To read a psychometric chart, find the dry bulb temperature on the horizontal or X axis. Check the vertical or Y axis for the humidity ratio. The uppermost curved line on the chart shows the saturation curve when the relative humidity is 100 percent.
How do you read a psychrometric chart example?
Take a ruler and draw a vertical line at the dry bulb temperature of 70 and draw a horizontal line where the dew point is 50. The point where these two lines intersect is known as a ‘state point’. Plot the state point and you can also read the rel- ative humidity, wet bulb, enthalpy, vapor pressure and humidity ratio.
What are the 2 measurements read by a psychrometer?
A psychrometer measures humidity by taking both a wet-bulb and a dry-bulb temperature reading. With those two values known, the other properties of the air, including its moisture content, can be determined by computation or by reading a psychrometric chart.
How do you calculate humidity ratio?
Humidity Ratio (W)
Humidity ratio is measured in units of pound-mass of water per pound-mass of dry air. By multiplying by 7000 [grains per pound-mass], this value may be expressed in grains of water per pound-mass of dry air.
How do you read absolute humidity on a psychrometric chart?
On the vertical line corresponding to the temperature of 20°C, we go up until we reach the 60% HR curve. Moving to the right until the end of the diagram we find the absolute humidity vertical line. This give us the information that our air contains 8.77 g of water vapor.
What should relative humidity be in a house?
Every homeowner should own a hygrometer that measures temperature and relative humidity (RH). The ideal relative humidity for health and comfort is about 40–50%. In the winter months, it may have to be lower than 40% RH to avoid condensation on the windows.
What is the best indoor humidity level?
The ideal relative humidity for health and comfort is somewhere between 30-50% humidity, according to the Mayo Clinic. This means that the air holds between 30-50% of the maximum amount of moisture it can contain.
What can happen to a house if relative humidity is real high?
High humidity can cause problems in your home if relative humidity regularly exceeds 60%. When the air contains water vapor above that level, mold and mildew start to grow, while excess moisture can cause rot, damaging your belongings.
How do you use a swing thermometer?
Once the wick is wet, hold the handle and whirl the psychrometer in the air. Whirling generates airflow around both the wet and dry bulbs. This action allows water in the saturated wick to evaporate, thereby reducing the temperature of the wet-bulb thermometer. The dry bulb temperature will remain unchanged.
Why are human hairs often used in a hair hygrometer?
Strands of hair can relax and lengthen when the humidity increases, and then contract again when the humidity decreases. In fact, the rate of change in the length of hair strands is so dependable that they can actually be used as the basis for a hygrometer, a device that measures the humidity level in the air.
What is difference between humidity ratio and relative humidity?
Difference Between Relative Humidity and Humidity Ratio
The Humidity Ratio is how much ‘air’ is in the air versus the amount of water. Relative Humidity on the other hand, takes the humidity ratio, and includes the air temperature, and the maximum amount of water the air can hold, and displays it as a percentage.
What is the symbol for humidity?
2 Humidity. Absolute humidity is the quality of water vapor in the wet air of unit volume (1 m3), for which the symbol is ρv. Because water vapor in humid air has the same volume as that of wet air, the absolute humidity is the density of water vapor in the wet air.
