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Vapor Pressure of Water at DBT is the pressure exerted by water vapor which are in thermodynamic equilibrium with its condensed phases (solid or liquid) in a closed system at a given temperature.
The calculator uses the formula:
Where:
Explanation: This formula calculates the vapor pressure of water based on the saturation humidity value, using the constant 0.6207 which represents the ratio of molecular weights of water vapor to dry air.
Details: Accurate vapor pressure calculation is crucial for various applications including HVAC system design, meteorological studies, industrial processes involving humidity control, and environmental engineering.
Tips: Enter the saturation humidity value. The value must be non-negative. The calculator will compute the vapor pressure of water at dry bulb temperature.
Q1: What is saturation humidity?
A: Saturation humidity is defined as the absolute humidity of vapour-gas mixture at 100% saturation, representing the maximum amount of water vapor the air can hold at a given temperature.
Q2: What units are used for vapor pressure?
A: The vapor pressure is typically measured in Pascals (Pa) in the SI system, though other units like mmHg or atm may also be used in different contexts.
Q3: Why is the constant 0.6207 used in the formula?
A: The constant 0.6207 represents the ratio of molecular weights of water vapor (18.015 g/mol) to dry air (28.97 g/mol), which is essential for converting between humidity ratios and partial pressures.
Q4: What factors affect vapor pressure of water?
A: Vapor pressure primarily depends on temperature and the amount of water vapor present. It increases with temperature and with higher humidity levels.
Q5: How accurate is this calculation method?
A: This formula provides a good approximation for many engineering applications, though for precise scientific work, more complex equations that account for temperature variations and other factors may be necessary.