GB461002A - Improvements in or relating to closed heating systems employing a circulating heating liquid - Google Patents

Abstract

461,002. Fluid-pressure servomotor-control systems. FARRER, J. O., and KOCH, E. A. J. July 4, 1935, No. 19131. [Class 135] [Also in Group XIII] In a liquid heating system comprising a generator or heater 1, flow and return pipes 2, 3 respectively, consumers 4, and a circu. lating-pump 5, the return pipe is provided with a throttle valve 6 the spindle of which is secured to a diaphragm 7, Fig. 2, loaded on its under side by a spring and exposed on its upper side to the pressure of a liquid the flow of which is controlled by a valve 10 disposed in a chamber having a connection 17 to a vessel containing liquid at a constant pressure. The valve 10 is attached to a diaphragm 12 exposed on its upper side through a pipe 14 to the pressure on the delivery side of the pump, and on its under side, which is loaded by a spring, to the pressure on the suction side of the pump. When the suction pressure falls due to reduced flow, the valve 10 opens and admits liquid to the upper side of the diaphragm 7 thus effecting movement of the valve 6 towards its closed position. The space above the diaphragm 7 is provided with a leak orifice 19. By the above arrangement, a constant pressure differential is maintained between the suction and delivery sides of the pump. In a modification, the valve 10 is also controlled by a second diaphragm 24, Fig. 4, subjected on its opposite sides to the pressures on theopposite sides of an orifice plate 26 in the flow pipe.