System for controlling the level of the liquid contained in a LPG tank or the like

A system for detecting a level of liquid in an LPG tank (1), comprising:

• a stem (2) mounted for rotation in the tank, an angular position of the stem corresponding to a level of liquid in the tank, the stem having an upper end with a permanent magnet for creating a magnetic field which varies with rotation of the stem, variations of the magnetic field corresponding to angular positions of the stem;
• a flanged body (3) connected to the tank, the upper end of the stem with the magnet, extending into the flanged body;
• an electronic sensor (5) adjacent the flanged body (3) but outside the tank, the sensor being in the magnetic field and including a disk and four Hall-effect sensor elements equally circumferentially spaced around 360 degrees and around the magnetic field and mounted on the disk, each sensor element generating a current that is proportional to the variations in the magnetic field adjacent the sensor element so that the currents of all the sensor elements together create digital logic information corresponding to the angular position of the stem and thus to the level of liquid in the tank, each sensor element being a binary sensor element which is either on or off so that the digital logic information is binary information;
• a radio transmitter (6) connected to the sensor (5) for transmitting the digital logic information to a remote location, the transmitter extending vertically from the disk in the container;
• a container (4) over the sensor and the transmitter and outside the tank for protecting the sensor and the transmitter;
• and
• a battery in the container for powering the electronic sensor and the transmitter.