GB346240A - Improvements in and relating to pressure measuring apparatus - Google Patents

Abstract

346,240. Liquid-level vacuum gauges. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Hardy, C. V. ; 36, Ray Street, and Johnston, P. J. ; 2141, Plaza, both in Schenectady, New York, U.S.A.) July 15, 1930, No. 21439. Convention date, July 18, 1929. [Class 106 (ii).] In a liquid vacuum gauge comprising a plurality of liquid containing tubes terminated by a cylinder i n t o which a plunger is forced to move the liquid. into a pressure reading position, a chamber, communicating with the cylinder, prevents spilling of liquid when the plunger is improperly operated. The envelope containing the rarefied gas is connected to the tube 15, the gas entering the tubes 13, 14, 12, 10, 11 the mercury evel being normally below the junction of the tubes 10, 12 which are connected by tubes 8, 7, 6 to a cylinder or pipe 4 open to the atmosphere and which is fitted with a plunger 18. When the latter is depressed, the column of gas in the tubes 10, 11 is separated from that of the envelope and the pressure may be determined by comparing the heights of the respective liquid columns on a scale 16. To prevent spilling of the mercury over the top of the pipe 4 when the plunger 18 is depressed too quickly or when there is not a substantial vacuum in the envelope a chamber 20 is fitted to the pipe 4 the mercury flowing therein through openings 21, Fig. 4.