A convenient, precise and customizable psychrometric chart & calculator tool for 25 26 27 28 29 30 m^3/kg(d.a) 10% 20% 30% 40% 50% 60% 70%. Psychrometrics, psychrometry, and hygrometry are names for the field of engineering . The ASHRAE-style psychrometric chart, shown here, was pioneered by. Use chart to analyze processes involving moist Psychrometric chart: Example 1 . Given: T = 25°C . m wide x m long, and the boards are separated by.

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The various lines shown psgchrometric the chart are as follows please refer the figs below: Identify 2 known measurements that are on the chart. By continuing to use our site, you agree to our cookie policy. Next to or along the same vertical line as the dew point measurements, there will be markings denoting the various vapor pressures in inches of mercury or millibars.

How to Read a Psychrometric Chart: 11 Steps (with Pictures)

From any two independent ones of the six parameters dry bulb temperature, wet bulb temperature, relative humidity, humidity ratio, specific enthalpy, and specific volume, all the others can be determined. Notice that on the saturation curve the wet and dry bulb temperatures have the same values.

These lines are drawn straight, not always parallel to each other, and slightly inclined from the vertical position. Psyxhrometric from the original on For this reason a Psychrometric Chart relating all the relevant variables was developed which is extremely useful for designing and evaluating air-conditioning and cooling tower systems. The ratio of the vapor pressure of moisture in the sample to the saturation pressure at the dry bulb temperature of the sample.

A simplified definition is the temperature at which the water vapour turns into “dew” Chamunoda Zambuko psychrometrkc Pick any 2 known measurements available and plot them on the chart where the lines intersect. The vertical lines shown in the chwrt are the constant DB temperature lines and all the points located along a particular vertical line have same DB temperature.


Around the extremes of the chart and just outside of the saturation curve, locate the diagonal scales which represent enthalpy in BTU per pound of dry air. Other websites that we found interesting is that of Wikipedia on Psychrometrics.

The DB temperature increases from the left to the right. Changes in statesuch as when two air streams mix, can be modeled easily and somewhat graphically using the correct psychrometric chart for the location’s air pressure or elevation relative to sea level. The major simplifying assumption in the construction of the chart is that the enthalpy of the mixture is assumed to be constant throughout the adiabatic saturation process described in Section a.

Various Lines and Curves in the Psychrometric Chart All the properties of air indicated in the psychrometric chart are calculated at the standard atmospheric pressure. Definitely review both guides before continuing.

What is Psychrometric Chart? Introduction to Reading the Psychrometric Properties of Air

The inner scale represents sensible-total heat ratio SHF. A psychrometer is a device that includes both a dry-bulb and a wet-bulb thermometer. Refer to the link: In many industrial applications it is important to avoid condensation that would ruin product or cause corrosion. The psychrometric chart looks complicated with vast numbers of lines and curves in it, psychrometrric is very easy to understand if you know the basic properties of air.

Both guides reduce the confusion by separately explaining 4 of the 6 sets of curves which make up a psychrometric chart. As the chrt humidity increases at a certain temperature, the specific volume of the air also increases. Already answered Not a question Bad question Other. Analogous to the specific volume of a psycchrometric substance.

These lines are oblique lines that differ slightly from the enthalpy chzrt. This defines the “comfort zone” which is portrayed on the Psychrometric Chart as shown below. The scale of the DP and WB temperature is the same, however, while the constant WB temperature lines are diagonal lines extending downwards, the constant DP temperature lines are horizontal lines.


Although the principles of psychrometry apply to any physical system consisting of gas-vapor mixtures, the most common system of interest is the mixture of water vapor and air, because of its application in heating, ventilating, and air-conditioning and meteorology.

Identify the diagonal specific volume lines throughout the chart. The saturation temperature of the moisture present in the sample of psychrometriv, it can also be defined as the temperature at which the vapour changes into liquid condensation.

Use the horizontal lines extending from this axis to trace the humidity ratio throughout the chart. Chapter 2, Measurement of Temperature.


This type of cooler is extremely popular in hot, dry climates, and is popularly known as a Swamp Cooler. Thanks for letting us know. Technically, the temperature registered by the dry-bulb thermometer of a psychrometer.

The Mollier diagram coordinates are enthalpy and humidity ratio. Together, they cited information from 12 referenceswhich can psychrometrric found at the bottom of the page. An interesting and informative description on Psychrometric Chart Use for livestock and greenhouse applications has been presented in a University of Connecticut website by Michael Darre. In meteorology and psychrometrics the word temperature by itself without a prefix usually means dry-bulb temperature.

Try to be as exact as possible when using the chart to read other measurements, and mark your answers in the proper units for that measurement.

These intersect the saturation curve at DBT point. Molds and fungi can be controlled by keeping relative humidity low. The various lines shown in the chart are as follows please refer the figs below:.