Publisher's Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1900 edition. Excerpt: ... QUESTIONS FOR STATIONARY ENGINEERS. Engineers should also be prepared to answer any of the "Questions for Firemen." Q. What do you mean by the term "a one horse-power steam boiler"? A. A one horse-power boiler is one which would, under ordinary conditions, supply as much steam as would be consumed in an average steam engine producing-one horse-power. Q. Is there no more definite rating than this for the horse-power of boilers? A. Yes; generally, the horse-power of boilers is based on a capacity for evaporation of 30 pounds of water per hour from feed water at a temperature of 100 Fahr. to steam at a pressure of 70 pounds. Q. What is this method of rating called? A. It is known as the Centennial Rating, because it was determined upon by the Committee of Judges at the Centennial Exhibition in 1876. Q. Does the horse-power of steam boilers calculated according to this rule come near to the actual consumption of steam in ordinary steam engines? A. It is about right for an automatic cut-off, high-speed, non-condensing engine. For plain slide valve engines using a throttling governor the rating is much too low, while for compound and condensing engines it is too high. Q. In choosing a boiler, how would you determine upon the proper size, assuming that the horse-power is based upon the Centennial Rating? A. I would in any case have the boiler capacity somewhat in excess of that of the engine, because the evaporative power of the boiler will diminish with use owing to the accumulation of scale. Q. Is there any disadvantage in using a boiler larger than is strictly necessary to evaporate the necessary amount of steam? A. No; the efficiency of a boiler is not lessened by operating it below its maximum capacity, wherein the boiler differs..."
