Nortec NHPC, NHTC manual Regain of Hygroscopic Materials, Still Air Double Windows, Wind

Table 5. Inside Relative Humidities At Which Moisture Will Condense On Windows (cont)

Outside			Inside Temperature (°F/°C)					Outside			Inside Temperature (°F/°C)
Temperature								Temperature
°F	°C	60/		65/	70/	75/	80/	°F	°C	60/		65/	70/	75/	80/
		15.5		18.3	21	23.8	26.6			15.5		18.3	21	23.8	26.6
Double	Windows,	Still Air						Double Windows, Wind
-50	-45	34		34	34	33	32	-50	-45	23		26	26	26	25
-40	-40	38		38	36	36	35	-40	-40	32		30	30	29	28
-30	-34	42		42	41	40	38	-30	-34	36		34	34	32	31
-20	-29	47		46	46	44	42	-20	-29	41		39	38	35	35
-10	-23	52		50	49	48	46	-10	-23	46		45	42	42	39
0	-18	57		55	55	52	50	0	-18	52		49	47	46	44
10	-12	62		60	59	57	54	10	-12	58		56	53	52	49
20	-7	69		66	63	62	59	20	-7	65		63	59	58	54
30	-1	76		73	71	68	65	30	-1	72		70	66	64	60
40	4	84		80	79	74	71	40	4	80		78	73	70	67

NOTE: Bold areas indicate that moisture will be in the form of frost on windows.

Table 6. Regain of Hygroscopic Materials

Industry	Materials				Relative Humidity - %
		10	20	30		40	50	60	70	80	90
Baking	Crackers	2.1	2.8	3.3		3.9	5.0	6.5	8.3	10.9	14.9
	Flour	2.6	4.1	5.3		6.5	8.0	9.9	12.4	15.4	19.1
	White Bread	0.5	1.7	3.1		4.5	6.2	8.5	11.1	14.5	19.0
Leather	Sole Oak, Tanned	5.0	8.5	11.2		13.6	16.0	18.3	20.6	24.0	29.2
Printing	Paper – Comm. Ledger – 75% Rag	3.2	4.2	5.0		5.6	6.2	6.9	8.1	10.3	13.9
	1% Ash
	Paper M.F. Newsprint – 24% Ash	2.1	3.2	4.0		4.7	6.1	7.2	8.7	10.6
	Paper White Bond Rag – 1% Ash	2.4	3.7	4.7		5.5	6.5	7.5	8.8	10.8	13.2
	Paper Writing – 3% Ash	3.0	4.2	5.2		6.2	7.2	8.3	9.9	11.9	14.2
Textile	Cotton – Absorbent	4.8	9.0	12.5		15.7	18.5	20.8	22.8	24.3	25.8
	Cotton – American-cloth	2.6	3.7	4.4		5.2	5.9	6.8	8.1	10.0	14.3
	Cotton – Sea Isle-roving	2.5	3.7	4.6		5.6	6.6	7.9	9.5	11.5	14.1
	Hemp – Manila and Sisal	2.7	4.7	6.0		7.2	8.5	9.9	11.6	13.6	15.7
	Jute – Average Grade	3.1	5.2	6.9		8.5	10.2	12.2	14.4	17.1	20.2
	Linen – Dried Spun – Yarn	3.6	5.4	6.5		7.3	8.1	8.9	9.8	11.2	13.8
	Rayon – Celulose – Acetate – Fibre	0.8	1.1	1.4		1.9	2.4	3.0	3.6	4.3	5.3
	Rayon – Cupramonium – Average	4.0	5.7	6.8		7.9	9.2	10.8	12.4	14.2	10.0
	Skein
	Rayon – Viscose Nitrocel	4.0	5.7	6.8		7.9	9.2	10.8	12.4	14.2	16.0
	Silk – Raw Chevennes-Skein	3.2	5.5	6.9		8.0	8.9	10.2	11.9	14.3	18.8
	Wool – Australian-Marino-Skein	4.7	7.0	8.9		10.8	12.8	14.9	17.2	19.9	23.4
Tobacco	Cigarette	5.4	8.6	11.0		13.3	16.0	19.5	25.0	33.5	50.0
Wood	Timber – Average	3.0	4.4	5.9		7.6	9.3	11.3	14.0	17.5	22.0
	Glue – Hide	3.4	4.8	5.8		6.6	7.6	9.0	10.7	11.8	12.5
Miscellaneous	Charcoal-Steam Activated	7.1	14.3	22.8		26.2	28.3	29.2	30.0	31.1	32.7
	Gelatin	0.7	1.6	2.8		3.8	4.9	6.1	7.6	9.3	11.4
	Silica Gel	5.7	9.8	12.7		15.2	17.2	18.6	20.2	21.5	22.6
	Soap	1.9	3.8	5.7		7.6	10.0	12.9	16.1	19.8	23.8
	Starch	2.2	3.8	5.2		6.4	7.4	8.3	9.2	10.6	12.7

NOTE: Moisture content expressed in per cent of dry weight of the substance at various relative humidities – Temperature 75°F.

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