GB921814A - Improvements in and relating to automatic water-feeding apparatus for steam boilers - Google Patents

Abstract

921,814. Fluid-pressure servomotor control systems; valves. S.T.E.G.U. SOCIETE ANONYME. Sept. 30, 1959 [Sept. 30, 1958], No. 33221/59. Class 135. [Also in Group XIII] The rate of supply of feedwater to a boiler is regulated according to the water level therein by a steam pressure actuated valve 17 which receives steam through a line 16 from a vessel 1 connected by pipes 2, 2a, to the steam and water spaces of the boiler so that the level therein and in the vessel are the same. The vessel 1 contains a float 3 which is suspended by a lazytongs linkage 6 . . . 9 from fixed pivots 10, the uppermost links 9 being extended beyond the pivots to engage a pin secured to a pusher rod 12 which engages a conical valve 14 urged towards its closed position by a spring 13 housed in a chamber 15 from which branches the line 16. The pressure in the line 16 which corresponds to the amount of opening of the valve 14 is indicated by means of a gauge 22. An expansion chamber 19 is also connected to the chamber 15 and serves to damp the fluctuations in pressure inside the chamber. The float 3 contains a measured amount of distilled water 31, the evaporation of which under working conditions generates an internal pressure which at least partially offsets the steam pressure on the float allowing the latter to be made of thinner metal so that it floats higher in the water and is thus more sensitive to level variations.