Series LFF113-41, LFF1113-41 Pump Control Valve with Rate-of-Flow Feature is designed to minimize the surges associated with the starting and stopping of pumps, and automatically limit flow rate to a constant, adjustable, maximum. The valve opens at an adjustable rate upon pump start-up, and closes at an adjustable rate upon pump shut-off. When the valve is near closed a limit switch is tripped, turning the pump off. The pump starts and stops against a closed valve, and has provisions for manual operation in the event of power outages. Flow control throttling action is controlled by an externally mounted modulating control pilot, which senses differential pressure across a remote mounted orifice plate (field installed). The Orifice Plate is factory calibrated based upon minimum, maximum, and continuous flow rate requirements.