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Engineering ToolBox > Air Humidifying with Steam - Imperial Units
The table below can be used to calculate the amount of steam needed to humidify 100 cfm (cubic feet per minute) air.
| Vapor in 100 cfm air (lb/h) | ||||||||||||||
| Dry Temperature | Humidity (%) | |||||||||||||
| (oF) | (oC) | 100 | 85 | 80 | 75 | 70 | 65 | 60 | 55 | 50 | 45 | 40 | 35 | 30 |
| 90 | 32.2 | 12.84 | 10.92 | 10.26 | 9.6 | 9 | 8.34 | 7.68 | 7.08 | 6.42 | 5.78 | 5.14 | 4.49 | 3.85 |
| 88 | 31.1 | 12.06 | 10.26 | 9.66 | 9.06 | 8.46 | 7.87 | 7.26 | 6.66 | 6.06 | 5.41 | 4.82 | 4.22 | 3.62 |
| 86 | 30.0 | 11.4 | 9.66 | 9.12 | 8.52 | 7.98 | 7.38 | 6.85 | 6.3 | 5.7 | 5.13 | 4.56 | 3.99 | 3.42 |
| 85 | 29.4 | 11.04 | 9.36 | 8.82 | 8.28 | 7.74 | 7.2 | 6.6 | 6.06 | 5.52 | 4.97 | 4.42 | 3.86 | 3.31 |
| 84 | 28.9 | 10.68 | 9.06 | 8.52 | 7.98 | 7.5 | 6.96 | 6.42 | 5.87 | 5.34 | 4.81 | 4.27 | 3.74 | 3.2 |
| 83 | 28.3 | 10.38 | 8.82 | 8.34 | 7.8 | 7.26 | 6.72 | 6.24 | 5.71 | 5.19 | 4.67 | 4.15 | 3.63 | 3.11 |
| 82 | 27.8 | 10.08 | 8.58 | 8.04 | 7.56 | 7.08 | 6.54 | 6.06 | 5.54 | 5.04 | 4.54 | 4.03 | 3.53 | 3.02 |
| 81 | 27.2 | 9.78 | 8.34 | 7.8 | 7.32 | 6.84 | 6.36 | 5.87 | 5.38 | 4.89 | 4.4 | 3.91 | 3.42 | 2.93 |
| 80 | 26.7 | 9.48 | 8.04 | 7.56 | 7.08 | 6.66 | 6.18 | 5.69 | 5.21 | 4.74 | 4.27 | 3.79 | 3.32 | 2.84 |
| 79 | 26.1 | 9.18 | 7.8 | 7.32 | 6.9 | 6.42 | 5.96 | 5.51 | 5.05 | 4.59 | 4.13 | 3.67 | 3.21 | 2.75 |
| 78 | 25.6 | 8.88 | 7.56 | 7.08 | 6.66 | 6.24 | 5.77 | 5.33 | 4.88 | 4.44 | 3.99 | 3.55 | 3.11 | 2.66 |
| 77 | 25.0 | 8.64 | 7.32 | 6.9 | 6.48 | 6.06 | 5.62 | 5.18 | 4.75 | 4.32 | 3.89 | 3.46 | 3.02 | 2.59 |
| 76 | 24.4 | 8.4 | 7.14 | 6.72 | 6.3 | 5.88 | 5.46 | 5.04 | 4.62 | 4.2 | 3.78 | 3.36 | 2.94 | 2.52 |
| 75 | 23.9 | 8.1 | 6.9 | 6.48 | 0.06 | 5.67 | 5.26 | 4.86 | 4.48 | 4.05 | 3.64 | 3.24 | 2.83 | 2.43 |
| 74 | 23.3 | 7.86 | 6.66 | 6.3 | 5.89 | 5.5 | 5.11 | 4.72 | 4.32 | 3.93 | 3.53 | 3.14 | 2.75 | 2.36 |
| 73 | 22.8 | 7.62 | 6.48 | 6.12 | 5.71 | 5.33 | 4.95 | 4.57 | 4.12 | 3.81 | 3.43 | 3.05 | 2.66 | 2.29 |
| 72 | 22.2 | 7.38 | 6.3 | 5.9 | 5.53 | 5.17 | 4.79 | 4.43 | 4.06 | 3.69 | 3.32 | 2.95 | 2.58 | 2.21 |
| 71 | 21.7 | 7.14 | 6.06 | 5.71 | 5.35 | 4.99 | 4.64 | 4.29 | 3.93 | 3.57 | 3.21 | 2.86 | 2.5 | 2.14 |
| 70 | 21.1 | 6.9 | 5.86 | 5.52 | 5.17 | 4.84 | 4.48 | 4.14 | 3.79 | 3.45 | 3.1 | 2.76 | 2.41 | 2.07 |
| 69 | 20.6 | 6.72 | 5.71 | 5.38 | 5.04 | 4.7 | 4.37 | 4.03 | 3.7 | 3.36 | 3.02 | 2.67 | 2.35 | 2.02 |
| 68 | 20.0 | 6.48 | 5.51 | 5.18 | 4.86 | 4.54 | 4.21 | 3.89 | 3.55 | 3.24 | 2.92 | 2.59 | 2.27 | 1.94 |
| 67 | 19.4 | 6.24 | 5.3 | 4.99 | 4.68 | 4.37 | 4.06 | 3.74 | 3.43 | 3.12 | 2.81 | 2.5 | 2.18 | 1.87 |
| 66 | 18.9 | 6.06 | 5.15 | 4.85 | 4.54 | 4.24 | 3.94 | 3.64 | 3.33 | 3.03 | 2.72 | 2.42 | 2.12 | 1.82 |
| 65 | 18.3 | 5.87 | 4.99 | 4.7 | 4.4 | 4.11 | 3.82 | 3.52 | 3.23 | 2.93 | 2.65 | 2.35 | 2.06 | 1.76 |
| 60 | 15.6 | 4.97 | 4.23 | 3.98 | 3.73 | 3.48 | 3.23 | 2.98 | 2.74 | 2.48 | 2.24 | 1.99 | 1.74 | 1.49 |
| 55 | 12.8 | 4.19 | 3.56 | 3.35 | 3.14 | 2.93 | 2.72 | 2.51 | 2.31 | 2.09 | 1.89 | 1.68 | 1.47 | 1.26 |
| 50 | 10.0 | 3.52 | 2.99 | 2.82 | 2.64 | 2.47 | 2.29 | 2.11 | 1.94 | 1.76 | 1.58 | 1.41 | 1.23 | 1.06 |
| 45 | 7.2 | 2.95 | 2.51 | 2.36 | 2.21 | 2.06 | 1.92 | 1.77 | 1.62 | 1.47 | 1.33 | 1.18 | 1.03 | 0.89 |
| 40 | 4.4 | 2.45 | 2.09 | 1.96 | 1.84 | 1.72 | 1.6 | 1.47 | 1.35 | 1.22 | 1.1 | 0.98 | 0.86 | 0.74 |
| 30 | -1.1 | 1.67 | 1.42 | 1.33 | 1.25 | 1.17 | 1.09 | 1 | 0.92 | 0.83 | 0.75 | 0.67 | 0.58 | 0.5 |
| 20 | -6.7 | 1.07 | 0.91 | 0.85 | 0.8 | 0.75 | 0.7 | 0.64 | 0.59 | 0.53 | 0.48 | 0.43 | 0.37 | 0.32 |
| 10 | -12.2 | 0.67 | 0.56 | 0.53 | 0.5 | 0.47 | 0.43 | 0.4 | 0.37 | 0.33 | 0.3 | 0.26 | 0.23 | 0.2 |
| 0 | -17.8 | 0.41 | 0.35 | 0.32 | 0.31 | 0.29 | 0.26 | 0.25 | 0.22 | 0.2 | 0.19 | 0.16 | 0.13 | 0.12 |
| -10 | -23.3 | 0.25 | 0.21 | 0.2 | 0.19 | 0.17 | 0.16 | 0.15 | 0.14 | 0.12 | 0.11 | 0.1 | 0.08 | 0.08 |
| -20 | -28.9 | 0.14 | 0.12 | 0.11 | 0.11 | 0.1 | 0.1 | 0.08 | 0.08 | 0.72 | 0.06 | 0.05 | 0.05 | 0.04 |
How much steam is needed to transform air at 30oF with 100% humidity to air at 70oF and 40% humidity?
In air at 30oF and 100% humidity, the steam content is 1.67 lb/h (100 cfm/h air flow).
At air 70oF and 40% humidity, the steam content is 2.76 lb/h (100 cfm/h air flow).
The difference (2.76 - 1.67) = 1.09 lb/h is the amount of steam necessary for 100 cfm/h air flow.
This table neglects the sensible heat required to heat the cold air to the final state. In the example above the heat required to heat 100 cfm dry air from 30oF to 70oF must be added. The heat can be added as dry heat through some heating panels or similar, or in general more convenient by adding more steam.