Which of the following is NOT a condition that would call for more air volume in hard rock drilling?

• A. Shallow holes
• B. Deeper holes
• C. Larger hole diameter
• D. Increased cuttings in hard or fractured rock

Answer: (A)

Air volume is increased to keep cuttings moving to surface, cool the bit, and prevent stalling. When you drill deeper, cuttings must be lifted farther and more heat is generated, so more air is needed. A larger hole diameter means the air has to move through a bigger space, which can reduce flushing efficiency unless you increase flow to maintain the same carrying capability. Hard or fractured rock generates more cuttings and they’re tougher to lift, so more air is required to clear them. Shallow holes, however, have a short path to the surface and typically produce fewer cuttings, so they don’t require the extra air volume. Therefore, shallow holes are not a condition that would call for more air volume.