To understand the configurations for filterfans. Filterfans are a passive cooling unit that can be installed in different configurations to meet the customer’s needs.
Fan-In With a Single Exhaust
This is the standard configuration that is recommended for a standard application. It is a Filter Fan installed on the bottom of a cabinet with the Exhaust installed at the top of the cabinet. Preferably on opposite sides of the cabinet like in Figure 1 below.
Benefits
• A positive pressure is created in the cabinet which assists with keeping particulates from entering the enclosure from other small unseen openings the cabinet may have.
• The fan is not exposed to the warmer temperatures at the top of the cabinet
• Forced air into the bottom of the cabinet allows for a more developed turbulent flow of cooler
ambient air to cool electronics.
Drawbacks
• Forced air into the bottom of the cabinet can cause the creation of hotspots to occur near the top of the cabinet (this can be mitigated with the exhaust installed on opposite sides of the cabinet)
Fan-Out With a Single Exhaust
This configuration is a reverse flow Filter Fan installed on the top of a cabinet with the Exhaust installed at the bottom of the cabinet. Preferably on opposite sides of the cabinet like in Figure 2 below.
Benefits
• Forced air out at the top of the cabinet lowers the chance for hotspots to form
Drawbacks
• Negative pressure inside of the cabinet allowing for particulates to enter through unseen openings in the cabinet
• The fan motor is exposed to a higher temperature at the top of the cabinet
Fan-In With Two Exhausts
This configuration is similar to the Fan-In with a single exhaust but with the two exhausts. It is recommended to have the have the filter fan be installed at the bottom middle of the door with the exhausts being installed at the top on opposite sides from each other like in Figure 3
Benefits
• Increased CFM through the cabinet in comparison to a single exhaust due to a lower pressure build up inside of the cabinet
• A positive pressure is created in the cabinet which assist with keeping particulates from entering the enclosure from other small unseen openings the cabinet may have.
• The fan is not exposed to the warmer temperatures at the top of the cabinet
• Forced air into the bottom of the cabinet allows for a more developed turbulent flow of cooler ambient air to cool electronics
Drawbacks
• Lower pressure inside the cabinet (harder to overcome in tightly packed cabinets)
• Forced air into the bottom of the cabinet can cause the creation of hotspots to occur near the top of the cabinet (this can be mitigated with being installed on opposite sides of the cabinet
Fan-In With a Fan-Out
This configuration is a Filter Fan installed on the bottom of a cabinet with a reverse flow Filter Fan installed at the top of the cabinet. Preferably on opposite sides of the cabinet like in Figure 4 below.
Benefits
• Increased pressure system which results in a higher CFM through the cabinet compared to a fan-in with a single exhaust
• Can overcome a more tightly packed cabinet with minimal effect on the overall CFM
• Forced air into the bottom of the cabinet allows for a more developed turbulent flow of cooler ambient air to cool electronics
• Forced air out at the top of the cabinet lowers the chance for hotspots to form.
• Smaller temperature gradient inside of the cabinet due to increased internal velocity and more developed turbulent flow throughout the cabinet
Drawbacks
• Fan at the top of the cabinet is exposed to warmer air