Mine Ventilation — Part 2 MCQs with Explanations

0.75% in the general body of the return air of any ventilation district and 1.25% in any place of the mine is the correct answer to “The percentage of inflammable gas in an u/g coal mine should not exceed”. This question is standard in competitive examination syllabi for Mine Ventilation.

4.56 is the correct answer to “A gas mixture contains CH 4 , C 2 H 6 and H 2 with respective concentration of 75%, 15% and 10% by volume. The lower explosibility limit of CH 4 , C 2 H 6 and H 2 are 5.0%, 3.3% and 4.2% respectively. The lower explosibility limit of the gas mixture, in percentage, is”. This question is standard in competitive examination syllabi for Mine Ventilation.

2.2 - 2.8 is the correct answer to “The voltage range of D6 methanometer . . . . . . . .”. This question is standard in competitive examination syllabi for Mine Ventilation.

Descensionally ventilated incline creates conditions for improved turbulent mixing of methane layer is the correct answer to “Ascensionally ventilated coal mine inclines ideally should have a higher methane layering number when compared to descensionally ventilated inclines. The reason is”. This question is standard in competitive examination syllabi for Mine Ventilation.

4.68% is the correct answer to “An air sample produces 8% CH 4 and 3% H 2 . If the lower flammability of CH 4 is 5% and H 2 is 4%, what is the lower flammability of the mixture”. This question is standard in competitive examination syllabi for Mine Ventilation.

Any open circuit rescue apparatus is the correct answer to “Which one of the following is used as an escape apparatus in u/g coal mine”. This question is standard in competitive examination syllabi for Mine Ventilation.

0.1635 is the correct answer to “The fan drift pressure readings and fan quantities are measured to be 500 Pa and 65 m 3 /s respectively at the time when NVP aids fan pressure. On reversal, the fan delivers a quantity of 50 m 3 /s while acting against NVP with fan drift pressure of 600 Pa. Assuming that the NVP remains constant in both cases the total resistance of the mine in Ns 2 /m 8 will be”. This question is standard in competitive examination syllabi for Mine Ventilation.

6.48 is the correct answer to “Samples of air collected in the intake and return gate roads of an advancing long wall face show 0.25% and 0.75% CH 4 , respectively. The panel has a production of 400t in an 8 hour shift when an air quantity of 18 m 3 /s passes through it. Then the methane emission in m 3 /te of coal mined is”. This question is standard in competitive examination syllabi for Mine Ventilation.

Foam extinguisher is the correct answer to “The type of fire extinguisher that must NOT be used in case of fire in an electric substation located in an underground metal mine is”. This question is standard in competitive examination syllabi for Mine Ventilation.

Kpa is the correct answer to “The S.I. unit of barometric pressure is”. This question is standard in competitive examination syllabi for Mine Ventilation.

$$\frac{{2\sqrt 2 }}{3}$$ is the correct answer to “For the same roadway roughness, area, length and velocity condition the ratio of resistances of a square roadway to that of a rectangular roadway having width and height ratio. 2 : 1 is”. This question is standard in competitive examination syllabi for Mine Ventilation.

3.10 is the correct answer to “The mean velocity of air current through an airway of 9m 2 cross-sectional area is found to be 1.5 m/s, If the mean methane content of air current is 0.6%, the layering index will be”. This question is standard in competitive examination syllabi for Mine Ventilation.

38.4 is the correct answer to “Air at dry bulb temperature of 27°C enters a 1200 m deep shaft. The specific heat of air-water vapour mixture is 1.03 KJ/kg °C. If the air goes through constant-moisture adiabatic auto compression, the air temperature at the bottom of the shaft in °C is”. This question is standard in competitive examination syllabi for Mine Ventilation.

9.79 is the correct answer to “The blade tip speed of a backward bladed centrifugal fan running at 300 rpm delivers 120 m 3 /s of air. If the tip speed of the blade is 47.12 m/s and width of the fan is 1.3 m then the radial velocity of air at the periphery of the impeller in m/s is”. This question is standard in competitive examination syllabi for Mine Ventilation.

1320 is the correct answer to “An underground coal mine panel produces 520 tonnes per day deploying 220, 200 and 192 persons in three shifts. As per CMR 1957, the minimum quantity of air in m 3 /min to be delivered at the last ventilation connection of the panel is”. This question is standard in competitive examination syllabi for Mine Ventilation.

$$4.015\sqrt {wg} $$ is the correct answer to “The formula for finding the velocity of air . . . . . . . .”. This question is standard in competitive examination syllabi for Mine Ventilation.

P-2, Q-1, R-4, S-3 is the correct answer to “Match the following: Mine gas Principal constituent P. Stink damp 1. CO Q. White damp 2. H 2 S R. Black damp 3. CH 4 S. Fire damp 4. CO 2”. This question is standard in competitive examination syllabi for Mine Ventilation.

5.4%, 14.8% is the correct answer to “The lower and upper limit of methane - air explosive mixture is”. This question is standard in competitive examination syllabi for Mine Ventilation.

1.52 is the correct answer to “The sp.gr of CO 2”. This question is standard in competitive examination syllabi for Mine Ventilation.

270.06 is the correct answer to “In a mine between upcast shaft and downcast shaft, two airways are connected in parallel and their resistances are 100 and 120 Ns -2 m -8 respectively. The resistance of upcast shaft, downcast shaft and the fan drifts are 10, 20, and 5 Ns -2 m -8 respectively. The rate of airflow through the split airway having resistance of 100 Ns -2 m -8 in m 3 /s is”. This question is standard in competitive examination syllabi for Mine Ventilation.

P-2, Q-1, R-3, S-4 is the correct answer to “Match the followings: Component of flame safety lamp Purpose of component P. Asbestos ring 1. Dissipation of heat of flue gas Q. Wire gauges 2. Formation of air-tight joints R. Outer glass 3. Arrest of explosion inside the lamp S. Combustion chimney 4. Separation of inlet air from flue gas”. This question is standard in competitive examination syllabi for Mine Ventilation.

61.55 is the correct answer to “Proximate analysis of 50 g of a coal sample shows the following: Moisture = 0.80 g Ash = 7.85 g Volatile matter = 15.90 g The fixed carbon in percentage on a dry, ash free basis is”. This question is standard in competitive examination syllabi for Mine Ventilation.

4.27 is the correct answer to “A pitot tube is inserted in a ventilation duct with the nose facing the air flow. A vertical U-tube manometer filled with alcohol (specific gravity 0.8) has been used for pressure measurements such that 10.2 mm is read as the total pressure and 8.8 mm as the static pressure. Given the density of air to be 1.2 kg/m 3 , the air velocity at the nose of the pitot tube in m/s is”. This question is standard in competitive examination syllabi for Mine Ventilation.

2 L/min is the correct answer to “Oxygen flow rate in the self contained breathing apparatus Proto Mark IV is”. This question is standard in competitive examination syllabi for Mine Ventilation.

336 is the correct answer to “A toxic gas flows into a mine working place at the rate of 2.52 m 3 /min. The concentration of the gas in the intake air is 0.25%. The minimum quantity of intake air in m 3 /min required to dilute the gas to its threshold limit value of 1.0% is”. This question is standard in competitive examination syllabi for Mine Ventilation.

6.13 is the correct answer to “A flammable mixture has 70% CH 4 and 30% CO. The lower flammability limits for these gases are 5% and 13% respectively. For the mixture, the lower flammability limit in % is”. This question is standard in competitive examination syllabi for Mine Ventilation.

P-3, Q-1, R-2, S-4 is the correct answer to “Given the following, Equation/formula/law Application P. Bernoulli equation 1. Pressure loss in laminar flow of fluid Q. Poiseuille equation 2. Drag loss due to regular obstructions in fluid flow R. Bromilow's formula 3. Energy conservation in ideal fluid flow S. Stokes law 4. Terminal settling velocity of fine particles in fluid the correct match is”. This question is standard in competitive examination syllabi for Mine Ventilation.

749.05 is the correct answer to “A mine ventilation system consists of two splits A and B with resistances of 0.8 Ns 2 m -8 and 3.2 Ns 2 m -8 , respectively as shown in figure. Trunk airways have resistance of 0.2 Ns 2 m -8 . The main mine fan is generating pressure of 500 Pa. The flows in the two splits are equalized by placing a booster fan in split B. Assume that the fan pressure does not change after installation of the booster fan. The size of the booster fan in Pa is”. This question is standard in competitive examination syllabi for Mine Ventilation.

50.8 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 . An identical fan is installed in the mine to operate in series with the existing fan. The new mine quantity in m 3 /s is”. This question is standard in competitive examination syllabi for Mine Ventilation.

2 is the correct answer to “For Indian coal mines, the 'maximum allowable concentration' of respirable dust containing 7.5% free silica in mg/m 3 is”. This question is standard in competitive examination syllabi for Mine Ventilation.

Active fire is the correct answer to “In an underground coal mine area the graham's ratio found 3% is the indication of”. This question is standard in competitive examination syllabi for Mine Ventilation.

540 ∗ 10-3 is the correct answer to “A man exhales 0.002 m 3 of CO 2 per min when working in a confined space in underground. Assuming that the fresh air contains 0.03% CO 2 , the minimum quantity of fresh air to be supplied per person in m 3 /min, so that concentration of CO 2 , in air never crosses 0.4%, will be”. This question is standard in competitive examination syllabi for Mine Ventilation.

Wet bulb is the correct answer to “The thermometer bulb covered with moist cloth called as”. This question is standard in competitive examination syllabi for Mine Ventilation.

Class C fire is the correct answer to “CO 2 is best suited for extinguisher”. This question is standard in competitive examination syllabi for Mine Ventilation.

Coolant canister is the correct answer to “A gas mask does not include”. This question is standard in competitive examination syllabi for Mine Ventilation.

51.83 is the correct answer to “In a longwall panel, the main gate road is 1000 m long, 4.5 m wide and 2 m high. The gate road is to be used for airflow at the rate of 17 m 3 /s. Considering a coefficient of resistance of airways of 0.01, the pressure in Pa required to maintain the airflow in the gate road is”. This question is standard in competitive examination syllabi for Mine Ventilation.

Sweating of strata is the correct answer to “The early indication of spontaneous heating of coal can be given by”. This question is standard in competitive examination syllabi for Mine Ventilation.

1250 m3/min is the correct answer to “Quantity of air to be circulated to u/g workings where 150 worker employed in a largest shift and daily production 500 te will be”. This question is standard in competitive examination syllabi for Mine Ventilation.

Self contained breathing apparatus is the correct answer to “The chemical protosorb used in”. This question is standard in competitive examination syllabi for Mine Ventilation.

$$\frac{{101325}}{{760}} \times h\,N/{m^2}$$ is the correct answer to “If the barometric pressure at a place is 'h' mm of mercury, convert into SI units.”. This question is standard in competitive examination syllabi for Mine Ventilation.