Calculate humidity parameters such as relative humidity, dew point, frost point, vapor concentration, specific humidity, mixing ratio, and more parameters. - recommended humidity calculator for rotronic products.
The PST Rotronic Relative Humidity Calculator is based on the Hyland and Wexler (1983) formula for measuring water vapor pressure over a range of temperatures.
It accurately represents the saturation vapor pressure of water over liquid and solid phases.
The Hyland and Wexler (1983) equation:
ln (Pvap) = A + B / (T + C)
Pvap is the water vapor pressure in Pascal (Pa).
T is the temperature in degrees celsius (°C).
A, B, and C are constants that vary depending on the water phase (liquid or solid).
The Humidity Calculator is built to focus on Relative Humidity measurement for engineers. Users can also choose between different units and parameter inputs such as dew point, wet-blub temperature, frost point, vapor concentration, and more. It can be used as a standalone tool or in combination with Rotronic humidity products.
Using the PST Rotronic Relative Humidity Calculator is easy. 1) Choose the parameter you want to measure. 2) Enter the temperature and pressure. 3) Select the units in which you want to view your result.
Watch the quick video below demonstrating how to use the PST Rotronic Relative Humidity Calculator.
Relative humidity is the measurement of how close the air (or other gas) is to being fully saturated with water vapor.
It is the ratio of water vapor pressure to saturation water vapor pressure expressed as a percentage.
%rh = (water vapor pressure/saturation water vapor pressure) * 100.0
Learn more about relative humidity and why it is measured for industries.
The two formulas differ in their applicable temperature ranges. The Hyland-Wexler formula is suitable for temperatures between -100°C and 0°C, whereas the Sonntag formula is valid for a broader range of temperatures, spanning from -80°C to +50°C. This wider temperature range makes the Sonntag formula more versatile and applicable to a greater variety of situations.
Humidity indicates moisture in the air, while dew point is the temperature at which moisture condenses. Relative humidity is the percentage of moisture in the air compared to its maximum capacity at a given temperature. These concepts help gauge comfort, condensation, and moisture conditions.
Learn more about these consepts
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The term “humidity” is often interchangeable with “relative humidity,” but there’s a significant difference between these two terms in the context of precise measurement.
Reviewing the laws of physics that govern water vapor in a moist gas can help you better understand the properties of what you’re measuring.
A change in the total pressure of a gas mixture, at constant composition, results in the same change in the partial pressure of each component.
Vapor concentration or absolute humidity of a mixture of water vapor and dry air is defined as the ratio of the mass of water vapor Mw to the volume V occupied by the mixture.
Saturation vapor pressure depends only on temperature. There is no effect of total pressure, and there is no difference between the situation in an open space and that in a closed container.
The capacitive humidity sensor consists of a hygroscopic dielectric material placed between a pair of electrodes that forms a small capacitor.