Air velocity in ventilation systems
an air velocity meter to measure the speed of ventilating air in mine shafts
existing duct = velometer (Google velometer). Calculate velocity if volume is known and the size of duct volume (cubic feet) multiplied, square feet feet of duct, IE. 1000 cubic foot of air * 12" x12" square duct = 1000 cubic feet * 1sq. foot = 1000 feet per minute