Water Vapor Air
Reference data and engineering information about water vapor air for air psychrometrics applications.
watervaporair
Overview
Engineering reference data for Water Vapor Air in air psychrometrics.
Key Formulas
Humidity Ratio
Mass of water vapor per mass of dry air.
Relative Humidity
Ratio of actual to saturation vapor pressure.
Wet Bulb Temperature
Temperature measured by wet-bulb thermometer.
Enthalpy of Moist Air
Sensible + latent heat per unit mass of dry air.
Variables
| Symbol | Description | Unit |
|---|---|---|
| Humidity ratio | kg/kg | |
| Relative humidity | % | |
| Vapor pressure | Pa | |
| Saturation vapor pressure | Pa | |
| Dry bulb temperature | °C | |
| Wet bulb temperature | °C |
Data Tables: Moisture Content in Air
The following tables provide the weight of water vapor in moist air at standard atmospheric pressure, presented in two common engineering units.
Grains of Water Vapor per Pound of Dry Air
Note: 1 grain = 0.000143 lbm = 0.0648 g (7000 grains per lbm).
8 rows
Temp (°C) | Temp (°F) | RH 10%(gr/lb) | RH 20%(gr/lb) | RH 30%(gr/lb) | RH 40%(gr/lb) | RH 50%(gr/lb) | RH 60%(gr/lb) | RH 70%(gr/lb) | RH 80%(gr/lb) | RH 90%(gr/lb) |
|---|---|---|---|---|---|---|---|---|---|---|
| -1 | 30 | 3 | 5 | 7 | 9 | 12 | 14 | 17 | 19 | 21 |
| 4 | 40 | 4 | 7 | 11 | 14 | 18 | 22 | 26 | 29 | 33 |
| 10 | 50 | 6 | 10 | 14 | 20 | 26 | 32 | 38 | 42 | 48 |
| 16 | 60 | 8 | 16 | 22 | 30 | 39 | 48 | 54 | 62 | 70 |
| 21 | 70 | 11 | 21 | 34 | 44 | 55 | 66 | 78 | 88 | 100 |
| 27 | 80 | 16 | 30 | 46 | 62 | 78 | 92 | 108 | 125 | 140 |
| 32 | 90 | 21 | 42 | 65 | 85 | 108 | 128 | 152 | 173 | 190 |
| 38 | 100 | 29 | 58 | 87 | 116 | 147 | 176 | 208 | - | - |
Source: engineeringtoolbox.com
Pounds of Water Vapor per Pound of Dry Air
8 rows
Temp (°C) | Temp (°F) | RH 10%(lbw/lba) | RH 20%(lbw/lba) | RH 30%(lbw/lba) | RH 40%(lbw/lba) | RH 50%(lbw/lba) | RH 60%(lbw/lba) | RH 70%(lbw/lba) | RH 80%(lbw/lba) | RH 90%(lbw/lba) |
|---|---|---|---|---|---|---|---|---|---|---|
| -1 | 30 | 0.0004 | 0.0007 | 0.001 | 0.0013 | 0.0017 | 0.002 | 0.0024 | 0.0027 | 0.003 |
| 4 | 40 | 0.0006 | 0.001 | 0.0016 | 0.002 | 0.0026 | 0.0031 | 0.0037 | 0.0041 | 0.0047 |
| 10 | 50 | 0.0009 | 0.0014 | 0.002 | 0.0029 | 0.0037 | 0.0046 | 0.0054 | 0.006 | 0.0069 |
| 16 | 60 | 0.0011 | 0.0023 | 0.0031 | 0.0043 | 0.0056 | 0.0069 | 0.0077 | 0.0089 | 0.01 |
| 21 | 70 | 0.0016 | 0.003 | 0.0049 | 0.0063 | 0.0079 | 0.0094 | 0.0112 | 0.0126 | 0.0143 |
| 27 | 80 | 0.0023 | 0.0043 | 0.0066 | 0.0089 | 0.0112 | 0.0132 | 0.0154 | 0.0179 | 0.02 |
| 32 | 90 | 0.003 | 0.006 | 0.0093 | 0.0122 | 0.0154 | 0.0183 | 0.0217 | 0.0247 | 0.0272 |
| 38 | 100 | 0.0041 | 0.0083 | 0.0124 | 0.0166 | 0.021 | 0.0252 | 0.0297 | - | - |
Source: engineeringtoolbox.com