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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1908 edition. Excerpt: ... condition of the material itself. You can readily appreciate that a spring of brass would compress with less pressure than one of steel, similar in every other respect, and that there is such a wide difference in steels that there will be a great deal of difference in the action of steel springs according to the kind of metal, degree of temper, etc. The best rule known is the following: To f1nd at what pressure a valve will lift with a spring of given dimensions and compression: Multiply the compression in inches by the fourth power of the thickness of the steel in sixteenths of an inch, and by 22 for round or 30 for square steel. Product I. Multiply the cube of the diameter of the spring, measured from center to center of the coil (as on the line d, in Fig. 69) in inches, by the number of free coils in the spring, and by the area of the valve in square inches. Product II. Divide Product I by Product II and the quotient will ' be the pressure per square inch at which the valve will blow off. The weight of the valve and of the spring should in strictness be added to Product I, when the construction is such that the valve supports the spring; but inasmuch as the values 22 and 30 are guessed at it will not pay to go into ref1nements in other directions. The result of this rule has never been compared with an actual valve. It is based on a formula adopted by a committee of Scotch engineers and shipbuilders. Correspondence with the manufacturers of pop safety valves as to the accuracy of the formula brings out the fact that they proportion and calibrate their springs only by experience and experiment. However, this rule is given for what it is worth. If you have a springloaded valve calculate it by this rule and see how nearly it comes to the more

Product details

  • Paperback | 34 pages
  • 189 x 246 x 2mm | 82g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236605055
  • 9781236605054