Document LJ2Lbb1gM2pyYgq0y5zk3V0Yg

TO TA L LOSS IN FLUE GAS iN PER CENT 364 CHAPTER 14 1957 Guide tion of gas burning equipment.19 For installation of equipment burning other types of fuel, refer to the National Building Code of the N.B.F.U. 4. Certain additional precautions may be required for certain fuels (such as un diluted liquefied petroleum gas) and consequently provisions of local codes and other authoritative agencies should be followed. FUNDAMENTAL PRINCIPLES OF COMBUSTION Regardless of the type of fuel under consideration, its combustion results in the production of gaseous products. Many kinds of solid fuels contain minerals -which cannot be burned and are therefore left as a residue com monly called ash. Moreover, unless sufficiently high temperatures are employed and an ample supply of oxygen properly distributed is present, Fuels and Combustion 365 Fiq. 5. Illustration Showing Air Openings Necessary to Supply Air fob Combustion When Appliance is Installed in Confined Space A. Ventilating air outlet register for furnace room, 1 sq in. free area for each 1000 Btu per hr furnace input located above relief opening of draft hood# Register must not be blocked by drapes or other furnishings., B. Both registers must either face same large ventilated interior space or extend to such space by means of ducte. Vertical distance C/L to C/L of registers should be not less than 3 ft. . ,, .. _ C. Suggest room access door be not less than 6 ft high by a width sufficient to provide for installation or removal of furnace. At least 2 ft horizontal clearance should be provided in front of furnace when closet door is open, or 18 in. when door is closed. . ., ptJ1 D. Combustion and ventilation air inlet register for furnace room, 1 sq in. free area for each lWWiJw per hr furnace input, located at or below combustion air inlet to furnace. Register must not be blocked . / drapes or other furnishings. ...... . , ,;.*i E. Air circulated by furnace must be handled by ducts which are sealed to furnace casing and are entires separate from means provided for supplying combustion and ventilation air. . __ , . F. Spacing between draft hood and wall at least 6 in. (unless approved for closer spacing). If flue .produce ^ may be directed toward wall, 12 in. spacing recommended. .[ft G. No part of furnace waging closer than 6 in. to wall (unless approved for closer spacing). ." H. Flue should terminate above peak of roof and above nearby walls to assure satisfactory flue perio^* - ance. In installations where the flue terminal is below nearby walls or roof peaks, an effective vent <*% *. should be used. `V the combustible constituents of solid, liquid, and even gaseous fuels can- ; not be completely burned. Incomplete or partial combustion of all fuel? ^ produces toxic gases, such as carbon monoxide, with smaller quantities^ of aldehydes, ketones, and other hydroxylated hydrocarbon compounds^ . This fact indicates that, while combustion processes involving common,^ types of fuel may be regulated by experienced operators to produceth^ most efficient results, normal combustion processes can be so unbalanced, a? to create hazards unless both design and operation are planned with a knowji^:-. edge: of the fundamental principles of combustion. Combustion may be defined as the chemical combination of a substan^vS with oxygen resulting in the evolution of heat, and usually some light. rate of combustion depends upon the rate of reaction of the substance oxygen, upon the rate at which oxygen is supplied, and upon the tempera-^ TO TAL LOSS IN FLU E GAS IN PER CENT Anthracite Fuel Oil Fig. 6. Flue Gas Losses with Various Fuels* Flue Gas Temperature Shown. Loss is Based on 65 F Room Temperature.