GB1358765A - Fluid flow control device in particular for an oil valve - Google Patents

Abstract

1358765 Controls for burners CONTROLS CO OF AMERICA 7 Sept 1971 [15 Sept 1970] 41561/71 Heading F4T [Also in Division F2] A fuel valve 5 is controlled by a first thermal actuator 11 to prevent the valve rising above a low flow position, a second similar actuator 12 to allow the valve to rise towards a high flow position, and a thermostatic actuator 14 to adjust the valve between the two positions in accordance with ambient temperature. Each of the actuators 11, 12 consists of a rod of high thermal expansion metal heated by an electric heater, the rod 11 being connected by a simple lever 17 to a spring-loaded stop 21 to limit upward movement of the valve 5 and the rod 12 by a compound lever system 26 to an arm 26b to determine the maximum flow position. The actuator 14 is connected by capillary tubing 15a to a liquid-filled sensing bulb 15 and operates the valve through a lever 36, a spring-mounted probe 37 and a further lever 6. The lever 36 is also arranged to operate a switch S1 through a pair of levers 55 and 56. When the control is switched on, resistors R1 and R2 energize the rods 11 and 12 and an igniter I lights the burner which is provided with a bi-metallic flame sensor switch SB. Fuel flow is thus maintained at a low value until the switch SB opens to deenergize the rod 11 and allow the valve 5 to rise to a position determined by the thermostat. The rod 12 determining the maximum opening of the valve remains energized through a switch S2 which is closed when the rod 12 expands. Once the desired temperature has been reached, the thermostat opens the switch S1 and the control is closed down until both the flame sensor and thermostat switches SB and S1 are again closed. The control can also be closed down by turning a knob 46, for setting the thermostat to zero. To prevent an electrical supply failure from closing the valve, a manual lever 30 is used to latch the lever 26 in a raised position, the latch being released automatically when the supply is resumed.