Measure the circumference of the rollers in the conveyor , calculate revolutions per minute and then multiply these two figures together to determine conveyor belt speed. Manufacturers and grocery stores typically use conveyors to move products along a specific path. Objects and materials placed on top of the conveyor belt will be moved from one edge to the other as the rollers spin. The speed at which the conveyor belt moves depends on the size of the rollers and their revolutions per minute.
Measure the diameter of the rollers around which the conveyor belt is wrapped.
Multiply the diameter of the roller by pi, 3.14159. This calculation yields the circumference of the rollers. Every time the roller spins one revolution, the conveyor is moved a linear distance equivalent to the circumference of the roller. Pi is a dimensionless factor, meaning it does not matter whether inches, centimeters or any other units of measurement are used.
Measure the revolutions per minute of the rollers. Count how many full rotations are made by the roller in one minute.
Multiply the RPM by the circumference of the roller. This calculation provides the linear distance traversed by a point on the conveyor belt in one minute.
Calculate the distance traveled for one hour. For example, a roller with a diameter of 2 inches, has a circumference of 2 x 3.14159 or 6.28 inches. Multiply that figure by the number of revolutions, in this example, 10 to arrive at a total of 62.8 inches traveled per minute. Multiply one more time by 60 to arrive at the total inches traveled per hour which equals 3,768. Next, divide by 12 to arrive at 314 feet, then divide by 5,280, to convert to miles per hour, 12 inches = 1 foot and 5,280 feet = 1 mile. In this example, the conveyor runs at approximately 0.05947 MPH.
TL;DR (Too Long; Didn't Read)
Distance traveled, or displacement, per a change in time is the definition of velocity, or speed and direction.
When making measurements, keep fingers away from the rollers. They can pull your fingers in quickly and smash them between the conveyor belt, causing severe injury.