Understanding Performance Metrics and Challenges
Bulk materials handling is a continuous process, which means that performance measurements often manifest as data points on a statistical process control chart rather than absolute values. When controlling fugitive materials such as dust collection or belt cleaning, the outcomes typically form a classical bell curve. This implies that at times, results exceed the average, while at other times, they fall below it. Achieving 100 percent removal of dust or carryback is highly unlikely without significant cost or unintended consequences, such as damaging the belt's top cover through aggressive scraping. 
As the management of fugitive materials is an ongoing endeavor, gathering more data points enhances the accuracy of results. Hence, it's advisable to assess performance across all conveyors rather than relying on just one to evaluate a plant's effectiveness in reducing dust and spillage.
Similarly, referring to efficiency as a universal value regardless of conveyor condition or bulk material properties is misleading. Efficiency depends on specific factors such as the condition of equipment and the nature of the bulk material, not solely on the design of the belt cleaner. For instance, a belt cleaner rated at 90 percent efficiency in removing carryback may leave behind layers that vary greatly in thickness—ranging from 100 millimeters (4 inches) to just 1 millimeter (0.04 inches). While both scenarios achieve 90 percent effectiveness, the associated costs and operational challenges differ significantly. Therefore, prioritizing a cleaner that consistently reduces carryback to a thickness of 0.1 millimeter (0.004 inches) would yield better outcomes compared to simply aiming for a generalized 90 percent efficiency benchmark.
Due to the multitude of variables involved in handling bulk materials—spanning from the materials themselves to conveyor conditions—it is unfeasible to completely eliminate fugitive emissions over extended periods. In practical operations, satisfactory belt-cleaning performance often entails maintaining fugitive material at a level necessitating weekly cleaning, without compromising safety or productivity.