks about is how many people run ductwork with way too many 90 degree elbows. Each one of those is like adding another ten feet of hose in resistance. I measured mine at the blast gate and then again after a couple sharp bends and lost damn near half what I had left. Folks design this stuff like they're running water lines instead of moving air with a vacuum.
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laura_wright1d ago
Oh wow I actually read a really good article that broke this down with some kind of airflow visualizer tool, and it was wild seeing how much static pressure drops with each little bend! It makes total sense though, air is way more finicky than water and that friction adds up fast in a system that's already fighting to pull everything through. Definitely makes me want to grab a cheap meter and check my own runs now.
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