What current should controlled ventilation maintain across the cross-sectional area?

Controlled ventilation in mining operations is crucial for ensuring that air flow is adequate for both safety and operational efficiency. The recommended air velocity across the cross-sectional area of a mine's ventilation system is particularly important for the dilution of harmful gases, the removal of dust, and the overall quality of breathable air for miners.

The appropriate current for controlled ventilation is established based on guidelines and safety standards, which indicate that a velocity of 0.3 meters per second is typically sufficient to ensure effective air movement without causing excessive turbulence or energy loss. This speed facilitates a balance between providing adequate fresh air and maintaining comfort levels for workers.

In contrast, other velocities listed, such as 0.1 m/s, may be too low to ensure proper ventilation, while 0.4 m/s and 0.5 m/s could lead to unnecessary energy expenditures and discomfort due to excessive airflow. Therefore, 0.3 m/s correctly reflects the standard practice for maintaining optimal ventilation conditions in mining environments. This reflects the need for sufficient airflow to dilute gases and remove particulates without creating an unpleasant working atmosphere.