What happens to pressure when steam condenses in a closed vessel?

When steam condenses in a closed vessel, the pressure decreases. This occurs because steam is essentially water vapor, which occupies a larger volume in its gaseous state compared to its liquid state. As the steam condenses into water, it transitions from a vapor to a liquid, thus occupying less space.

The reduction in volume is what leads to a drop in pressure within the closed vessel. In a closed system, this principle aligns with the ideal gas law, which states that at constant temperature, a decrease in volume results in a decrease in pressure. Therefore, as steam condenses, the overall pressure within the vessel declines as fewer gas molecules are present to exert force on the walls of the container. Understanding this fundamental principle is critical in operations involving steam systems, as managing pressure is essential for safety and efficiency in commercial food equipment.