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NFPA 86 Excess Temperature Interlock Requirement

Question asked by rajeev.limaye on Sep 16, 2020

NFPA 86 states " 8.16.3   Operation of the excess temperature limit interlock shall cut off the heating system before the oven's maximum temperature, as specified by the oven manufacturer, is exceeded."

Does the excess temperature here refer to the flue gas temperature? What if the shutdown is implemented on the process fluid outlet temperature instead of the flue gas temperature? Is it acceptable to have the interlock based on the high process fluid (the fluid being heated in the furnace in enclosed pipes) temperature instead of the flue gas temperature?

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