. American engineer and railroad journal . suppose there are 45 lbs. of water evaporatedat a pressure of 12 atmospheres from each square-foot of heat-ing surface per hour, wherein the temperature of the steam is375° F.; with pure water and a clean plate the temperature ofthe plate becomes 400 + 160 = 560° F. ; with .04 in. of + 160 = 630° F. ; with .12 in. of scale, 570 + 160 = 730°P. ; and for .2 in. of scale, 840 + 160 - 1,000° F., which would continuously. The lower dotted line gives the tensile strengthof copper, which drops to zero at about 1,110° F. Let us now take foran exampl
. American engineer and railroad journal . suppose there are 45 lbs. of water evaporatedat a pressure of 12 atmospheres from each square-foot of heat-ing surface per hour, wherein the temperature of the steam is375° F.; with pure water and a clean plate the temperature ofthe plate becomes 400 + 160 = 560° F. ; with .04 in. of + 160 = 630° F. ; with .12 in. of scale, 570 + 160 = 730°P. ; and for .2 in. of scale, 840 + 160 - 1,000° F., which would continuously. The lower dotted line gives the tensile strengthof copper, which drops to zero at about 1,110° F. Let us now take foran example our new four-wheels coupledhigh speed locomotive (fig. 4), where we have observed theexpansions lengthwise, acioss and vertically. According to the investigations of the Messrs. Lochner* atErfurt, the boiler, which only differs slightly from the so-called Erfurt boilers, evaporates from 12,000 lbs. to water per hour at a steam pressure of 12 atmospheres, andwhen running at a speed of from 31 miles to 56 miles in tlie. Fig. 4-BOILER FOR EXPRESS PASSENGER LOCOMOTIVE ON THE STATE RAILWAY OF HANOVER. be in the highest degree dangerous for copper, since, accordingto fig. 3, it has at that point a tensile strength of only about1,950 lbs. per square inch, while a copper crown-sheet will lay-claim to a shearing strength of the stay-bolt heads for a steampressure of 12 atmospheres, and even be grooved above thestay-bolts. And .2 in. of scale is not uncommon on a coppercrown sheet. From the ascertained temperature we are now to calculatethe expansion, which I take to be ^ for wrought iron and same time. Suppose we take for the following estimate only15,400 lbs. of steam produced per hour, and take the fire-boxas having 97 sq. ft. of heating surface, and the tubes 1,184sq ft., giving 7+ per cent, of the total beating surface to thefirst, and 92J per cent to the tubes. It will be seen, then, that,according to fig. 1, the fire box will evaporate 32 per cent, of * Organ
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