Where must all main fans be installed?

The proper location for installing all main fans is on the surface. This position is crucial for ensuring effective ventilation throughout the underground mine. When fans are placed on the surface, they can draw fresh air down into the mine while expelling stale air, thus maintaining a suitable atmosphere for the workers below.

Placing main fans on the surface allows for easier maintenance and inspection, as well as better access to the fan systems. Surface installation also minimizes risks associated with underground electrical systems and allows for larger, more powerful fans that can handle higher volumes of air, essential for meeting ventilation requirements.

Overall, the surface location optimizes air circulation, enhances safety, and supports operational efficiency in underground mining operations.