Patent ID: 7587940
Filing Date: 2009-09-15
Classification: G01F,G01L

Abstract:
1. A liquid level sensor, comprising: a hollow member having a distal open end adapted to be positioned into a liquid reservoir to a depth below a liquid surface level, the distal open end of the hollow member allowing liquid to enter the tube to an equilibrium level dependent on the volume of liquid in the liquid reservoir; a sensor head unit configured for mounting at a head mount location remote from the liquid reservoir; a connection tubing system adapted to provide a closed fluid conduit between the hollow member at the liquid reservoir and the sensor head unit at the head mount location, such that an air column pressure in said hollow member dependent on said equilibrium level is transmitted to the sensor head unit; said sensor head unit comprising a non-electrically powered system for providing an indication of a position of said liquid surface level, said system including: a flow restrictor positioned to dampen instantaneous differential column pressure changes presented to the bellows member while permitting steady state column pressure to be communicated to the bellows member.