TM 5-3895-374-24-2FLAME SAFEGUARDTest for Incandescent Refractory Hold-In with Photocell DetectorType 45CM 1 Photocell Scanners are actuated by light energy. To assure that the flame failure responsetime is not extended by radiation from incandescent refractory, the following test is recommended1.Operate the burner, following the burner manufacturer’s instructions, until the refractory is atmaximum operating temperature.2.Turn off the main fuel supply manually.3.Observe the display flame signal which must drop below 10 within 4 seconds.4.If the flame failure response time exceed 4 seconds, reduce the amount of light at the Photocell with ascreen, an orifice, or a filter lens, until the normal flame failure response is obtained.INSTALLATION - 69ND1 FLAME RODThe 69ND1 flame rod proves a gas pilot flame and/or main gas flame. It is a spark plug type unitconsisting of 1/2" NPT mount, a KANTHAL flame rod, a glazed porcelain insulating rod holder and a sparkplug connector for making electrical connections. The 69ND1 is available in 12," 18" or 24" lengths.The flame rod may be located to monitor only the gas pilot flame or both the gas pilot and main gasflames. It is mounted on a 1/2" NPT coupling.The following instructions should be observed:1.Keep flame rod as short as possible.2.Keep flame rod at least 1/2" from any refractory.3.Flame rod should enter the pilot flame from the side so as to safely prove an adequate pilot flameunder all draft conditions.4.If the flame is nonluminous (air and gas mixed before burning), the electrode tip should extend at least1/2" into the flame, but not more than half-way through.5.If the flame is partly luminous, the electrode tip should extend only to the edge of the flame. It is notnecessary to maintain absolutely uninterrupted contact with the flame.6.It is preferable to angle the rod downward to minimize the effect of sagging and to prevent it fromcoming in contact with any object.7.An adequate grounding surface for the flame must be provided. The grounding surface in actualcontact with the flame must be at least four times greater than the area of the portion of the flame rodin contact with the flame. It is essential to adjust the flame rod and ground area ratio to provide amaximum signal reading.Note: Interference from the ignition spark can alter the true signal reading by adding to, or subtracting from it. This trendsometimes may be reversed by interchanging the primary wires (line voltage) to the ignition transformer. This interferencecan also be reduced by the addition of grounded shielding between the flame rod and ignition spark.(page 3 - 1061)
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