Humidifying Air with Steam - SI units

The amount of vapor - kg per cubic meter - in humid air

The table below can be used to estimate the amount of vapor in 100 m3 air volume.

Vapor in Air (kg per 100 m3airflow)
Dry Temperature (oC) Relative Humidity (%)
100 85 80 75 70 65 60 55 50 45 40 35 30
32 3.39 2.89 2.72 2.55 2.38 2.19 2.04 1.93 1.7 1.53 1.36 1.19 1.02
31 3.22 2.73 2.57 2.41 2.25 2.1 1.93 1.77 1.61 1.45 1.29 1.13 0.97
30 3.05 2.59 2.44 2.29 2.13 1.97 1.83 1.67 1.52 1.37 1.22 1.07 0.91
29 2.89 2.45 2.31 2.17 2.02 1.88 1.73 1.59 4.45 1.3 1.16 1.01 0.87
28 2.73 2.32 2.19 2.05 1.91 1.78 1.64 1.5 1.37 1.23 1.1 0.96 0.82
27 2.59 2.2 2.07 1.94 1.81 1.68 1.55 1.42 1.29 1.16 1.03 0.91 0.78
26 2.45 2.08 1.96 1.83 1.71 1.59 1.47 1.34 1.22 1.1 0.97 0.86 0.73
25 2.31 1.97 1.85 1.73 1.62 1.5 1.39 1.27 1.16 1.04 0.93 0.81 0.69
24 2.19 1.86 1.75 1.64 1.53 1.42 1.31 1.2 1.09 0.98 0.87 0.77 0.66
23 2.06 1.76 1.63 1.55 1.45 1.34 1.24 1.14 1.03 0.93 0.83 0.72 0.62
22 1.95 1.66 1.56 1.46 1.36 1.27 1.17 1.07 0.98 0.88 0.78 0.68 0.59
21 1.84 1.56 1.47 1.38 1.29 1.2 1.1 1.02 0.92 0.83 0.74 0.67 0.55
20 1.74 1.48 1.39 1.3 1.22 1.13 1.04 0.98 0.87 0.78 0.69 0.61 0.52
19 1.63 1.39 1.31 1.23 1.15 1.06 0.98 0.9 0.82 0.74 0.65 0.57 0.49
18 1.54 1.31 1.24 1.16 1.08 1 0.93 0.85 0.77 0.69 0.62 0.54 0.46
17 1.45 1.24 1.16 1.09 1.02 0.94 0.87 0.8 0.73 0.65 0.59 0.51 0.44
15 1.29 1.1 1.03 0.97 0.9 0.84 0.77 0.71 0.66 0.58 0.52 0.45 0.39
10 0.94 0.8 0.76 0.71 0.66 0.61 0.57 0.52 0.47 0.43 0.38 0.33 0.28
0 0.49 0.41 0.39 0.37 0.34 0.32 0.29 0.27 0.24 0.22 0.2 0.17 0.15
-5 0.33 0.28 0.26 0.25 0.23 0.21 0.2 0.18 0.16 0.15 0.13 0.11 0.1
-10 0.22 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.06

Note! In psychrometric charts and Mollier diagram the amount of vapor is given in kg/kg dry air. The values from the table above can be transformed dividing by the air density at the actual temperature.

Example - Humidifying Air with Steam

Air at 20oC and 30% relative humidity are humidified to 20oC and 80% relative humidity.

From the table above it can be estimated that air at 20oC and 30% relative humidity contains 0.52 kg water vapor per 100 m3 air flow. Air at 20oC and 80% relative humidity contains 1.39 kg per 100 m3 air flow.

The amount of water vapor can be calculated like

Amount of Water Vapor = ((1.39 kg) - (0.52 kg))

= 0.87 kg

is the amount of water vapor necessary for an air volume of 100 m3.

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