Abstract
SOME useful observations on the action of safety valves on boilers have been recently communicated to the Vienna Academy by Herr von Burg (November 13). Among other things it is proved that the authoritative directions given in different countries as to the size of safety valves are not at all adequate, and are based on erroneous conceptions. As to the cause of the small amount of lifting of the valve during escape of steam (seldom over 1/2mm.), the author at first supposed a vibratory motion of the valve, but further study and experiment led him to the hypothesis that the steam jets, in lifting the valve, do not begin to move from its middle point, but from the periphery of a circle, ρ, out to the circumference of the valve of radius r; so that the pressure of steam on the under surface of the valve is composed of two parts, of which the inner, or aërostatic, is produced by the solid steam-cylinder of radius ρ, and the,outer or weak aërodynamic part, by the external hollow cylinder of r-ρ thickness of wall. The phases of development of steam tension, and other topics, are also investigated.
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Physical Notes . Nature 21, 189 (1879). https://doi.org/10.1038/021189a0
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DOI: https://doi.org/10.1038/021189a0