Document Ev7N5vdj88j9d8wYnXXQq0Oj4

/ andAmerican Society of Heating Ventilating Engineers Guide, 1929 boiler or furnace smoke-pipe is attached. The boiler or furnace smoke-pipe shall be thoroughly grouted into the chimney and shall not project beyond the inner surface of the flue lining. The size or area of flue lining or of brick flue for warm-air furnaces depends on height of chimney and capacity of heat ing system. For chimneys not less than. 35 ft. in height above grate line, the net internal dimensions.of lining should be at least 7 x 1134 in. for a total leader pipe area up to 790 sq. in. Above 790 and up to 1000 sq. in. of leader.pipe area the lining should be at least 1134 x 1134 in. inside. In case of brick flues not less than 35 ft. in height with no linings, the internal, dimensions should be at least; 8 x 12 in. up to 790 sq. in. of leader area, and at least 12 x 12 in. for leader capacities up to 1000 sq. in.. Chimneys under 35 ft. in height are unsatisfactory in operation and hence should be avoided. SMOKE TEST The chimney flue shall be subjected to a smoke test by the mason contractor in the presence of the architect or his representative, after the mortar has thoroughly hardened, and must be smoke tight. The method of conducting this test shall.be as follows: With a good fire in the boiler or furnace, or in the base of the chimney, put about a square yard of tar paper on the fire. As soon as smoke appears at'the top of the chimney close the top of the flue with a piece of old carpet or wet newspapers held down, by a weighted board. Keep the tar paper burning in the firepot for five minutes. The architect or his represen tative shall sign an acceptance in triplicate, stating that the chimney was tight under the above test, and shall give one copy to the mason contractor, one copy to the heating contractor and one copy to the owner. 158 CHAPTER VII MECHANICAL DRAFT Data on Grates* Forced Dra/t, Induced Draft, Motor Driven Blowers* Steam Driven Blowers, Steam Jets, Stokers, Duct Work. THE subject of mechanical draft is divided into two main divisions-- forced draft and induced draft. Present day practice inclines towards forced draft for heating plants. The burning of the lower grades and the smaller sizes of coal necessitates strong drafts, which are frequently produced mechanically. The stack or chimney effect necessary to properly carry off the gases of combustion is sometimes produced by induced draft. With the type of installations considered in this chapter which relate particularly to the heating and ventilating field, forced draft installations predominate. The combination of both forced and induced draft is sometimes employed, but is usually confined to power stations where economizers, air heaters, etc. are installed. In order to give proper recommendations for mechanical draft, some thing should be said about the grates and furnaces. Table 1 gives the various styles of grates suitable for different fuels in boiler plants men tioned in this article. Table 1. Grates Suitable for Various Fuels and Boilers Kind of Fuel High Pressure Boilers High or Low Pressure Steel Boilers-- Firs Box Low Pressure Cast Iron Sectional High or Low Pressure Scotch Marine High or Low Pressure Upright Type of Air Openings and % Openings Domestic Anthracite Stationary or Shaking Shaking Shaking Shaking Shaking Herringbone Finger or Cross Rib 30% - 40% No. 1 Buckwheat Stationary or Dumping No. 2 Buckwheat No. 3 Buckwheat Screenings Stationary or Dumping Stationary or Dumping Dumping Dumping Dumping Dumping Dumping Dumping Stationary Stationary or Shaking or Dumping - Dumping Fine Herringbone Slotted or Pinhole 8% - 14% Stationary or Dumping Stationary ' Fine Slotted or or Pinhole Dumping 8% -12% Stationary or Dumping Stationary or Dumping - Fine Slotted or Pinhole ~ 8%-10% Run of Mine Bituminous Stationary or Shaking- Shaking Shaking Stationary or Shaking Stationary or Shaking . Herringbone or Cross Rib 30% - 40% The material for this Chapter prepared especially for The Guide by R. W. Pryor, Edgar Johnson and C. H. Smith. 159