Drilling And Blasting - Study Mode
[#181] The coal dust, when suspended in air, is capable of bursting into . . . . . . . . explosion and propagate it.
Correct Answer
(C) Coal dust
[#182] Rate of penetration of compressed air drills varies from . . . . . . . . in hard rocks in m/min.
Correct Answer
(B) 0.2 - 0.3
[#183] Once the coal dust explosion starts, its propagation needs very small quantity of dust, only 1 gram per c.c of space which is equal to thickness of a layer of ordinary thick paper over a periphery of . . . . . . . .m road way.
Correct Answer
(B) 2.4 m × 2.7 m
[#184] An evasee is used in exhaustive ventilation is
Correct Answer
(C) Recover velocity head lost to atmosphere
[#185] In reversal of air screw fan the quantity of air reduce to nearly . . . . . . . . on reversal.
Correct Answer
(D) 40%