Which of the following describes how an auxiliary fan must be located and operated, and how the minimum panel air flow is determined?

• A. An auxiliary fan is located and operated to prevent air recirculation, and the panel air flow equals the sum of open circuit capacities of all operating auxiliary fans in operation plus 30% of the largest.
• B. An auxiliary fan must be placed only in intake areas and has no minimum air flow requirement.
• C. Auxiliary fans must be automatically shut off if ventilation system fails totally.
• D. Auxiliary fans are not required to be monitored.

Answer: (D)

The idea being tested is how auxiliary fans relate to the overall panel air flow and how monitoring is applied. In this exam context, the statement that auxiliary fans are not required to be monitored is the point of emphasis: the question is targeting whether there is a separate monitoring requirement for each auxiliary unit versus relying on the broader ventilation monitoring system. If the system as a whole is being monitored for panel air flow and face conditions, the auxiliary fans themselves don’t carry an additional mandatory monitoring requirement in this framing.

Think about what determines minimum panel air flow: it comes from the mine’s ventilation plan and the need to maintain adequate dilution and air quality at the faces, rather than a fixed arithmetic rule based on the capacities of auxiliary fans. The other options propose specific formulas or location rules or automatic shutdowns that aren’t universally mandated, so they don’t align with the idea being tested here.

So, the choice that aligns with the stated monitoring focus is that auxiliary fans are not required to be monitored.