Mine Ventilation & Atmospheric Monitoring Flashcards

What is the MSHA permissible exposure limit (PEL) for carbon monoxide in underground mine atmospheres?

Answer: 50 ppm

MSHA sets a PEL of 50 ppm for carbon monoxide as an 8-hour time-weighted average in underground mines, consistent with established occupational health standards.

In the Coward's Flammability Triangle, which three gases are used to describe explosive atmospheres?

Answer: Methane (or fuel gas), oxygen, and nitrogen

Coward's Triangle plots fuel gas (e.g., methane), oxygen, and nitrogen concentrations to identify the explosive zone, helping mine safety professionals determine whether a mine atmosphere is within the explosive range.

What does a water-gauge manometer measure in a mine ventilation survey?

Answer: The pressure differential (ventilation pressure) between two points in the mine

A manometer measures the pressure difference between two locations in the mine, allowing engineers to calculate resistance and fan performance in the ventilation circuit.

Auxiliary ventilation in underground mining is used to:

Answer: Ventilate dead-end headings and development faces where main airflow cannot reach

Auxiliary ventilation systems (using line brattice or duct-and-fan setups) extend ventilation into blind headings and development entries that are not on the main airflow circuit.

Which type of ventilation system is characterized by two separate airway systems where intake and return air travel in opposite directions through parallel entries?

Answer: Antitropal ventilation

Antitropal (or counterflow) ventilation has intake and return airways traveling in opposite directions and is considered safer for coal mines because it separates fresh and contaminated air in parallel entries.

In a flame safety lamp, what indicates the presence of flammable gas (methane) in the mine atmosphere?

Answer: The flame elongates and develops a blue cap above it

When methane is present, it ignites and creates a characteristic blue halo or elongated blue cap above the main flame, with the height of the cap indicating the approximate concentration.

What is the purpose of conducting a ventilation survey in an underground mine?

Answer: To measure airflow quantities and pressures to evaluate ventilation system efficiency and plan improvements

A ventilation survey measures air quantities, velocities, and pressures throughout the mine to assess whether the ventilation system meets regulatory requirements and to identify where improvements are needed.