Air Dryer sizing

Air dryers are rated at the world wide standard of 25° C ambient air temperature.

Remember that this is Australia so you will have to re-rate your air dryer for Australian conditions. eg. Typical ambient temperature where you site the air dryer will be 40° C on our warmest days.

In some models of air dryers this can mean that after all of the calculations are done, you may need to buy an air dryer that will handle double the flow of compressed air to that shown on the brochure.

The typical correction factors that are used to rate air dryers are:

• Nominal air dryer flow rate
• FC1 = Air pressure correction factor (typically most compressors operate at 7Bar)
• FC2 = Ambient air temperature (for the hottest working days of the year)
• FC3 = Air Dryer inlet temperature (generally 10° C above the ambient air temperature)
• FC4 = Load factor (Pressure dewpoint at which water vapour condenses to form water-typically we work towards a 3° C dewpoint which will remove most of the vapour from your compressed air.  Getting rid of more vapour from your compressed air is then done by using absorption air dryers which are another cost. You would only use a dessicant dryer if you have specialist needs to remove that vapour from the air).

Every Air Dryer brochure has different factors to calculate the air dryer size that you will need so we cannot give you a one off formula that will help you size your air dryer correctly.

Our range of Jupiter Air Dryers are built for Australian conditions have a calculation of:

Real Flow Rate = Nominal air dryer flow rate * FC1 * FC2 * FC3 * FC4

ie. Look at the table on our Jupiter-OMI brochure and if you have 10 Bar air compressor output, sized to 40° C ambient temperature, with a properly setup aftercooler on you compressor which will result in 10°C above the ambient = 50°C with a 3°C dewpoint.

The formula will be as follows:

• FC1 = 1.18 for a compressor system running at 10 Bar
• FC2 = 0.85 for ambient temperature of 40°C where the air dryer will be sited
• FC3 = 0.87 for air dryer inlet temperature (where the aftercooler is correctly sized)
• FC4 = 1.00 at 3°C at which we get most of the water to drop out of compressed air

Thus:

Real Air Dryer flow rate =Nominal air dryer flow rate from brochure * 1.18 * 0.85 * 0.87 * 1.00

                                 =Nominal air dryer flow rate from brochure * 0.87261

ie. In the example above the brochure rated air dryer is only capable of handling a flow of 87.261% of air flow shown in the brochure. 

What does all this mean? Upsize your air dryer to the hottest days conditions that you expect to operate in and you should have most of the condensate removed from your system.

  Brochure for Easy Dry Line