A psychrometric chart is a graph that illustrates the physical and thermal properties of humid air. You must understand how a psychrometric chart works to visualize the concept of how heated air contains more moisture than cold air, and when the air cools condensation occurs. The psychrometric chart comprises a dry-bulb temperature scale on the horizontal axis moisture ratio scale on the vertical axis. It represents a curved boundary saturated air or 100 percent moisture retention capacity. To detect air temperature and humidity problems, you also need to understand how the psychrometric chart works.
Things that you need
- Psychrometric chart
- Hygrometer (optional)
- Examine the graph components of the psychrometric chart piece by piece. Look at the axes in the graph. Find the dry bulb temperature scale on the horizontal axis or X-axis. Find the moisture ratio scale (or moisture content) on the vertical axis or Y-axis. Look for the curved line that represents the 100% moisture saturation or the moisture business capacity. The graph also shows other crucial humid air properties such as wet – bulb temperature, enthalpy (tangible and latent energy), dew point or saturation temperature, relative humidity, and specific volume.
- Use a sling psychrometer to obtain a dry – bulb and wet bulb temperature from your sample. Find the intersection of the bare bulb and the wet-bulb temperature on the psychrometric map. First, look at the dry-bulb temperature along the x-axis and find the line for the dry-bulb temperature that runs vertically through the graph. The wet-bulb temperature is the dotted line that leads to the curved boundary saturation line.
- Read the intersection read for the vertical dry-bulb temperature line and the diagonal wet bulb temperature line. This is known as the state point for the air temperature measured. The state point for the air temperature allows you to tell the contents of water vapor and the enthalpy in the air.
- Determine the relative humidity through the labeled corresponding humidity line. The line must curve from left to right along with the graph. Also, find the dew point temperature on the indicated line on the chart. This rule should also rotate from left to power through the figure to the saturation boundary line.
- Evaluate the air properties obtained from the psychometric map and take the necessary measures to find the required environmental solutions.