Air Humidifying with Steam - Imperial Units

The amount of vapor (lb/h in 100 cfm) in humid air

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 (oF)	Humidity (%)
	100	85	80	75	70	65	60	55	50	45	40	35	30
90	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	1.67	1.42	1.33	1.25	1.17	1.09	1	0.92	0.83	0.75	0.67	0.58	0.5
20	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	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	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	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	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

Example - Humidifying Air with Steam

How much steam is needed to transform air at 30^oF with 100% humidity to air at 70^oF and 40% humidity?

In air at 30^oF and 100% humidity, the steam content is 1.67 lb/h (100 cfm/h air flow).

At air 70^oF 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.

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