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Herrmidifier Load Calculator User Manual

Page 11

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L o a d C a l c u l a t i o n G u i d e

L o a d C a l c u l a t i o n G u i d e

11

w w w. h e r r m i d i f i e r- h v a c . c o m

SECTION III LOAD CALCULATIONS

Knowing that controlled humidification is needed is the first

step toward increasing productivity and cutting losses. The

second, and most important step, is to accurately deter-

mine the amount of moisture required to be added to the air

to reach the target R.H. level. A humidification project that

starts out with good intentions can fall flat because the de-

mand load was not calculated accurately and too little or too

much humidification equipment was installed. Following is a

simple, accurate guideline for determining your MAXIMUM

HUMIDIFICATION DEMAND LOAD. Help with calculating

this can be obtained by returning form I/C DI-5 to Herrmidi-

fier.

The Psychrometric Chart

All humidification calculations involve knowing the maxi-

mum amount of moisture a given quantity of air can hold at

saturation (100% R.H.), and being able, by calculations, to

compare this with the amount of moisture present and that

which is desired in that air. The amount of moisture in the air

is measured in grains per cubic foot. This figure is used in

calculations to eventually arrive at a demand load, in pounds

per hour, for the area to be humidified. The following Table

2-A shows the grains of moisture per cubic foot of air at spe-

cific temperature.

Table 2-A

°Fahrenheit

Grains

°Fahrenheit

Grains

-10

.29

52

4.41

-5

.37

53

4.56

0

.48

54

4.72

5

.61

55

4.89

10

.78

56

5.06

15

.99

57

5.23

20

1.24

58

5.41

25

1.56

59

5.60

30

1.95

60

5.80

31

2.04

61

6.00

32

2.13

62

6.20

33

2.21

63

6.41

34

2.29

64

6.62

35

2.38

65

6.85

36

2.47

66

7.07

37

2.56

67

7.31

38

2.66

68

7.57

39

2.76

69

7.80

40

2.86

70

8.10

41

2.97

71

8.32

42

3.08

72

8.59

43

3.20

73

8.87

44

3.32

74

9.15

45

3.44

75

9.45

46

3.56

76

9.75

47

3.69

77

10.06

48

3.83

78

10.40

49

3.97

79

10.80

50

4.11

80

11.04

51

4.26

81

11.40

82

11.75

107

24.26

83

12.11

108

24.93

84

12.49

109

25.62

85

12.87

110

26.34

86

13.27

111

27.07

87

13.67

112

27.81

88

14.08

113

28.57

89

14.51

114

29.34

90

14.94

115

30.13

91

15.39

120

34.38

92

15.84

125

39.13

93

16.31

130

44.41

94

16.79

135

50.30

95

17.28

140

56.81

96

17.80

145

64.04

97

18.31

150

72.00

98

18.85

155

80.77

99

19.39

160

90.43

100

19.95

165

101.00

101

20.52

170

112.60

102

21.11

175

125.40

103

21.71

180

139.20

104

22.32

185

154.30

105

22.95

190

170.70

106

23.60

195

188.60

There are basically three (3) humidification load factors and

two (2) humidification reduction factors:

HEATING LOAD: For desired R.H. at maximum indoor tem-

perature maintained when outdoor temperature is at mini-

mum heating design level.

COOLING LOAD: To replace moisture removed by conden-

sation from cooling process -- air conditioning and/or refrig-

eration.

PRODUCT LOAD: To condition product to final desired Re-

gain when received under other conditions. This load could

be plus or minus.

PROCESS REDUCTION: Moisture vapors emitted by pro-

cesses decrease humidification load.

PEOPLE REDUCTION: People give off 0.2 lbs. per hour

when seated; 0.9 lbs. per hour when active, thereby de-

creasing humidification load. We shall take a more, in depth,

look at these factors in this section.