Nortec NHTC, NHPC manual Grains of Water Per Cubic Foot Saturated Air 100% rh, Incoming AIR Volume

Table 3. Grains of Water Per Cubic Foot – Saturated Air (100% rh)

°C	°F	Grains	°C	°F	Grains	°C	°F	Grains	°C	°F	Grains	°C	°F	Grains	°C	°F	Grains
-23	-10	.29	4	40	2.86		58	5.41		76	9.75	35	95	17.28		114	29.34
	-5	.35		41	2.97		59	5.60		77	10.06		96	17.80		115	30.13
-18	0	.48		42	3.08	16	60	5.80		78	10.40		97	18.31	49	120	34.38
	8	.61		43	3.20		61	6.00		79	10.80		98	18.85		125	39.13
-12	10	.78		44	3.32		62	6.20	27	80	11.04		99	19.39	54	130	44.41
-9	15	.99	7	45	3.44		63	6.41		81	11.40	38	100	19.95		135	50.30
-7	20	1.24		46	3.56		64	6.62		82	11.75		101	20.52	60	140	56.81
-4	25	1.56		47	3.69	18	65	6.85		83	12.11		102	21.11		145	64.04
-1	30	1.95		48	3.83		66	7.07		84	12.49		103	21.71	66	150	72.00
	31	2.04		49	3.97		67	7.31	29	85	12.87		104	22.32		155	80.77
	32	2.13	10	50	4.11		68	7.57		86	13.27	41	105	22.95	71	160	90.43
	33	2.21		51	4.26		69	7.80		87	13.67		106	23.60		165	101.00
	34	2.29		52	4.41	21	70	8.10		88	14.08		107	24.26	77	170	112.60
2	35	2.38		53	4.56		71	8.32		89	14.51		108	24.93		175	125.40
	36	2.47		54	4.72		72	8.59	32	90	14.94		109	25.62	82	180	139.20
	37	2.56	13	55	4.89		73	8.87		91	15.39	43	110	26.34		185	154.30
	38	2.66		56	5.06		74	9.15		92	15.84		111	27.07	88	190	170.70
	39	2.76		57	5.23	24	75	9.45		93	16.31		112	27.81		195	188.60
										94	16.79		113	28.57

(2)Formula 2

Assume our printing plant is located in Denver, Colorado. From Table 4, the worst case is -10°F with 37% rh

From Table 3:

0.29 gr/ft3 x 37% rh - 0.11 gr/ft3

Combining this result with that of Moisture Required (A) we see that we will need

5.19 - 0.11 = 5.08 grains of moisture for every cubic foot of outside air brought in.

E.INCOMING AIR VOLUME

(1)The following outlines the steps necessary to determine the amount of outside air being brought into the humidified space and the corresponding amount of moisture required. There are three basic means by which outside air is introduced into the humidified space. These are:

(a)Through natural ventilation, for example, opening and closing doors and windows, and by infiltration through cracks and openings in the building construction.

(b)Through mechanical ventilation, for example, the introduction of make-up air, or the exhausting of stale air by the building HVAC system.

(c)Through the economizer section of the HVAC system - if this feature is included in the system.

(2)For maximum accuracy, all three should be estimated and the largest chosen.

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Page 15 2008-10-01