Liquid level system

An apparatus for measuring the level of liquid in a tank comprising:

• (a) lower and upper sensors being adapated to be mounted adjacent to a relatively low liquid level and a relatively high liquid level, respectively, in a tank;
• (b) each said sensors comprising:
• (1) a rigid housing and first and second bellows;
• (2) said first bellows being mounted in said housing having a movable end spaced from the wall of said housing defining a chamber therebetween;
• (3) said second bellows being mounted on the exterior of said housing;
• (4) passageways providing flow communication between the interior of said second bellows and said chamber;
• (c) a conduit providing flow communication between the interiors of said first bellows;
• (d) a first liquid filling the interiors of said first bellows and said conduit;
• (e) a second liquid different from said first liquid filling the interiors of said second bellows and said chambers;
• and
• (f) means connected to one of said bellows for producing an electrical output signal proportional to the difference between the pressures at the respective locations of said two second bellows, said difference being a function of the level of liquid in the tank.

A liquid level system which may operate at a relatively high temperature and pressure comprising:

• (a) a tank having a relatively low liquid level and a relatively high liquid level;
• (b) lower and upper sensors mounted inside said tank adjacent to said relatively low liquid level and said relatively high liquid level, respectively;
• (c) each said sensor comprising:
• (1) first, second and third chambers;
• (2) a first movable pressure sensitive barrier separating said first and second chambers;
• (3) a fixed wall separating said second and third chambers;
• (4) said third chamber embodying a second movable pressure sensitive barrier exposed to the interior of the tank;
• (5) passageways providing flow communication between said second and third chambers;
• (d) a conduit providing flow communication between said first chambers of said lower and upper sensors;
• (e) a first liquid filling said first chambers and said conduit;
• (f) a second liquid different from said first liquid filling said second and third chambers of said lower and upper sensors;
• and
• (g) means connected to one of said second movable barriers for producing an electrical output signal proportional to the difference between the pressures at the respective locations of said second movable barriers, said difference being a function of the level of liquid in the tank.

An apparatus for measuring the level of liquid in a tank which may operate at a relatively high pressure and a temperature of about 650.degree. F. comprising:

• (a) lower and upper sensors being adapted to be mounted adjacent to a relatively low liquid level and a relatively high liquid level, respectively, in a tank;
• (b) each said sensor including a pressure sensitive diaphragm defining a chamber therein;
• (c) a conduit providing flow communication between said chambers of said lower and upper sensors;
• (d) a liquid filling said chambers and said conduit;
• (e) said liquid remaining in liquid phase at said temperature even if pressure in the tank is lost;
• and
• (f) means operatively associated with one of said diaphragm means for producing an electrical output signal proportional to the difference between the pressures at the respective locations of said two diaphragm means, said difference being a function of the level of liquid in the tank.