Vented Enclosures - Understanding Your Vent Options

Our homes and vehicles almost always come equipped with ventilation devices to help circulate air, equalize pressure and remove moisture. Whether it’s as simple as a window or as complex as air conditioning, ventilation makes our lives safer and more comfortable. 

Many electronic and electrical device enclosures have a similar need for ventilation. The devices that electrical enclosures protect often generate significant levels of heat. Moisture can also accumulate inside electronics enclosures, so it’s important to have electrical enclosure vents that allow it to escape. 

Use this short guide to ventilated enclosures to get familiar with all the key basics of enclosure ventilation–from calculating your enclosure’s heat levels to the different types of ventilation available. We’ll also talk about the most important electronics enclosure air vent accessories available from Polycase. 

Polycase Air Vent

Does My Enclosure Need to Be Ventilated? 

If the device components inside your electronics enclosure generate any significant amount of heat, it’s likely that your enclosure will need some kind of ventilation. Large devices that generate high levels of heat will usually require an engineered mechanical ventilation solution designed specifically for that device and enclosure. Smaller devices with lower input power can often take advantage of surface area dissipation, heat sinks and various passive venting strategies.

To find out whether your enclosure should be vented, you’ll first need to ascertain the level of heat rise that will occur inside. To do this, you’ll find your device’s input power and use a sealed enclosure temperature rise graph to determine its level of temperature increase. For easy step-by-step instructions on using one of these graphs, read our guide to calculating sealed enclosure temperature rise. 

When calculating your enclosure’s temperature rise and ventilation needs, be sure to consult with the engineering and manufacturing staff responsible for the device in question. Through their specialized knowledge, they can provide a more sophisticated picture of your device’s heat dissipation needs. 

Passive vs. Forced Air Ventilation

There are two major categories of enclosure ventilation: passive and forced air. 

• Passive ventilation uses non-mechanical design elements, such as ventilation holes cut into the enclosure, to cool the device, equalize pressure and prevent condensation. Passive ventilation is typically used for ventilating smaller device enclosures with lower input power. 
• Forced air ventilation uses mechanical methods, such as blower fans, to actively circulate and cool the air in the enclosure. Forced air is often required for large devices with high input power and can be much more complex than passive ventilation.  

For maximum efficacy, either ventilation method can be paired with other heat dissipation methods, including heat sinks and enclosure finishes that increase surface area dissipation. 

If passive ventilation is sufficient for your application, several types of ventilation may suit your needs. Louver vents are among the most popular built-in ventilation types, as their slanted design provides some protection from dust and liquid ingress. However, many venting accessories are also available to create air circulation in your enclosure without compromising its integrity. 

Polycase Vent Plug

Enclosure Venting Devices from Polycase

Polycase is a leader in industrial and commercial electronic device enclosures. Although Polycase’s enclosures don’t come with built-in vents, we offer several types of enclosure venting devices that can help control heat and moisture inside your enclosure:

• Vent Plug: An ideal choice for letting air escape without letting anything in. Our vent plugs use an integral sealing ring and ultrasonically welded filter membrane to create an advanced liquid tight seal, while a series of small holes allow airflow for ventilation. They are NEMA 4X/IP68 rated. 
• Cable Gland: Many device enclosures need spaces for cables to enter and exit, but these spaces can create an access point for moisture and dirt. Cable glands form a liquid- and dust-tight seal around a cable and prevent moisture and particulates from entering. Available with ratings up to NEMA 6P/IP68.
• Cable Seal: These rubber sealing membranes are easy to adjust for various cable sizes by cutting them with a standard utility knife. Available in a variety of sizes and IP55 rated. 
• Standard Air Vent: ABS plastic air vents suitable for indoor applications. 
• Outdoor Air Vent: Polycarbonate plastic air vents suitable for outdoor applications. Available in 60mm and 80mm sizes. Compatible with most enclosure ventilation fans. 
• Hooked Air Vent: ABS plastic air vents with a J-shaped design, suitable for indoor applications. 

Polycase also offers custom CNC machined cutouts on many of our enclosure models. These cutouts make it quick and easy to outfit your electronics enclosure with ventilation devices. It’s simple—just send us a CAD file of your required cutouts and our state-of-the-art precision CNC machining will do the rest. Alternatively, our SK Series enclosures are polycarbonate NEMA 4X  and IP66 rated “knockout boxes” that come equipped with pre-cut knockouts for easy attachment of venting accessories. 

Polycase SK-13 enclosure with pre-cut knockouts

Need some advice on proper enclosure ventilation? Polycase’s enclosure experts will be glad to help. Just contact us online or call us at 1-800-248-1233 for more information.