GB638245A - Improvements in or relating to steam supply control means for steamheated heat exchangers - Google Patents

Abstract

638,245. Fluid-pressure servomotor-control systems. COCKBURNS, Ltd., RODGER, J., and GRANT, T. Feb. 14, 1948, No. 4387. [Class 135] Steam supply control means for a steamheated heat exchanger, e.g a boiler feedwater heater, comprises a piston - controlled main valve for controlling the steam supply to the heater and a float-operated valve connected to the cylinder of the control piston of the main valve and which, on the accumulation of water in the steam space of the heater, opens and causes the main valve to close. The main valve has an inlet 23, Fig. 3, and an outlet 24, and steam passes from the inlet to the upper end of the cylinder 17 of the control piston 18 through a passage 25 and check-valve 26 and also to the lower end of the cylinder via a passage 27 having an adjustable needle-valve 28, the main valve being open when a pressure release connection 20 at the lower end of the cylinder 17 is closed. The connection 20 is connected to an inlet 29, Fig. 4, of the floatoperated valve, which comprises a balanced double-beat valve 15 connected to a float arm 34, the valve being normally closed, but opened to connect the inlet 29 with an outlet 35 communicating, e.g., with a condenser, on the accumulation of water in the float chamber which is connected to the steam space of the heater. A testing lever (not shown) is provided by which the valve 15 may be opened manually. The main valve is fitted with screw-down gear. An arrangement is described in which the floatoperated valve is duplicated, one float chamber being located slightly above the other and both valves being connected to the one main valve.