The natural method of ventilation for tunneling is conveniently used when:
A. A drift is not driven from portal to portal
B. Diameter of the tunnel is large but its length is small
C. Tunnel is not to be laid in the direction of wind
D. Blowing and exhausting is not done
Answer:B
The natural method of ventilation for tunneling is conveniently used when:
A. A drift is not driven from portal to portal B. Diameter of the tunnel is large but its length is small C. Tunnel is not to be laid in the direction of wind D. Blowing and exhausting is not done