How do you size a dryer for your air compressor? Some air compressor systems include an air treatment package built-in. For those that don’t – you can select from a desiccant filter/dryer unit, or cycling and non-cycling refrigerated air dryers. It is not complicated, but at the same time there are a few thumb-rules that come into consideration.

Ambient Temperature, Inlet Temperature, and Pressure must be considered.

Most often, you can assume 100°F Ambient Temperature, 100°F Inlet Temperature to the Dryer (aka discharge of the compressor), and 100psi.

If your air compressor can put out 50cfm, you need at least 50 cfm of capacity in your air dryer. It is important to note that your dryer is then already at max capacity. Those key factors like high ambient temperature will reduce the capacity of your dryer, depending on how much drying capability is required. It should make sense – if you are running equipment during the hot and humid month of August in a place like Florida, your dryer is going to be pulling gallons upon gallons of condensate out of that air. If your dryer is undersized, your air will be out of spec and you will be sending water down your discharge piping!

It is common practice to run a dryer that has a capacity 15-30 cfm higher than your compressor.

Don’t forget to install an Oil / Water Separator to easily remove oil from discharged condensate right at the source! Otherwise, it is against local and federal regulation to discharge oily water down the drain, and costly to contract out the treatment of thousands of gallons of oily water..