Sheet 4979-1 Page 2
The duct section at the burner should be restricted with a curtain or silhouette plate at the discharge end of the burner to give a velocity of about 3500 feet per minute, which will cause a pressure drop of about 0.75"w.c. Installation. The Oven Zephyr can be installed in a horizontal or vertical duct, upstream or downstream of the fan. The burner should be in a section of duct where air flow is reasonably straight. Sharp turns, obstructions, or dampers immediately upstream or downstream of the burner must be avoided. A minimum of 5 duct diameters straight duct before the burner is recommended without inlets, mixing baffles, or other restrictions. The burner arrangement should promote evenly heated air. Use sections that will form a continuous flame approximating the duct cross section. A curtain or silhouette plate should be located flush with the discharge end of the burner. The plate should be bolted, rather than welded, to the duct walls, to allow some adjustment after installation. No part of the burner should be less than 2" from the curtain or less than 4" from the duct wall. Every 3' of burner arrangement should be supported. Long lengths can be supported by steel straps fastened to the bolts at burner flanges (with narrow edge of straps facing air flow). End castings are provided with ¾ " fpt tapped holes that can be used for supports. Access doors should be provided to permit inspection and ser- vicing of the burner. Sight ports or windows are required for observation of the pilot and main flame.
TABLE 1. Minimum % fresh make-up air requirements, assuming no moisture content.
temperature rise 100 degrees (F)
minimum make-up air
11% 22% 29% 36%
200 300 400
Practical, durable construction. Burner air baffles are made with large openings to reduce deposition of airborne material.
The burner body is made of sturdy cast iron for good temperature service. Sheet metal parts are heat-resistant aluminized steel. The burner can be used in air streams up to 500°F (upstream air). The temperature rise across the burner should not exceed 400°F, regardless of the inlet temperature. 4979 Oven Zephyrs are available in a variety of shapes to permit assembly in a configuration that will provide uniform heat distribution in the duct. See Table 2.
Flame Supervision. The burner endplate has provision for mounting a flame rod or UV scanner.
Two ignition methods are available: The burner can be lighted with a gas pilot or with a direct spark electrode.
Air velocity. The Oven Zephyr is designed for use in air streams having a uniform velocity of 1000 to 1500 feet per minute, and for best operation, air velocity should be constant.
TABLE 2. Burner sections
4979-12 4979-12-B
straight, 12"
(1 000 000 Btu/hr) (1 000 000 Btu/hr) (1 000 000 Btu/hr) (1 000 000 Btu/hr)
straight, 12", 2 ½ " bottom inlet
elbow, 6" 6"† elbow, 6" 6"†
4979-12-LI 4979-12-LO
4979-FEP 4979-SEP
main gas endplate, 2" gas inlet, ignition, and flame rod connections pilot endplate, support, ignition, and flame rod connections
† Main flame is either on inside or outside of elbow. Order must specify which elbow is wanted. If in doubt, send sketch of layout.
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