What is the required flash point of the heat transfer fluid in a solar system relative to the design maximum non-operating temperature?

The correct answer pertains to the safety considerations for heat transfer fluids used in solar systems, which are essential for preventing ignition under various operational conditions. The required flash point of the heat transfer fluid must be at least 50 °F above the design maximum non-operating temperature to ensure a sufficient safety margin.

This requirement is designed to reduce the risk of fire or combustion that could occur if the heat transfer fluid were to reach temperatures near or at its flash point. By specifying a flash point that is significantly higher than the non-operating temperature, systems can mitigate the risks associated with heat build-up during idle periods, particularly in environments where ambient temperatures may fluctuate or reach levels that, without this precaution, could lead to unsafe conditions.

When selecting a heat transfer fluid, it is thus vital to consider both the operating temperatures and the flash point to comply with safety standards set by the International Mechanical Code, ensuring that the system maintains safe operational limits throughout its service life.