Exhaust Stack & FPM

Typical Exhaust Stack Configurations Exhaust stacks are required to ventilate the booth to the outside.

  1. Stacks should be the same size and diameter as the fan.
  2. The stack should discharge vertically for adequate exhaust air flow.
  3. It is recommended that the stack extend a minimum of 6′ above the roofline or as required by local codes.

The fan installed in the stack outside of the building, is the preferred configuration. Not only is the fan easy to reach for servicing, but the noise generated by the fan’s RPM and the air velocity produced are kept outside of the working zone.

A stack section with “cleanout door” is installed directly below the fan to permit access to it for cleaning, servicing or replacement. This configuration places the exhaust fan inside the building. This can be a more costly solution because of the special muffler duct required to suppress sound the fan and air velocity will generate in the working zone. The stack section with cleanout door is still in place next to the fan, and the special muffler stack section is directly below that.

FPM Specification for Various Applications


Based on empty booth-Velocity FPM Equipment / Application:

  • 50-100 Automotive refinish
  • 100-125 Hand electrostatic – batch operation
  • 100-125 Hand spray – batch operation
  • 80-100 Automatic electrostatic – conveyor system
  • 125-150 Hand spray conveyor system up to 10 FPM – small parts
  • 125-150 Hand spray conveyor system up to 20 FPM – small parts
  • 150 Hand spray – large parts
  • 150-175 Automatic, air-atomized / airless


Based on Empty Booth-Velocity FPM Equipment / Application

  • 35-60 Automotive refinish
  • 125 Side walls, pressurized – large objects only
  • 125-150 Side walls, pressurized – large and small objects
  • 150 Side walls, unpressurized
  • 300-500 At grating, no side walls (velocity at breathing zone will be poor)