press-in fan

A press-in fan (industry-preferred term: forcing fan) supplies clean air under positive pressure to underground workings via ventilation ducts. Its role is to deliver the specified quantity at the working face despite cumulative pressure losses from duct length, bends, leakage, and ancillary equipment. By maintaining a surplus of intake air locally, the arrangement improves gas dilution, reduces fume exposure after blasting, and limits dust carry-over to adjacent headings.

Press-in systems are widely used for development headings, shaft stations, refuge areas under construction, and equipment bays. Selection begins with the design duty: airflow at the face and total pressure across the duct string. The fan characteristic should intersect the system curve near peak efficiency to minimize power. Where explosive atmospheres may occur, certified explosion-proof motors and enclosures are specified together with compliant terminations, anti-static ducting, and appropriate monitoring.

Typical features include aerodynamic inlet collectors, high-efficiency axial impellers, and variable-frequency drives for staged ramp-up as headings advance. Sound attenuation may be added near occupied zones. Proper installation—tight joints, smooth transitions, and tensioned hangers—preserves pressure and reduces recirculation risk.

• Function: press-in supply to faces/roadways
• Benefits: better gas dilution, cooling, and visibility
• Configuration: axial or contra-rotating, VFD control, silencers