how to check air velocity in feet per minute
The old standard was 100 linear feet per minute (lfm), and this is still stated in the International Fire Code (IFC). This air velocity is calculated with the spray paint booth empty and using a cross-sectional area of the air flow direction. The more current codes require a minimum of 4 air exchanges per minute for wet or solvent-based paints. Powdercoat booths are required to have 60 lfm.