I’ve been doing some calculations and running large evac ducts outside (40-ish feet) from the booth isn’t going make any (financial) sense. So a change in direction - I need to figure out how to filter the air we’ll enough that I can breathe it and vent the hood inside. These home air filters ain’t good enough for that.
Not sure why I didn’t do it sooner but I started looking at smaller PC booths another the market to see how they set up the exhaust. Here’s a booth that Eastwood sells which design-wise is like most of what I found.
I can do something like this but with my space constraints, I’ll need to vent out the top instead of to the rear.
I found this cool site called PowderCoatingOnline-
https://www.powdercoatingonline.com/the-super-specials-showcases/ . It has a listing of a bunch of different distributors and manufacturers for everything powder coating. . I started calling through the list until I found a supplier that both builds booths and sells filters. I landed on
http://www.powdermarket.com. A Short conversation with these guys was beyond enlightening. Not only were they happy to answer my questions, they also made some design recommendations (along with some education) for my booth filtration and design.
First - my fan must pull 100 cfm per square foot of booth face/opening. That was helpful. My opening is 50”h x 38.5w so I’ll need a fan that’s ~ 1350cfm.
Second - in order to recirculated the air back into the room, they recommend using a 3-stage filter assembly just like they do on their coating booths. Each and a specific purpose and together they keep the consumable cost low yet yield breathable exhaust air.
Stage 1/. Called a blanket filter, it looks an awesome lot like insulation. It is sold by the roll and you cut it to size. In the size I’ll be needing (25-ish x 25-ish), the math ends up ~$8 per fikter. In a 40hrs/week setting, they last about 2 weeks.
Second stage is a wind sock looking filter that’s called a pocket filter @ ~$130. Typical production usage @ 40/week they last about a month or so.
Third stage is a hepa filter which looks like a traditional filter but on steroids. They cost ~ $250 each and last ~ 3 months in a 40/week environment.
I will not be coating 40 hours per week, probably more like 4 hours per month...so filters should last me WAY longer. PowderMarket sells a slick little vacuum gauge (a Manometer) that can help tell you when the filters need to be addressed. It has two pickup tubes which you can place on either side of a filter to understand what airflow loss you have. Initial readings are used as the baseline and then once you get to ~ 50% reduction in efficiency, you change the filter.
Though you could install one on either side of all three filters and know exactly when to change each, I think I’ll only put one with the front side pickup somewhere in front of all filters and then after the second stage.
Filters inbound.