What is the main function of an expansion tank in a steam system?

The main function of an expansion tank in a steam system is to accommodate changes in water volume during heating and cooling. As water is heated to generate steam, it expands significantly. Conversely, when the steam cools and condenses back into water, the volume decreases. An expansion tank provides a space for this varying volume of water, allowing the system to operate smoothly and preventing excessive pressure buildup that could potentially damage components or lead to system failures. This mechanism helps maintain system pressure within safe limits and ensures efficient operation of the steam system.

In contrast, cooling steam before it enters the system is not the role of the expansion tank; this process typically involves separate equipment designed for temperature regulation. Additionally, while an expansion tank can help manage pressure indirectly by accommodating volume changes, its primary purpose is not to hold excess pressure. Instead, maintaining system pressure is usually handled by pressure relief valves or other controls. Finally, filtering impurities from the water supply is managed through different water treatment systems and not through the expansion tank, whose purpose focuses solely on volume fluctuation management.