What is the term for the sharp dip in the fan curve that indicates wasteful power use and potential fan damage?

The term that accurately describes the sharp dip in the fan curve, which signifies wasteful power use and the risk of fan damage, is known as the "stall trough." In fan performance analysis, a stall trough indicates that the operating point of the fan is located within a range where airflow is unstable. This instability can lead to reduced efficiency and increased power consumption, as the fan struggles to maintain the required flow rate. Additionally, operating in this zone may cause mechanical stress on the fan components, potentially resulting in damage over time.

Understanding the concept of the stall trough is crucial for optimizing fan operation and ensuring safety in mine ventilation systems. It helps engineers and operators make informed decisions about the selection and adjustment of fans to avoid operating in this detrimental range, thus improving overall system performance and longevity.