Patent ID: 7059367

Claim:
A liquid level maintaining device for monitoring the surface level of a body of liquid held by a reservoir and controllably supplying make-up liquid from a liquid source to maintain the surface level of the body of liquid at a set level in the reservoir, said liquid level maintaining device comprising: a flow path between the liquid source and the reservoir, the make-up liquid being biased to flow from said liquid source along said flow path to the reservoir; flow restricting means for restricting the make-up liquid to a desired volumetric flow rate as the make-up liquid flows along said flow path; a pilot with a pressure sensing port and a pressure transmitting passageway filled with a gas, said pilot being secured to maintain said port at a fixed level relative to the reservoir, said fixed level being below the surface level of the body of liquid, and said gas being in pressurized communication with a surface of the liquid; a pilot controlled sequence valve having a liquid inlet, a liquid outlet, a control chamber and a pressure activated valve mechanism movable between open and closed positions, said control chamber being in pressure transmitting communication with said gas in said pressure transmitting passageway, and said valve mechanism moving to its said open position to open a pathway between said inlet and outlet when said control chamber is below a predetermined pressure, and moving to its said closed position to close said pathway when said control chamber is at least equal to said predetermined pressure; and, wherein the sequence valve moves to said open position and the make-up liquid flows from the liquid source to the reservoir when the surface level of the body of liquid drops to a lower level, and said sequence valve moves back to its said closed position when the surface level of the body of liquid rises to the set level.