Once a boiler purge is complete, within what time frame must fires be lighted?

The correct choice specifies that fires must be lighted within 5 minutes after a boiler purge is complete. This time frame is critical because it helps ensure safe operation and prevents any potential hazards that may arise from residual gases or unburned fuel that can linger in the system after purging. The boiler purge process is designed to clear out flammable vapors and other combustion byproducts, and waiting too long before igniting the burner could lead to dangerous situations such as gas accumulation. By initiating the lighting of the fires within this 5-minute window, operators can maintain a secure environment and ensure that the boiler is prepared for safe and effective operation.

While other time frames like 3, 7, or 10 minutes might seem plausible, they do not align with the established safety protocols and guidelines that govern boiler operations. Understanding this timing is essential for maintaining not only operational efficiency but also safety standards in boiler management.