Riley

I have a old furnace fan to pull the air out of the garage. The wall are hung with plastic and i have another smaller fan with filter to allow air in.The ? is, The exhaust fan motor is with the fumes. Is this enough of an ignition source, better to ask now than later.thanks

Big Fish

If your furnace blower has a direct drive (no belt) motor, it is a shaded pole or permanent split capacitor motor and will not generate a spark while starting or running (unless it shorts out and burns up). If the blower has a belt drive setup it will use a split phase motor which has a starting switch that will generate a spark on startup. In either case in order to get ignition, the mix of air to paint fumes would have to be very close to 10:1. Anything more or less will not sustain combustion or ignition. Safest bet would be to use the belt drive setup and provide some type of ducting so the motor will be out of the combustible airflow, or use explosion proof motors, lighting, switch gear, etc (big bucks).

zwede

Sounds like the setup you have will create a low pressure in the garage which will make dust and dirt get sucked in through every gap. I would set it up the opposite. Switch your big fan to blow air into the paint area (with a filter), and no fan to exhaust, just an opening for air to leave. This way the garage is positive pressure and no dirt gets sucked in. This also lessens (or eliminates) the chance of an explosion as the air going through the fan will be outside air.

73ragtop

Sounds like a good idea to prevent explosions, but if the pressure differential is great enough, would the air velocity be high enough to cause problems with a typical HVLP spray pattern? You might get a really interesting custom effect in your paint job. :lol:

sb69coupe

:iagree: with Markus. Positive pressure will result in a much cleaner home spray booth. Use your fan to "push" air through a pair of furnace filters, and direct the input air away from the area where you'll be spraying. This will help prevent the dust from creeping in through the gaps.