Mine Ventilation - Study Mode

[#111] The liquid employed in aneroid barometer.
Correct Answer

(D) None

Explanation

Solution: 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.

[#112] The mechanical mixture of gases existing in a mine given off after explosion called
Correct Answer

(D) After damp

[#113] A Drager Gas Mask does not filter
Correct Answer

(B) Nitrous fumes

[#114] The resistances of two splits A and Bare 0.35 Ns 2 m -8 and 0.05 Ns 2 m -8 respectively. The combined resistance of the shafts and trunk airways is 0.4 Ns 2 m -8 . A booster fan is planned to be installed in split A to increase the quantity flowing through it. Assuming that the surface fan continues to operate at a constant pressure of 1000 Pa, the critical pressure of the booster fan in Pa is
Correct Answer

(B) 875

Explanation

Solution: 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

[#115] 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
Correct Answer

(A) 502.31