Drilling And Blasting - Study Mode
[#76] Number of shelves in heavy weight barrier.
Correct Answer
(C) 16
[#77] CO/O 2 deficiency ratio is . . . . . . . . normal to coal mine.
Correct Answer
(A) 0.1 to 0.5%
[#78] Quantity of air at the working face can be increased by introducing.
Correct Answer
(C) Compressed air jets
[#79] When O 2 falls to 5% or less and methane rises to 30% N more behind the stopping, the samples collected at intervals of . . . . . . . .
Correct Answer
(A) 48 hours
[#80] The explosives commonly used in solid blasting.
Correct Answer
P 1 explosives