Mine Ventilation — Part 1 MCQs with Explanations

An aneroid barometer is a type of barometer that doesn't use liquid to measure atmospheric pressure. It uses a small, flexible metal box called an aneroid cell . This box is partially evacuated (air removed) , so changes in atmospheric pressure cause it to expand or contract. These movements are mechanically amplified and displayed on a dial to indicate the pressure. Since it relies on a mechanical system and not a liquid column, the answer is "None" . Options A (Mercury), B (Water), and C (Petrol) are all liquids but are not used in aneroid barometers . Mercury is used in mercury barometers, which is a different type of barometer.

To find the critical pressure of the booster fan, we can use the equation: Combined Resistance = Surface Fan Pressure + (Booster Fan Pressure / Flow Quantity) Given: Resistance of Split A = 0.35 Ns 2 m -8 Resistance of Split B = 0.05 Ns 2 m -8 Combined Resistance = 0.4 Ns 2 m -8 Surface Fan Pressure = 1000 Pa (constant) Flow Quantity through Split A (without booster fan) = Resistance of Split A / Surface Fan Pressure Flow Quantity through Split A = 0.35 Ns 2 m -8 / 1000 Pa = 0.00035 m 3 /s Flow Quantity through Split B = Resistance of Split B / Surface Fan Pressure Flow Quantity through Split B = 0.05 Ns 2 m -8 / 1000 Pa = 0.00005 m 3 /s Now, using the combined resistance equation, we can calculate the critical pressure of the booster fan (let's denote it as Pb): Combined Resistance = Surface Fan Pressure + (Pb / Flow Quantity through Split A) 0.4 Ns 2 m -8 = 1000 Pa + (Pb / 0.00035 m 3 /s) Now, solve for Pb: Pb = 0.4 Ns 2 m -8 - 1000 Pa * (1 / 0.00035 m 3 /s) Pb = 0.4 Ns 2 m -8 - 2857.14 Pa Pb = 875 Pa Therefore, the critical pressure of the booster fan is 875 Pa

After damp is the correct answer to “The mechanical mixture of gases existing in a mine given off after explosion called”. This question is standard in competitive examination syllabi for Mine Ventilation.

Nitrous fumes is the correct answer to “A Drager Gas Mask does not filter”. This question is standard in competitive examination syllabi for Mine Ventilation.

502.31 is the correct answer to “A mine airway having cross-section of 2.2 m × 2.2 m and length 500 m contains a bend. Given that the airway friction factor is 0.01 Ns 2 m -4 , shock loss factor for the bend is 0.07 and density of air is 1.2 kg/m 3 , the equivalent length of the airway in m is”. This question is standard in competitive examination syllabi for Mine Ventilation.

Ring rose fire damp detector is the correct answer to “Methane detector works on the principle of diffusion combustion contraction is”. This question is standard in competitive examination syllabi for Mine Ventilation.

14.4 mm is the correct answer to “A mine fan delivers 50 m 3 /s of air at a fan drift of 10 mm of w.g. It is proposed to increase the quantity to 60 m 3 /s of air. the required w.g. shall be”. This question is standard in competitive examination syllabi for Mine Ventilation.

0.44 is the correct answer to “When two identical and parallel intake roadways are changed to three identical and parallel intake roadways of same size and length, the ratio of new equivalent resistance to old equivalent resistance will be”. This question is standard in competitive examination syllabi for Mine Ventilation.

19% is the correct answer to “The oxygen concentration in u/g working should not be less than”. This question is standard in competitive examination syllabi for Mine Ventilation.

H2S is the correct answer to “Which can be found by blotting paper soaked in lead acetate changes its colour black.”. This question is standard in competitive examination syllabi for Mine Ventilation.

0.99 is the correct answer to “In a coal mine district, air flows at a rate of 30 m 3 /s at a pressure of 1200 Pa. The density of air is 1.2 kg/m 3 . The mine management decided to reduce the flow rate of air to 20 m 3 /s using a regulator without changing the ventilation pressure. The area of regulator expressed in m 2 will be”. This question is standard in competitive examination syllabi for Mine Ventilation.

Nitras fumes is the correct answer to “After blasting which gas come out.”. This question is standard in competitive examination syllabi for Mine Ventilation.

1.0 is the correct answer to “A Roadheader district produces 20 mg/m 3 of airborne dust with the following size distribution: Size up to Cumulative wt% 1 μm 1 5 μm 5 10 μm 10 20μm 20 50μm 50 >50μm 100 The concentration of respirable fraction of dust in mg/m 3 is”. This question is standard in competitive examination syllabi for Mine Ventilation.

More than 1 m/s is the correct answer to “The wet bulb temperature of air at a particular place in a mine is 31°C, then the velocity of air in that place should be”. This question is standard in competitive examination syllabi for Mine Ventilation.

4.70 is the correct answer to “Intake air containing 0.2% methane enters a section of an underground mine where emission of methane is 0.05m 3 /s. Assuming that the threshold limit value of methane is 1.25%, the minimum quantity of fresh air required in m 3 /s is”. This question is standard in competitive examination syllabi for Mine Ventilation.

Area ABF + Area CDEF is the correct answer to “The figure shows PV (pressure-volume) diagram of a mine ventilated by both natural means and an exhaust fan. The total ventilation energy is represented by”. This question is standard in competitive examination syllabi for Mine Ventilation.

Near is the correct answer to “The black damp accumulates . . . . . . . . to the floor”. This question is standard in competitive examination syllabi for Mine Ventilation.

0.75; 1.25 is the correct answer to “The inflammable gas should be below . . . . . . . . % in the general body of the retunr air way of any ventilating district and below . . . . . . . . % at any place in the mine.”. This question is standard in competitive examination syllabi for Mine Ventilation.

28 is the correct answer to “A centrifugal fan rotating at 500 rpm. delivers 70 m 3 /s of air. If the speed is reduced to 200 rpm. the quantity of air delivered in m 3 /s will be”. This question is standard in competitive examination syllabi for Mine Ventilation.

332 is the correct answer to “A fan running at a speed of 280 rpm circulates 105 m 3 /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%. If the fan pressure is to be increased by 200 Pa by changing the fan speed. the fan speed in rpm will become”. This question is standard in competitive examination syllabi for Mine Ventilation.

30 is the correct answer to “In a mine ventilation system, the resistances of two splits A and B are 0.5 Ns 2 m -8 and 2 Ns 2 m -8 respectively. Combined resistance of two shafts and trunk airways is 0.7 Ns 2 m -8 . A quantity of 20 m 3 /s of air passes through split A. The total air quantity passing the mine in m 3 /s is”. This question is standard in competitive examination syllabi for Mine Ventilation.

NiCal is the correct answer to “Model OXD-2M O 2 defficiency meter contains rechargable battery of . . . . . . . .”. This question is standard in competitive examination syllabi for Mine Ventilation.

0.74 is the correct answer to “A fan circulates 24 m 3 /s of air at a pressure of 1200 Pa in a ventilation district. It is intended to reduce the air quantity to 16 m 3 /s by placing a regulator. Assuming the pressure remains unchanged, the size of the regulator in m 2 is”. This question is standard in competitive examination syllabi for Mine Ventilation.

540 and 45.0 is the correct answer to “A mine fan produces 30 m 3 /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 m 3 /s generated by the fan will be”. This question is standard in competitive examination syllabi for Mine Ventilation.

186.7 is the correct answer to “Air flows at 2 m 3 /s through a forcing fan duct of 0.3 m 2 having uniform cross-section. The duct resistance is 40 Ns 2 m -8 and air density is 1.2 kg/m 3 . The total pressure generated by the fan in Pa is”. This question is standard in competitive examination syllabi for Mine Ventilation.

102, 177 and 228 is the correct answer to “While measuring average air velocity of air flowing through a circular duct using precise traversing with equal area method, the radii r 1 , r 2 and r 3 , in mm, as shown in the figure of the three circles should be”. This question is standard in competitive examination syllabi for Mine Ventilation.

0.5 R is the correct answer to “The resistances of each branches KL, LM, MN, NK is R and that of LN is 1.414 R. the equivalent resistance between K and M is”. This question is standard in competitive examination syllabi for Mine Ventilation.

923 - 1023°C is the correct answer to “Ignition temperature of methane is”. This question is standard in competitive examination syllabi for Mine Ventilation.

57.6 is the correct answer to “An exhaust fan attached to an evasee of 18 m 2 cross-sectional area at the outlet circulates 150 m 3 /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/m 3 . The quantity of air circulated in the mine in absence of evasee is 120 m 3 /s. The eva see efficiency in % is”. This question is standard in competitive examination syllabi for Mine Ventilation.

Surroundings can be hot and humid during rescue is the correct answer to “A coolant is desirable component in the design of a self- contained breathing apparatus since”. This question is standard in competitive examination syllabi for Mine Ventilation.

12% is the correct answer to “The methane air mixture become explosive with the minimum percentage of oxygen.”. This question is standard in competitive examination syllabi for Mine Ventilation.

500 is the correct answer to “A fan running at a speed of 280 rpm circulates 105 m 3 /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”. This question is standard in competitive examination syllabi for Mine Ventilation.

40 is the correct answer to “Pressure characteristic of a mine fan is given by. P = -0.06Q 2 + 400. where P is the pressure in Pa and Q is the quantity in m 3 /s. The resistance of the mine is 0.19 Ns 2 /m 8 . The mine quantity in m 3 /s is”. This question is standard in competitive examination syllabi for Mine Ventilation.

2.1 is the correct answer to “Two splits A and B are ventilated from an intake airway. Resistances of the splits are 0.5 Ns 2 m -8 and 0.8 Ns 2 m -8 respectively. A regulator is placed in split B to maintain a flow of 15 m 3 /s and 10 m 3 /s in splits A and B respectively as shown in the figure. The size of the regulator in m 2 is”. This question is standard in competitive examination syllabi for Mine Ventilation.

Both A and C is the correct answer to “Quantity of air to be circulated to u/g workings depends on”. This question is standard in competitive examination syllabi for Mine Ventilation.

Both [a] and [r] are true and [r] is no the correct reason for [a] is the correct answer to “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.”. This question is standard in competitive examination syllabi for Mine Ventilation.

50 atoms is the correct answer to “Critical pressure of oxygen.”. This question is standard in competitive examination syllabi for Mine Ventilation.

Reynolds number and asperity ratio is the correct answer to “Moody diagram represents resistance coefficient in terms of”. This question is standard in competitive examination syllabi for Mine Ventilation.

P-3, Q-2, R-4, S-1 is the correct answer to “Given the following. Rescue apparatus Characteristic P. Draeger BG-4 1. Open circuit chemical oxygen self-rescuer Q. MSA IW-65 2. Filter type self-rescuer R. Draeger Pulmotor 3. Self-contained breathing apparatus S. Oxvoks 4. Resuscitation apparatus The correct match is”. This question is standard in competitive examination syllabi for Mine Ventilation.

Kata thermometer is the correct answer to “Which of the following instrument is used to measure the cooling power of the air”. This question is standard in competitive examination syllabi for Mine Ventilation.