In a mine ventilation system, the resistances of two splits A and B are 0.5 Ns2m-8 and 2 Ns2m-8 respectively. Combined resistance of two shafts and trunk airways is 0.7 Ns2m-8. A quantity of 20 m3/s of air passes through split A. The total air quantity passing the mine in m3/s is
A fan circulates 24 m3/s of air at a pressure of 1200 Pa in a ventilation district. It is intended to reduce the air quantity to 16 m3/s by placing a regulator. Assuming the pressure remains unchanged, the size of the regulator in m2 is
A mine fan produces 30 m3/s of air at 240 Pa pressure running at 1400 rpm. If the fan speed is increased to 2100 rpm, the pressure in Pa and the quantity in m3/s generated by the fan will be
Air flows at 2 m3/s through a forcing fan duct of 0.3 m2 having uniform cross-section. The duct resistance is 40 Ns2m-8 and air density is 1.2 kg/m3. The total pressure generated by the fan in Pa is
While measuring average air velocity of air flowing through a circular duct using precise traversing with equal area method, the radii r1, r2 and r3, in mm, as shown in the figure of the three circles should be
An exhaust fan attached to an evasee of 18 m2 cross-sectional area at the outlet circulates 150 m3/s of air at the pressure of 1000 Pa in a mine ventilation system. The ratio of the inlet to outlet area of the evasee is 1 : 4 and the density of air is 1.2 kg/m3. The quantity of air circulated in the mine in absence of evasee is 120 m3/s. The eva see efficiency in % is
A fan running at a speed of 280 rpm circulates 105 m3/s of air in a mine. If the power input to the motor for driving the fan is recorded to be 75 kW, with the combined efficiency of fan and motor at 70%. the fan pressure in Pa is
Pressure characteristic of a mine fan is given by. P = -0.06Q2 + 400. where P is the pressure in Pa and Q is the quantity in m3/s. The resistance of the mine is 0.19 Ns2/m8. The mine quantity in m3/s is
Two splits A and B are ventilated from an intake airway. Resistances of the splits are 0.5 Ns2m-8 and 0.8 Ns2m-8 respectively. A regulator is placed in split B to maintain a flow of 15 m3/s and 10 m3/s in splits A and B respectively as shown in the figure. The size of the regulator in m2 is
Determine the correctness or otherwise of the following Assertion [a] and the Reason [r]. Assertion: Both intake and return side stoppings must closed simultaneously in the event of sealing off a coal mine panel with explosion hazard following a fire. Reason: By continuously ventilating the area till simultaneously closure of the stoppings, the possibility of an explosion hazard due to gas built is avoided.
