Rice Lake BCi Belt Scale - Installation and Operation Manual Version 2.03 - Manual (Page 14)

8 Installation and Operation Manual
1.3 Application Brief
There are four factors used to determine a suitable belt scale application on a given conveyor.
• Load cell size
• Belt speed
• Idler spacing
• Belt splicing
1.3.1 Load Cell Size
The capacity of the belt scale is rated on the maximum continuous load that can be carried across the weigh idler.
The capacity of the conveyor should be known prior to determining the components of the scale system. The load
cells should be sized to operate across a loading range with a marginal safety factor. The minimum net loading
should be greater than 10% of the rated capacity and the maximum loading should be less than 65%. The load
applied to the loadcell can be calculated with the following formula:
Net load = (conveyor capacity / belt speed) x idler spacing
Gross load = net load + (idler weight + belt weight + mounting hardware)
Examples:
Net load = (50,000 lbs per minute / 400 feet per minute) x 4 foot spacing
Net load = (125 lbs per foot) x 4 foot spacing
Net Load = 500 lbs.
Gross load = 500 lbs + (175 lb idler + 48 lb belt + 24 lbs hardware)
Gross Load = 747 lbs.
Net Load > 10% of total load cell capacity
(4) x 500 lb load cells x 10% = 200 lb 500 lb > 200 lb (500 lb load cells are okay)
(4) x 1000 lb load cells x 10% = 400 lb 500 lb > 400 lb (500 lb load cells are okay)
(4) x 2000 lb load cells x 10% = 800 lb 500 lb > 800 lb (2000 lb load cells are too large)
Gross Load < 65% of total load cell capacity
(4) x 250 lb load cells x 65% = 650 lb 747 lb > 650 lb (250 lb load cells are too small)
(4) x 500 lb load cells x 65% = 1300 lb 747 lb < 1300 lb (500 lb load cells are okay)
(4) x 1000 lb load cells x 65% = 2600 lb 747 lb < 2600 lb (1000 lb load cells are okay)
The example listed would require 500 lb or 1000 lb load cells.
1.3.2 Belt Speed
The belt speed is defined as the maximum velocity of the unloaded conveyor belt. The belt speed can be variable,
but for sizing requirements the maximum speed is required.