Psychrometric Chart PDF

Psychrometric Chart in PDF download free from the direct link below.

Psychrometric Chart - Summary

The psychrometric chart is an essential industry-standard tool that helps in understanding the relationships between dry air, moisture, and energy. If you work on designing or maintaining air-conditioning systems in buildings, knowing how to read this chart can significantly simplify your tasks. With the psychrometric chart, engineers and technicians can evaluate psychrometric processes better and find effective solutions. This chart is fundamental in comprehending the interactions between different air supply parameters and relative humidity.

Parts of a Psychrometric Chart

A psychrometric chart is made up of eight standard components:

  • Temperatures
  • Dry Bulb – This is the temperature reading you see on a regular thermometer. A psychrometric chart usually shows these temperature ranges:
    • Low temperatures from -20 degrees FDB to 50 degrees FDB
    • Normal temperatures from 20 degrees FDB to 100 degrees FDB
    • High temperatures from 60 degrees FDB to 250 degrees FDB
    • Wet Bulb – This is the temperature recorded when a standard thermometer’s sensing bulb is covered with a wet wick and exposed to airflow.
    • Dew Point – At this temperature, moisture begins to condense from the air.
  • Latent Heat Flow – 60(latent heat of vaporization of water in Btu/lb (970 at sea level))(density of air in lb/ft³)(air flow in ft³/min)(humidity ratio difference in lb water/lb dry air)
  • Moisture Content – Also called humidity ratio, this indicates the total weight of water vapor contained in one pound of dry air.
  • Relative Humidity – This term means the percentage of water vapor per pound of dry air compared to how much water vapor the air can hold at its current temperature.
  • Vapor Pressure – Measured in inches of mercury, vapor pressure shows the pressure that water vapor exerts in the air.
  • Standard Air Dot – This dot represents standard air, typically at 70 degrees Fahrenheit with 54% relative humidity and 60 gr/lb of specific humidity.
  • Specific Volume & Density – Specific volume is noted in cubic feet per pound, indicating how much space air takes up per pound.
  • Enthalpy – This represents heat energy, measured in Btu (British thermal unit) per pound of dry air.
  • Sensible Heat Ratio – This ratio is calculated by dividing the total sensible heat flow by the total heat flow.
  • Sensible Heat Flow – 60(specific heat of air in Btu/lb ºF (0.24 at 72ºF))(density of air in lb/ft³)(air flow in ft³/min)(| supply air temperature – conditioned room temperature |)

How to Read the Psychrometric Chart

Reading a psychrometric chart can be done easily by following these steps:

Step 1: Locate the dry bulb temperature, which is displayed along the bottom axis in degrees Fahrenheit or Celsius, and identify the corresponding vertical line for each temperature.

Step 2: Find the humidity ratio, marked as a mixing ratio on the right vertical axis. Humidity ratio can be expressed in grains of moisture per pound of dry air or grams of moisture per kilogram of dry air.

Step 3: Point out the left-most curved line, which indicates the saturation curve at 100% relative humidity.

Step 4: Identify the inner curved lines that represent various levels of relative humidity percentages.

Step 5: Locate the dew point, marked by a vertical line on the right side of the chart, which extends horizontally across the chart.

Step 6: On the opposite side of the dew point’s vertical line, you’ll find the vapor pressure scale, also shown as horizontal lines across the chart.

Step 7: Check the outer sides of the chart for scales that represent enthalpy. Use a ruler to align these scales across the chart.

Step 8: Find the second set of diagonal lines which show wet bulb temperatures. Though they are close to the enthalpy lines, they are not perfectly parallel.

You can easily download the Psychrometric Chart PDF using the link provided below for your reference and further reading. Enjoy using the psychrometric chart in your air-conditioning tasks! 📊

Psychrometric Chart PDF Download