Precautions when spraying Poly fiber products??

[avidflyer]

I've painted 3 or 4 airplanes with the poly fiber system (not aerothane) I do it in a 16' x24' garage stall. Have a window on one end that I put 4 layers of pourus cloth over to act as a filter, and raise the garage door on the other end up high enough to put a 20" box fan under the door. Close off the sides with plywood. The air goes through well enough that you never see a mist in the air, and I think the concentration of solvents is eliminated by that much air going through. Never had a problem blowing my self up (yet), but you can hardly notice the fumes when you run the fan steady. I do wear a good resperator, but not a fresh air system. JImChuk

[Danzer1]

Where do find a fan with a sealed motor?

Eddie, Thats hard to do. You can sometimes find an HVAC guy with a used belt driven squirrel cage blower where the motor is mounted outside of the blower housing. Mount the assembly outside the enclosure and suck the air out.

Fully protect those eyes!

Greg

[efwd]

Thanks Greg.
Jim, thanks, I can do that.

[Av8r3400]

As Jim said, put the fan on the intake side of the system so it's forcing only fresh air in, put filters (cheap furnace filter work well) on the exhaust air leaving the "booth".

[avidflyer]

Sorry Larry, I have it set up the opposite way. Air comes in the window with the filter over it, goes out through the fan under the door. After a while I've seen paint stuck to the fan blades, but the air stays clean in the paint booth. If the overspray and evaporating solvent is diluted enough, there is no danger of explosion. Of course then the question is: how much is enough? :-) JImChuk

[Danzer1]

As Jim said, put the fan on the intake side of the system so it's forcing only fresh air in, put filters (cheap furnace filter work well) on the exhaust air leaving the "booth".

Larry, Have you had your 1st cup of coffee yet this morning?

I don't think that's what Jim meant and it is not recommended.

All professional paint booths now are negative pressure, most downflow but that's not practical for a home booth. You don't want to "push" outside particulants into your wet paint. There is no need to filter the exhaust air unless you are trying to be nice to your neighbors. In fact the paint particulants will clog the filters enough so you don't have enough airflow.

Fan on the exit and filter the air coming in. Cost is the same either way, so? 20 year retired commercial HVAC engineer - I've designed a few custom booths.

FWIW, Greg

[southwind32]

I know lots of garage painters have used store bought box fans for exhausting the air. Are they safe? I haven't heard of any of them causing an explosion, but that doesn't mean they are totally safe...........so what fan is safe to use and where do you buy one...........again, for a garage painter that doesn't cost a bunch.
Thanks
Brian

[jrevens]

I did what painting I needed to do on my Kitfox outside on my driveway, and it shows it. When painting my T-18 I built a booth in my garage. Used a row of several furnace filters taped together and brought the door down to their height, using cardboard to fill the openings to the sides of the filters. I got a nice big, cheap box fan to install in the walk-in door opening to suck the air out. I put a layer of filter material in front of the fan to slow down the accumulation of paint on it, and changed that when necessary but the fan still got a lot of paint on it. If you can get a fan with a simple shaded-pole motor instead of split-phase or PSC, there will be no start windings and no switch on the motor itself to cause a possible spark. Even if the motor does have a centrifugal starting switch or a relay, the switching should only occur during the motor starting phase, when you’re not painting yet. There should be no other source of sparks from the motor itself unless it failed and “smoked”. You’ll still have an on-off switch, but you’ll operate that when you’re not painting. Regardless of the type of fan motor, the chance of explosion is very slim... I’ve never heard of it happening personally, but that doesn’t mean it couldn’t. If the fan is running before and after painting, the level of fumes in the inclosure should be low enough to prevent that also. Where you’d possibly increase your chance of getting in trouble is if you had someone turn the fan on after you started, with a heavy mist in the air and the on-off switch making a little spark. Sorry for the long-winded explanation, but the bottom line is that an explosion-proof motor is probably not needed, and common box fans have been used for this purpose by many, many people. However, proceed at your own risk.

[Av8r3400]

I have set up box fans using both methods in temporary paint booths. Sucking or blowing. Using it to evacuate the fumes is more efficient and works better, but if there is fear of explosion, blowing in fresh air is an option. Cheap furnace filters, even several stacked up, will mitigate much of the particulates.

Putting a $10 Walmart fan on both intake and exhaust works too.