Figure 2. Spatial ventilation plan of the seam 510D at the level 660 of the colliery W

Station No. 1. The tracer gas arrived at the station at 900 o’clock. At that time the concentration of the gas amounted to 0,3 ppb. That concentration changed only very slightly for the next two hours. Then its concentration increased up to the value of 11,9 ppb, which was most probably caused by disturbances in the ventilation network resulting from a stop of the main fan at the southern ventilation shaft. The disturbances occurred between 1040 and 1050 o’clock. At the later sampling times tracer-gas concentrations were near zero.