Furnace Explosions Recent furnace explosions serve as a reminder that boilers must be maintained and operated in strict compliance with the manufacturers' recommendations. A furnace explosion is usually the result of ignition and instantaneous combustion of highly flammable gas, vapor, or dust that has accumulated in a boiler. The effect of the force from the explosion is often much greater than the boiler combustion chamber can withstand. Minor explosions, commonly know as deflagration, puffs, flarebacks, or blowbacks, may suddenly blow flames from firing doors and observation ports. Anyone in the path of a flame, which might extend many feet, may be seriously burned. An increase in the intensity of the explosion would naturally increase the probability of a serious accident. Furnace explosions may be avoided by taking reasonable precautions: Ensure that fuel inlet valves on nonoperating burners and ignitors are tightly closed and do not leak. Purge the furnace in accordance with the manufacturer's specifications each time before the first burner is ignited. Ensure that the ignitors, fuel regulating controls, and flame safeguards operate as required. Ensure that the fuel/air ratio is in accordance with the manufacturer's specifications. Remove oil guns from idle burners after closing the oil and air or steam supply valves when shutting down oil burners. Drain and clean residual oil from the guns before storage. Never use the boiler's soot blowers to blow soot in a cold boiler. Ensure that limit and operating controls are in good working condition and are not "by-passed" or "jumpered-out." Proper operation, proper maintenance, and timely inspection are key elements in ensuring safe boiler operation. For more information contact the North Carolina Department of Labor, Boiler Safety Bureau.