Patent ID: 7043984

Claim:
An apparatus for measuring liquid levels relative to a bottom surface of a container such as an underground tank, comprising: an elongate frame having a lower end, an upper end and a passage extending lengthwise between the upper and lower ends; a float arranged in the passage in the frame so that the float is movable to rise to float in a liquid when the lower end of the frame contacts the bottom surface of the container; a float lock assembly mounted in the passage, the float lock assembly including: a float lock guide mounted to extend lengthwise in the frame and arranged to guide the float in lengthwise movement relative to the frame; a float lock actuator mounted in the passage to move the float laterally with respect to the frame as the lower end of the frame is moved away from the bottom surface of the container to lock the float in frictional engagement with the frame; a plurality of elastic members mounted to the float lock guide and arranged to provide a pressure against the float lock actuator to provide locking pressure between the float and the float lock actuator, the plurality of clastic members being further arranged to maintain the float lock guide and the float lock actuator in parallel relationship when the float is free to move relative to the frame to seek the liquid level; and wherein the frame has a lengthwise slot formed in an inner wall portion of a first side of the frame and wherein the float lock actuator is slidably mounted to the float lock guide such that the float lock actuator has a range of longitudinal motion in the frame and a range of lateral motion in the frame between a locked position in which a lower end of the float lock actuator extends beyond the lower end of frame and an unlocked position in which the lower end of the float lock actuator is displaced from the locked position toward the lower end of the frame, the float and float lock actuator being arranged such that lateral motion of the float lock actuator as it moves from the unlocked position to the locked position causes the float lock actuator to bring the float into frictional engagement with the frame to retain the float in position in the frame to indicate the liquid level.