issue: May 2009 APPLIANCE Magazine
Appliance Engineer - Technology Report
Enclosures Breathe Easy
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Fire containment is achieved with a heat-responsive coating on honeycomb vent panels that have low airflow resistance under normal conditions.
The PyroCide vent panel from Universal Air Filter Co. (UAF; Sauget, IL, U.S.; www.uaf.com) is an aluminum-framed, aluminum honeycomb thermal barrier. It is treated with intumescent flame-retardant coating that expands rapidly upon exposure to fire or excessive heat, filling the honeycomb cells with foam. This effectively eliminates airflow and stops flames from spreading. “The PyroCide coating has an ASTM E-84 Class A rating with low flame spread and low smoke index values. It can help engineers comply with flame spread requirements of industry standards,” says Dan Krupp, director of sales and engineering.
Under normal operating conditions, UAF says, the PyroCide provides more than 95% open area for negligible resistance to airflow within an electronics cooling chassis, thus allowing thermal engineers to maximize cooling air. “Unlike other competitive products previously available, the PyroCide intumescent coating does not creep or swell slightly when exposed to normal elevated temperatures over an extended time period,” says Krupp.
UAF tackled the creeping problem by formulating the new coating. “The flame-retardant formula has been tested in environmental test chambers,” says Mike Miano, engineering and sales manager at UAF. “So the panels do not reveal signs of creeping and can last several years in the equipment application.”
The design of the vent panel itself also helps optimize the airflow. “The edge-to-edge designs incorporate a low-profile frame to maximize the open airflow area for cooling air at the edges of the frame,” says Miano. Moreover, “in applications with cooling air fans, the airflow can become turbulent. The vent panel can help create a baffle to promote evenly distributed airflow and laminar airflow from the vent panel exhaust,” adds Miano.
Compared with other fire break panels, according to UAF, the PyroCide vent panel offers more flexibility. It can be designed to any dimension and various thicknesses to meet customer specifications and facilitate easy access and removal. “Previously, thermal or mechanical design engineers were restricted to rigid fire containment designs that prevented access to the electronics card cage,” Krupp tells APPLIANCE. The products can also be configured with EMI gaskets, hole patterns, spring clips, and other attachment hardware to improve installation and contact.
A custom vent panel can be designed to be compatible with the product’s enclosure. Precision metal fabricated framed vent panel assemblies can be created in 3-D CAD and integrated into intricate customer enclosure designs. UAF offers a free prototype service at www.uaf.com, so designers can evaluate a sample for form, fit, and function before placing the order. Once the prototype is submitted, it is produced and shipped within five working days.