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7. CORRECTION FACTORS
Where applicable, it should used correction factors to keep the performance of the dryer.
Ambient temperature
Example: An ADS 75 has a nominal duty of 75 scfm (127 m³/h). What is the maximum allowable flow through the dryer under the following operating conditions:
Each item of data has a corresponding numerical factor which multiplied by the design air flow is as follows:
61 scfm (104 m³/h) This is the maximum flow rate that the dryer can accept under these operating conditions.
Minimum std. air flow rate =
In order to select the correct dryer model the required flow rate is to be divided by the correction factors relating to above mentioned parameters:
Minimum std. air flow rate =
Therefore the model suitable for the conditions above is ADS 125 (125 scfm [212 m³/h] - nominal duty).
Correction factor for operating pressure changes:
psig
60
Inlet air pressure
barg
Factor (F1)
0.79
Correction factor for ambient temperature changes:
°F
°C
Factor (F2)
1.10
Correction factor for inlet air temperature changes:
°F
Air temperature
°C
Factor (F3)
1.11
Correction factor for DewPoint changes:
°F
38
DewPoint
°C
Factor (F4)
0.92
How to find the air flow capacity:
Air flow capacity = Nominal duty x Factor (F1) x Factor (F2) x Factor (F3) x Factor (F4)
Inlet air pressure = 120 psig (8 barg) Factor (F1) = 1.07
Ambient temperature = 105°F (40°C) Factor (F2) = 0.93
Inlet air temperature = 122°F (50°C) Factor (F3) = 0.65
Pressure DewPoint = 50°F (10°C) Factor (F4) = 1.25
Air flow capacity = 75 x 1.07 x 0.93 x 0.65 x 1.25 = 61 scfm (104 m³/h)
How to select a suitable dryer for a given duty:
Factor (F1) x Factor (F2) x Factor (F3) x Factor (F4)
Example: With the following operating parameters:
80
100
120
4
5.5
7
8
0.91
1.00
1.07
80
90
95
100
27
32
35
38
1.07
1.04
1.00
90
100
110
122
32
38
43
50
1.00
0.80
0.65
41
45
50
3
5
7
10
1.00
1.7
1.25
Design air flow
Design air flow = 100 scfm (170 m3/h) Factor (F1) = 1.07
Inlet air pressure = 120 psig (8 barg) Factor (F2) = 0.93
Ambient temperature = 105°F (40°C) Factor (F3) = 0.65
Inlet air temperature = 122°F (50°C) Factor (F4) = 1.25
Pressure DewPoint = 50°F (10°C)
100
1.07 x 0.93 x 0.65 x 1.25
57
140
160
180
203
10
11
12
14
1.13
1.18
1.23
1.27
105
110
115
203
40
43
45
14
0.93
0.83
0.70
1.27
130
160
180
203
55
11
12
14
0.53
1.18
1.23
1.27
140
160
180
203
10
11
12
14
1.13
1.18
1.23
1.27
= 124 scfm (211 m³/h)
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