Handbook for heating and ventilating engineers . imum. Long radius bends at the corners re-duce this friction. Offsets are especially valuable to takeup the expansion and contraction of the piping without theaid of expansion joints. This is illustrated in Fig. 108, whereanchors are placed at A, and the gradual bending of thepipes at each corner makes the necessary allowance. Theexpansion in wrought iron is about .00008 inch per foot perdegree rise in temperature; hence in a hot water main thelinear expansion between 0° and 212° is .017 inch per foot oflength or inches for each 100 feet of
Handbook for heating and ventilating engineers . imum. Long radius bends at the corners re-duce this friction. Offsets are especially valuable to takeup the expansion and contraction of the piping without theaid of expansion joints. This is illustrated in Fig. 108, whereanchors are placed at A, and the gradual bending of thepipes at each corner makes the necessary allowance. Theexpansion in wrought iron is about .00008 inch per foot perdegree rise in temperature; hence in a hot water main thelinear expansion between 0° and 212° is .017 inch per foot oflength or inches for each 100 feet of straight pipe. Inhot water heating systems, however, the temperature of thispipe would never be less than 50°, which would cause anexpansion from hot to cold of only .013 inch per foot, inches for each 100 feet of straight pipe. In a steammain the temperature may vary anywhere from 50* to 300*.making a linear expansion of .02 inch per foot of length or 2Inches for each 100 feet of straight pipe. As here shown V.)o. DISTRICT HEATING 219. Fig. 108. movement from, the anchorat A toward B may be ab-sorbed by the swinging of thepipe about O. shouldtherefore be as long as possi-ble, say one full block, toavoid unduly straining thepipe at the joints. Allowing amaximum movement of 6inches for each expansion joint, the anchors would be spaced500 and 300 feet center to center respectively, for hot waterand steam mains. These figures would seldom be exceeded,and in some cases Wiould be reduced, the spacing dependingupon the type of expansion joint used. Ordinarily, 400 feetspacing would be recommended for hot water and 300 feetfor steam. If the city layout meets this value fairly well,then the expansion joints and anchors may be made toalternate with each other, one each to every city block. A few of the expansion joints in common use are shownin I ig. 109. A is the old slip and packed joint. This jointcauses very little trouble except that it needs repackingfrequently. It i
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectventila, bookyear1913
