Grinding wheels on floor stands, pedestals, benches, and special-purpose grinding machines and abrasive cutting-off wheels shall have not less than the minimum exhaust volumes shown in Table G-4 with a recommended minimum duct velocity of 4,500 feet per minute in the branch and 3,500 feet per minute in the main. The entry losses from all hoods except the vertical-spindle disc grinder hood, shall equal 0.65 velocity pressure for a straight takeoff and 0.45 velocity pressure for a tapered takeoff. The entry loss for the vertical-spindle disc grinder hood is shown in figure G-1 (following 1910.94(b)).

         TABLE G-4 - GRINDING AND ABRASIVE CUTTING-OFF WHEELS
________________________________________________________________
                 |                      |
 Wheel diameter  | Wheel width (inches) |    Minimum exhaust
      (inches)   |                      | volume (feet (3)/min.)
_________________|______________________|_______________________
                 |                      |
To 9.............|               1 1/2  |            220
Over 9 to 16.....|                   2  |            390
Over 16 to 19....|                   3  |            500
Over 19 to 24....|                   4  |            610
Over 24 to 30....|                   5  |            880
Over 30 to 36....|                   6  |          1,200
_________________|______________________|_______________________

For any wheel wider than wheel diameters shown in Table G-4, increase the exhaust volume by the ratio of the new width to the width shown.

Example:
 If wheel width = 4 1/2  inches, then

        4.5 divided by 4 X 610 = 686 (rounded to 690).

Information last verified March 13, 2013