The Technology of Cooling Part 1: Cooling with Filterfans®

If the installation is in a clean, non-hazardous environment with an acceptable ambient (outside the enclosure) temperature range, a simple forced-air cooling system utilizing outside air is usually adequate. Combined with an air filter, such devices generally meet the heat removal needs of typical electronic equipment and many electrical applications. 

How do I know if a Filterfan® is the right product for my application?

  • If the temperature rise inside the enclosure can be higher than the ambient
  • If multiple configurations are needed. Filterfans® can be located in a number of locations within complex enclosure configurations.

Calculating the required airflow

To properly size a Filterfan® it’s important to understand how static pressure effects the performance of a fan.

Understanding CFM

CMF describes the volume flow rate of compressed air. We can define 3 different CFM:

  • CFM1: Fan Only (unfiltered)
  • CFM2: Filterfan® Assembly (uninstalled)
  • CFM3: Filterfan® Installed on an enclosure with one filtered exhaust assembly
    (Note: Always calculate cooling capacity of Filterfans® with the CFM3 value)

Utilizing Filterfans® for Enclosure Cooling 

  • Always use the Filterfans® to propel the cool ambient air into enclosure.
  • Slight positive pressure builds up inside the cabinet so that only air filtered by the Filterfans® flows into the enclosure.
  • The air propelled into the cabinet displaces the warm air which exits through the exhaust filter.
  • When installing a combination of Filterfans® and exhaust filters, fit the Filterfans® in the lower third of the cabinet and the exhaust filter(s) near the top of the cabinet.

Utilization examples

CFM : Filterfan® + Exhaust Filter CFM : Filterfan® + 2 Exhaust Filters CFM : Filterfan® + intake + Filterfan® Exhaust


Part 1 of our Thermal Management Solutions, Pfannenberg’s Filterfans® incorporate modern louvers which enable maximal airflow, hold back dust/flour and water particles, protect the filter medium from damage and can be integrated into the design of the application. Filterfans are an ideal cooling solution when the ambient air is always lower than the temperature required in the electrical enclosure. This assists the natural convection of the air and avoids hot spots withing the enclosure.

Pfannenberg is the inventor of the Filterfan®, with 50 years of experience and continuous development. Trust in the Original

Read the 2nd part of our Thermal Management Tips: Cooling with Closed Loop Air to Air Heat Exchangers