Specifications for Triple-Expansion Twin-Screw Propelling Engines, with Boilers & Auxiliary Machinery for Naval Academy Practice Vessel of about 800 T

by U.S. Bureau of Steam Engineering

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. 1889. ... 116. SAFETY-VALVES. Each boiler will have two 2 M-inch spring safety-valves placed as near the front of boiler as possible; the two valves to be in one case. Each valve will have a projecting lip and an adjustable ring for increasing the pressure on the valve when lifted; or an equivalent device for attaining the same result. They will be adjustable for pressure up to the test pressure; the adjusting mechanism to have an index to show the pressure at which the valve is set, and a lock to prevent tampering with the adjustment. The locks on all safety-valves will be alike. The springs will be square in cross-section, of first quality of spring-steel, and will be nickel-plated. They will be of such a length as to allow the valves to lift one-eighth of their diameters when the valves are set at i60 pounds pressure. They will have spherical bearings at ends, or be connected to the compression-plates in such a manner as to insure a proper distribution of pressure. They will be inclosed in cases so arranged that steam will not come in contact with the springs. The springcases will be so fitted that the valves can be removed without slacking the springs. The valve-stems will fit loosely in valves to bottom below the level of the seats, and to be so secured that the valves may be turned by a wrench or cross-bar on top of stem. The valves will be guided by wings below and in an approved manner above. The valves will be fitted with mechanism for lifting by hand from main deck and fire-rooms; the mechanism for each pair of valves to be such that the valves will be lifted in succession. All joints in the lifting-gear will be composition bushed. The outlet-nozzle will be in the base casting, so that the joint at the escape-pipe will not have to be broken when taking th...

26 pages, Paperback

Published February 4, 2012