A hood exhaust must be provided in a room when what condition is met?

The requirement for a hood exhaust in a room is primarily linked to safety considerations related to high surface temperatures and the presence of refrigerants. When surface temperatures exceed 800°F and a single circuit contains more than 6.6 lbs of refrigerant, it indicates a potential risk for overheating and refrigerant release, which can lead to hazardous conditions.

The rationale for needing a hood exhaust under these specific circumstances is to ensure that any heat generated in the system is effectively ventilated, reducing the risk of fire or explosion. High refrigerant loads combined with elevated temperatures necessitate proper ventilation to safeguard both personnel and the environment.

The specific parameters outlined in choice B provide a clear guideline for when exhaust systems are essential, aligning with safety standards that help prevent malfunction or accidents in HVAC operations. Therefore, this option best encapsulates the criteria for requiring a hood exhaust in a room.