Fuel
Oil Pressure Regulating Valve
Model #: 10255
The regulating valve controls pressure to 600 psi at the discharge side of a fuel oil pump. A rise in line pressure - which may be brought about by decreased fuel consumption at the furnace - opens the regulating valve to return excess fuel oil to the inlet side of the pump. An air pressure regulator sets the pneumatic loading signal to the upper diaphragm chamber. The resultant displacement of diaphragm and plate causes the spring to apply a corresponding force to the retainer. Valve stem therefore closes to throttle fuel oil fuel flow. If pressure at the inlet to the regulating valve increases, this pressure rise is transmitted through the connection from the valve body. to the chamber below the piston. The piston consequently rises threby raising the valve stem to allow for greater return flow through the valve. Manual loading of the diaphragm-spring-piston combination is possible by turning the handwheel clockwise after the nut had been loosened. For automatic operation, the handwheel must always be rotated fully counterclockwise.
