Optimizing Skirtboard Length for Efficient Conveyor Operations and Dust Control
Skirtboard length refers to the extra length of steel wall beyond the impact zone of a conveyor system. The impact zone is essentially an extension of the loading chute down to the belt.
The skirtboard should extend in the direction of the belt's travel beyond the point where the material load has fully stabilized in its intended profile for the rest of its journey on the conveyor. In cases where the material load never fully stabilizes, such as with very fine materials prone to becoming airborne or materials that tend to shift, or in conveyors with multiple loading points, skirtboards are necessary for the entire conveyor length. Belt feeders, which are typically short and loaded almost to the full width of the belt, commonly require full-length skirtboards.
Determining the minimum length of the skirtboard should consider both the total air movement and the belt speed, guided by these principles: For airflow below 0.5 cubic meters per second, the skirtboard length should be 0.6 meters per 0.5 meters per second of belt speed. For airflow above 0.5 cubic meters per second, it should be 0.9 meters per 0.5 meters per second of belt speed. If airflow is under 1000 cubic feet per minute, the skirtboard length should be 2 feet per 100 feet per minute of belt speed, and for airflow over 1000 cubic feet per minute, it should be 3 feet per 100 feet per minute of belt speed.
To prevent spillage or belt damage, the skirtboard should end above an idler rather than between idlers, which may necessitate a longer skirtboard overall.
Another factor influencing skirtboard length is the need to enclose dust suppression or collection systems. The walls of a dust control enclosure can effectively act as a skirtboard, often providing more length than required solely for load stabilization.
Increasing the skirtboard length incurs additional costs for the maintenance of longer liners and seals, a slight rise in steel costs, and a small increase in conveyor power requirements due to increased friction and sealing strip length. However, these costs are typically outweighed by long-term benefits.
In some cases, such as with belt incline, conveyed product shape, or material bed depth, significantly extending the skirted area may be necessary to prevent material spillage.
When uncertain, it's advisable to opt for a slightly longer skirtboard than the minimum required by the equations above. A 25% increase in settling area length is recommended to enhance dust control with minimal additional power and steel expenses. For conveyors with multiple load zones, calculations should consider total airflow from all loading points to determine the settling zone's minimum dimensions after the last loading point.