GB190824674A - Improvements in Safety Valves. - Google Patents

Abstract

24,674. Mills, C. R. Nov. 17. Safety - valves. - A safety-valve for steam boilers &c. comprises a main valve having two valve heads 19, 20, the lower head 20 forming the obturating - member. The upper head, which is of the greater area, is situated in an inner chamber and divides the same into upper and lower compartments 21, 22. Situated at the top of the compartment 21 is a spring-loaded auxiliary valve 24, adjustable by means of a screw 36. The fluid pressure has direct access to the underside of the valve head 20 through the hollow connecting-stem 18 to the upper side of the head 19. When the pressure becomes excessive, it opens the auxiliary valve and puts the compartment 21 into communication with the atmosphere through the passage 23, the compartment 22, the pin valve 40, and, the exhaust chamber 14 formed by the outer casing 9. The main, valve is thereby free to lift by fluid pressure underneath, and the excess pressure is relieved through the passages 13 and the exhaust chamber 14. The auxiliary valve has a large and a small area, the latter only being exposed to the boiler pressure when the valve is closed, but as soon as it is moved from its seat the larger area is exposed to pressure thereby causing it to be opened quickly so as to open the main valve promptly.