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Downdraft Priming Table

rynmss

Member
I saw some plans at one point for a priming table that had a boxed bottom, and a traditional box fan for ventilation, creating a downdraft for overspray.

I can't find the plans anymore, but would have no trouble constructing it from scratch. My question is, are traditional box fans safe with an epoxy-based (Akzo) primer—or does one need explosion proof fans for this?
 
Downdraft paint booth

I used a bildge blower. Intrinsically safe. I put a 4" dryer exhaust in my shop wall. When needed, I used the setup to exhaust fumes outside.
That said, I will do whatever I can to avoid using it. Only when it's too cold to shoot paint outside.
 
closet shelf and furnace fan

I used a 20" closet shelf and a discarded furnace fan.
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I saw some plans at one point for a priming table that had a boxed bottom, and a traditional box fan for ventilation, creating a downdraft for overspray.

I can't find the plans anymore, but would have no trouble constructing it from scratch. My question is, are traditional box fans safe with an epoxy-based (Akzo) primer—or does one need explosion proof fans for this?

It probably should be explosion proof, however the risk of the "mixture" igniting is likely to be low because it is too lean by the time it gets to the fan motor.

The industrial extractor fan that I use is located at the end of a 15' duct, with a filter at the inlet to the duct. This fan is not explicitly labelled as explosion proof but I haven't had any problems with fire.
 
motors

The most important aspect of the motor is
1-It NOT have brushes They cause BOOMS
2- if possible it should not be in the air flow, I.E. a belted squirrel cage system.
3-See if it will work with a rheostat so you can change the air flow.
Vapors do go boom cause, I was blown up by them once a long time ago. Was not motor caused, BUT?????!!!! I don't like going boom.
A friend "Jimmy" blew the back out of his shop once. Guess he was trying to clean the shop at midnight. OH ya to much beer also.
As far as the "mixture" being to thin to explode/ignite. Good luck with that. A spray gun doesn't have any idea what an explosive mixture is.
My three cents worth Art
 
Filter for Downdraft

Just to help keep paint out of the fan, I would use some sort of separation media. I work in an automotive paint shop and you could easily come up with something like what we use. Look at the Wenker Rob at the link below. Their filter is an expanded paper media like what is used for packing material with a denser mat police filter behind it.

https://www.wenker.de/en/products/plant-construction-painting-booths/dry-separation/

As far as explosion proof, make sure the motor is brushless and your electrical connections are outside of the box. No spark, no explosion. What I said above doesn't make it fully intrinsically safe and eliminating the possibility, but for a home application, that's all I would do. The above filtration doesn't eliminate the risk either. It separates the paint so you aren't coating your fan blades, ducts, and/or grass outside. The solvent (which is the flammable part) still exists.
 
Depending on your shop layout, PUSHING air into the building on the far side while painting over the outlet may solve your issues with explosion proof fans etc. For priming (maybe not finish work), any dust carried along would not be a factor.

Just a thought...
 
Thank you all for the suggestions and help. This should make putting together a spray station much easier.
 
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