surface air leakage
surface air leakage
[′sər·fəs ′er ‚lē·kij] (mining engineering)
The amount of surface air entering the fan through the casing at the top of the upcast shaft, the air-lock doors, and fan-drift walls.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.