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Burner Flame Detector

Uses Heat-Resistant, Dimensionally Stable Plastics

High heat resistance and dimensional stability are the main reasons Eclipse Combustion, Inc., Rockford, IL, selected polyphenylene sulfide (PPS) plastic to make a key component of its new furnace burner flame scanner. The high-sensitivity scanner detects UV radiation produced by the burner flame, converting UV light to a control signal for the burner's operation. Located on the burner assembly, the scanner can be exposed to temperatures up to about 250°F.

The compact sensor assembly consists of a small circuit board inserted into aluminum housing, which is sealed on both sides. The flame-viewing end of the scanner has a quartz lens in a housing made of glass fiber-reinforced PPS, which screws into the aluminum body. The housing is 0.725-in. in diameter and 0.78-in. long, and is pigmented black to ensure that no extraneous light enters the scanner. A stainless steel ring holds the quartz lens in place. The reinforced PPS provides dimensional stability over the range of temperatures to which the part is exposed, and the part has excellent resistance to long-term thermal embrittlement.

Eclipse Combustion machines the lens housing from glass fiber-reinforced PPS rod made by DSM Engineering Plastic Products, Rockford, IL. This material, which DSM makes by compression molding, has a continuous use temperature of 425°F and a very low coefficient of thermal expansion. Machining is the most economical method for making the PPS housing. Also, the close tolerance of the threaded end of the PPS housing and other design factors contribute to its being machined rather than injection molded.

--KC

For more information, contact: DSM Engineering Plastic Products, 2120 Fairmont Avenue, PO Box 14235, Reading, PA 19612-4235. 800-366-0310. Circle 469.

Eclipse Combustion, 1665 Elmwood Road, Rockford, IL 61103. 815-877-3031. Circle 456.