Direct Answer: To calculate the required vacuum airflow in cubic feet per minute (CFM) for dry concrete cutting diamond blades and tuckpointing grinders under OSHA 29 CFR 1926.1153, multiply the blade outer diameter in inches by 25 CFM: CFM = Blade Diameter (Inches) x 25. For example, a 7-inch tuckpointing grinder blade requires a HEPA vacuum providing at least 175 CFM (7 x 25 = 175 CFM), while a 14-inch handheld cut-off saw requires at least 350 CFM.
OSHA Table 1 specifies that when dry cutting masonry or tuckpointing mortar with handheld grinders and saws, local exhaust ventilation (LEV) vacuums must provide sufficient capture velocity to prevent dust escape at the shroud edge.
Required Airflow (CFM) = Blade Outer Diameter (Inches) x 25 CFM.