Spray booth wet filtration

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PostPosted: Wed Jan 12, 2022 2:41 am
Gents

Looking at options to help pull solvent vapour out of my exhaust air and I saw this old post on a forum which got me intrigued:

"I set up my booth in my garage with a blow thru set up using electrostatic filters on inlet side right after the fan and a set of swamp cooler mats over a pan with an outlet in the outlet duct I then added a water spray bar powered by a small pump. before this setup when I would start painting a cloud could be seen floating down the street when I was painting but after the water spray i could stand in the discharge and not even smell the paint. the water also kills the cyanide in the activator."

I have no experience with evaporative cooler pads but how would this work as if good airflow speed was maintained wouldn't the exhaust air going through these cooler matts just pick up the water and blow out a mist potentially laced with overspray / solvent vapour - not sure if this is any better than the vapour just evaporating? Would I need some kind of baffle exhaust after the cooler pad to grab the mist.

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PostPosted: Wed Jan 12, 2022 9:21 am
So these were called "waterfall booths" here in the US. I am only familiar with them from the furniture manufacturing side of things here. The last industrial model I saw of one of these looked like a conventional paint booth from the inside however the normal air filter arrestor pads at the end/exit part of the booth did indeed have the pads continuously wet. The pads were being sprayed inside by ultra fine water misters with all the water being collected by a large wide trough underneat the bottom most row of pads. This pan was at a slight angle dumping into a 20 gallon or so tank which the owner showed me was behind the pads. That tank use a toilet style float that would allow the level to rise then pump the water to an external filtering system. He said they would check for any larger particles floating on the surface of that trough and skim it at the end of the day. The water coming out of the filter system would go up to a supply tank which would go to the misters again. There was also some type of regulating top up valve in the system as well... And yes, you could go to the termination point of this system and smell nothing.
Again, please note this was a furniture grade operation that I am talking about. I never saw an auto version of one of these booths.
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PostPosted: Wed Jan 12, 2022 4:18 pm
Yes. They're called water wash booths and the filtration is very good. I don't know that they would remove isocyanates unless fitted with an active carbon filter as well.

I have been considering it as a system for my new shop. In my case a particle filter first, then evaporative cooler pads with the fan downstream.
Chris

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PostPosted: Wed Jan 12, 2022 4:59 pm
Ohh, and Chris just reminded me. That booth I was talking about had an optional provision for a carbon filter to handle isocyanates if that is what you were shooting. The particular one I saw wasn't using that because they were just shooting old style nitro furnitue lacquers.
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