As the amount of water in a mixture decreases, which quantity increases?

• A. Temperature
• B. Pressure
• C. Steam Quality
• D. Moisture Content

Answer: (C)

Steam quality is the portion of a saturated mixture that is vapor. It is defined as the mass of vapor divided by the total mass of the mixture. When the amount of water in the mixture decreases, the liquid portion shrinks while the vapor portion stays the same or grows, so the vapor fraction relative to the total increases. That means the steam quality rises. In a saturated system, temperature and pressure are set by the saturation state and don’t necessarily increase just because there is less liquid. Moisture content directly tracks how much water is present and would decrease as the liquid portion diminishes. So, the quantity that increases as water content decreases is steam quality.