June 3, 2022
Sizing Your Air-Dryer (SCFM vs ACFM)
While Zorn Compressor is equipped with tons of experts to properly size all your compressed air equipment to your applications, we understand you may want to have an understanding yourself of what size air dryer to get and why! This is especially important for cost savings and efficiency in these warmer summer months where we observe increased moisture in our operations.
SCFM & ACFM- WHAT ARE THEY AND WHY DO I CARE?
CFM stands for cubic feet per minute.
SCFM stands for standard cubic feet per minute.
ACFM stands for actual cubic feet per minute.
Starting with SCFM: various countries and regions may have varying conditions they consider “standard.” In the United States you can remember our standard conditions by the number 100. We see 100 psig inlet air pressure, 100°F inlet air temperature, 100°F ambient air temperature, and 100% relative humidity to be standard conditions for your compressed air equipment.
In reality, standard conditions are not always met, so ACFM was created to account for the maximum airflow your dryer can dry after adjusting to the actual operating conditions your compressor is working in. This also means that the ACFM of a dryer may not always match the SCFM and that is OK!
So, to be prepared for the changing conditions your compressor may encounter, you should be sizing your dryer based on ACFM.
CHANGING ENVIRONMENTAL FACTORS & THEIR EFFECTS
We touched on the relationship with these environmental factors and your dryers briefly in our last blog post so this should serve as a review and introduce another way to understand how the changing environmental factors will affect your air dryer.
All the below factors are taken into account with the given correction factors for your machine, this is just to provide some insight to the logic behind the calculations that go into sizing your dryers.
TEMPERATURE
Any change in temperature will have an inverse effect on your dryer’s ACFM. There are two types of temperature to account for: inlet and ambient.
INLET
Inlet temperature is the temperature of the air as it enters into the dryer. In general, every 20°F increase in inlet air temperature can double the moisture load on the dryer. The higher the inlet temperature, the lower the drying capacity. This is due to the fact that the warmer air is holding more moisture, so the dryer needs to work harder to remove more moisture.
AMBIENT
Ambient temperature is the temperature of the air surrounding your system. Like inlet temperature, the higher the temperature the lower the drying capacity. However, this only works directly for refrigerated air dryers as it has less of an effect of desiccant air dryers.
PRESSURE
Pressure has the inverse effect that temperature has. An increase in pressure means a decrease in moisture content. Therefore, the higher the pressure the inlet air pressure, the less your air dryer needs to work to remove moisture from the air, thus increasing your dryer’s drying capacity. Air moves slower as air pressure increases so it has a longer time to be in contact with the dryer.
HUMIDITY
Relative humidity does not play a huge role in changing your air dryer’s efficiency. Under most conditions, air will already be at 100% humidity when it reaches the dryer.
INCREASE EFFICIENCY WITH THESE RELATED AIR DRYER PARTS:
WATER SEPARATORS
- Installed before the dryer
- Removes liquid from the compressors
PRE-FILTER
- Installed before the dryer
- Prevents and reduces particulate entering the system
POST FILTER
- Installed after the dryer
- Helps remove oil
3-VALVE BYPASS
- Installed around the filters & dryer
- Preventative part to assist in servicing and maintenance needs
ZORN'S PROMISE
Zorn is the Midwest leader of custom, engineered compressed air and vacuum solutions. We provide the best customer experience by understanding your applications and needs and offering an unparalleled commitment to customer satisfaction.
Our comprehensive product and service solutions keep you running 24/7.
- Reliable equipment
- Trusted brands
- Seamless, easy installation
- Post-sales support
- Local, 24/7 service
Our compressed air experts look forward to meeting you to discuss your equipment and support needs. Please contact us directly at (262) 695-7000 with any questions or to schedule service for your system moving forward.
Related Resources
- Compressed Air Applications in Water Treatment & Wastewater Treatment
- Going Green with Variable Speed Drive Controls
- Defining Compressed Air Quality
- The Cost of Compressed Air
- Compressed Air Applications in the Glass Industry
- Traveling & Compressed Air
- What Makes My Air Compressor So Noisy?
- Leak Detection Case Study
- Effects the Cold Weather Can Have on Your Compressed Air System
- Designing the Perfect Compressor Room