It is calculated by dividing the total mass of water vapor by the volume of the air. Use the horizontal lines extending from this axis to trace the humidity ratio throughout the chart. The vertical, or “Y” axis of the chart marks the amount of moisture per pound or kilogram. How do you find the humidity ratio on a psychrometric chart?įind the humidity ratio labeled on the right vertical axis. The intersection of the vertical 78☏ dry-bulb line and the diagonal 65☏ wet-bulb line has now established a state point for the measured air. Wet-bulb temperature is located along diagonal dotted lines leading to scale readings at the upper, curved boundary marked saturation temperature. How do you find the wet bulb temperature from a psychrometric chart? The dew point is measured vertically and usually measured in degrees Fahrenheit or degrees Celsius, on this chart it is measured in Fahrenheit. The dew point is represented on the chart by Point 3. For this specific graph, it is measured in inches of mercury.
Vapor pressure is measured in units of mercury.
