Correction Factors
Compressed Air Products / How to choose a dryer / Correction Factors
CORRECTION FACTORS
The following operating conditions must be considered in every project: inlet air pressure, ambient temperature, inlet air temperature and pressure dewpoint. Each operating parameter has a corresponding numerical factor. A simple calculation between the air flow rate and the various factors defines the right dryer model to choose.
HOW TO FIND THE AIR FLOW CAPACITY?
Air flow capacity =
Nominal duty x (Factor F1 x Factor F2 x Factor F3 x Factor F4)
Example: An ACT 18 has a nominal duty of 108 m3/h. What is the maximum allowable flow through the dryer under the following operating conditions?
- Inlet air pressure = 8 barg Factor (F1) = 1.05
- Ambient temperature = 45°C Factor (F2) = 0.72
- Inlet air temperature = 50°C Factor (F3) = 0.59
- Pressure DewPoint = 10°C Factor (F4) = 1.37
Each item of data has a corresponding numerical factor which multiplied by the design air flow is as follows:
Air flow capacity = 108 x 1.05 x 0.72 x 0.59 x 1.37 = 66 m3/h
66 m3/h This is the maximum flow rate that the dryer can accept under these operating conditions.
HOW TO SELECT A SUITABLE DRYER FOR A GIVEN DUTY?
Minimum std. air flow rate =
Design air flow ÷ (Factor F1 x Factor F2 x Factor F3 x Factor F4)
Example: With the following operating parameters:
- Portata d’aria richiesta = 100 m3/h
- Design air flow = 100 m3/h
- Inlet air pressure = 8 barg Factor (F1) = 1.05
- Ambient temperature = 45°C Factor (F2) = 0.72
- Pressure DewPoint = 10°C Factor (F4) = 1.37
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 standard air flow rate = 100 : (1.05 x 0.72 x 0.59 x 1.37) = 164 m3/h
Therefore the model suitable for the conditions above is ACT 30 (186 m3/h - nominal duty).