How many safety valves are required on a boiler with more than 500 square feet of heating surface?

For a boiler with more than 500 square feet of heating surface, the requirement is for two or more safety valves. This stipulation is grounded in the need to ensure maximal safety in case one of the valves fails or requires maintenance. Safety valves are critical components that release excess pressure from the boiler system, preventing potential explosions or catastrophic failures.

By having two or more safety valves, it guarantees that the boiler can continue to operate safely even if one valve is out of commission. This redundancy is essential in larger systems where the potential for generated pressure is significant, aligning with safety standards and best practices in engineering.

Smaller boilers or those with less heating surface may only require a single safety valve, reflecting the lower risk associated with their operation. Thus, the requirement for multiple safety valves is directly related to the increased risks involved with larger boilers, underscoring the need for enhanced safety measures.