2.5 CORRECTION FACTORS
Correction factor for operating pressure changes :
Inlet air pressure barg 4 5 7 8 10 12 14
Factor (F1) 0.77 0.85 1.00 1.06 1.15 1.21 1.25
Correction factor for ambient temperature changes (Air-Cooled):
Ambient temperature ºC < 25 30 35 40 45
Factor (F2) 1.00 0.98 0.95 0.90 0.80
Correction factor for inlet air temperature changes:
Air temperature ºC < 30 35 40 45 50 55
Factor (F3) 1.20 1.00 0.85 0.75 0.61 0.49
Correction factor for DewPoint changes:
DewPoint ºC 3 5 7 10
Factor (F4) 1.00 1.09 1.18 1.38
How to find the air flow capacity: How to select a suitable dryer for a given duty:
Air flow
capacity
=
X
Factor
(F1)
Factor
(F2)
X
Factor
(F3)
X X
Factor
(F4)
Nominal
duty
Example: Example:
An RD 185 has a nominal duty of 18500
l/min. What is the maximum allowable flow
through the dryer under the following operating
conditions:
− Inlet air pressure = 8 barg
− Ambient temperature = 45°C
− Inlet air temperature = 50°C
− Pressure DewPoint = 10°C
Each item of data has a corresponding numerical
factor which multiplied by the design air flow is as
follows:
The procedure here is to list the operating
conditions and then to locate the
corresponding numerical factors:
− Design air flow = 16200 l/min
− Inlet air pressure = 8 barg
− Ambient temperature = 45°C
− Inlet air temperature = 50°C
− Pressure DewPoint = 10°C
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:
= 13206 l/min → This is the maximum
flow rate that the dryer can accept under these
operating conditions.
= 22693 l/min → Therefore the model
suitable for the conditions above is RD 250 (25000
l/min - nominal duty).
=
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