Document zo66oaN1Q3b1XR8p1QJY9mjjm

426 Chapter 17 = . .. . 1953 Guide In! such installations a definite, chimney:draft may be required for proper combustion, and consequently the foregoing reference to the use of; draft hoods \yould,not apply. . ...... , The: products of complete combustion of gas.are water .vapor (HiiO) and carbon dioxide (C02). In the case of: manufactured gas, the-presence - of: organic.sulfur compounds, generally .between 3 and 15 grains per hun dred cubic feet, gives rise to minute percentages of sulfur dioxide-and-sulfur trioxide; .The volume of water .vapor in the flue products from! natural or coke oven gas is about twice the volume of carbon dioxide. -It is extremely important that the chimney be tight and resistant to corrosion, not only from moisture,, but also from dilute sulfur trioxide. Clay linings with joints which prevent retention of moisture and lin ings made ofi non-corrosive. materials, are advantageous.' The protection of unlined chiinrieys has been .investigated and the results, indicate that Fig. 11, Capacity op a Rectangular Flue or. a Semi-Elliptical Floe, with-Semi-Circular Ends Having Its Minimum Width Equal to the Diameter of a Circular FlUe, Compared with the Capacity- op the Circular Flue after the loose material has been removed, spraying with,a water emulsion : of asphalt chromate will provide excellent protection. Advice regarding recommended practice and materials for flue connec tions and chimney linings can. usually be obtained from the local gas com pany, and should be given careful consideration. RECOMMENDATIONS OF THE NATIONAL-BOARD OF FIRE UNDERWRITERS . For general data, on, the construction of chimneys, reference should be made to the National Building Code, recommended by the National Board of Fire Underwriters, Article X, Section lOOl.to 1006, in which the following are some of the important provisions listed in the 1951 edition: 1. Flue Connections Required. Every heating apparatus or heat producing ap pliance requiring a flue connection shall be connected with a flue conforming to the provisions of this article. -: This shall not include electric appliances; gas appliances, except as specifically required in this.article; or oil fired appliances especially-de signed for .use without flue connection. .. , . - .2. Use of Nonconforming Flues. Flues not conforming, to the requirements of this article for chimneys, metal smokestacks or vents for gas appliances, shall.not .Chimneys and Draft Calculations . 427 be used unless listed by Underwriters' Laboratories, /nc.,installed'in full compliance with the listing.and the manufacturer's instructions, and approved for such use by the building official. 3. Smoke Pipe Connections. '- , , -. a. No flue shall have smoke pipe connections in more than one story.of a building, unless provision is made for effectively closing smoke pipe openings with devices made of noncombustible materials whenever their use is discontinued, temporarily, and completely closing them with masonry when discontinued permanently: .' b. Two or more smoke pipes shall not be joined for a single connection, unless the smoke pipes and flue are of sufficient size to serve all the appliances thus con nected. ................. . c. The smoke pipe of a heating appliance shall not be connected into the flue of an incinerator which has the rubbish chute identical with the smoke flue. 4. Construction of Chimneys. .. a. Chimneys hereafter erected, within or attached to a structure shall be con structed in compliance with the provisions of this section. b. Chimneys shall extend at least 3 ft above the highest point where they pass through the roof of the building, and at least 2 ft higher than any ridge within 10 ft of such chimney. ... c. Chimneys shall be wholly supported on masonry or self-supporting fireproof construction. d. No chimney shall be corbeled from a wall more than 6 in.; nor shall a chimney be corbeled from a wall which is.less than 12 in. in thickness, unless it projects equally on each side of the wall; provided that in the second story of 2-story dwellings cor beling of chimneys on the exterior of the enclosing walls may equal the wall thickness. In every case the corbeling shall not exceed 1 in. projection for each course, of brick projected. e. No change in the size or shape of a chimney, where the chimney passes through the roof, shall be made within, a distance of 6 in. above or below the roof joists.or rafters. 5. Chimneys for Heating Appliances, Low Heat lndustrial Appliances and Portable Type Incinerators. a. Chimneys for stoves, cooking ranges, warm air, hot water and low pressure steam heating furnaces, fireplaces, and low heat industrial appliances, other than chimneys for incinerators of nonportable type, shall be constructed of solid masonry units or of reinforced concrete. The. walls shall be properly bonded or tied with corrosion-resistant metal anchors. In dwellings and buildings of like heating re quirements, the thickness of the chimney shall be not less than 4 in. In other build ings the thickness shall be not less than 8 in., except that rubble stone masonry shall be not less than 12 in. thick. b. Every such chimney hereafter erected or altered shall be lined, with a flue lin ing conforming to the requirements below. . c. Flue linings shall be made of fire clay.or other refractory clay which will with" stand the action of flue gases and resist', without softening or cracking, the tempera- . tures to which they will be subjected, but not-less than 2000 F. Flue linings may be of cast iron of approved quality, form and construction. ,: - d. Required clay flue linings shall be not less than f in. thick for the smaller flues, and shall increase in thickness for the larger flues. e. Flue linings shall be installed ahead of the construction of the chimney as it is carried up, carefully bedded one on the other in Type A, Type B, or fire clay mortar with close fitting joints left smooth on the inside. f. Flue linings shall start from a point not less than 8 in. below the intake, or, in the case of fireplaces, from the throat of the fireplace. They shall extend, as nearly vertically as possible, for the entire height of the chimney, and be extended 4 in. above the top of cap of the chimney. g- Cleanouts for flues or fireplaces shall be equipped with cast-iron doors and frames arranged to remain tightly closed when not in use. h. When two or more flues are contained in the same chimney, at least every third flue shall be separated by masonry at least 4 in. thick bonded into the masonry wall'