System and method for optically detecting low liquid level condition

A dial assembly for use with a liquid level gauge having a gauge head for connection to a tank, the dial assembly comprising:

• a base connectable to the gauge head;
• a lens connected to the base;
• a disk being rotatably connected to at least one of the base and lens for rotation with respect thereto;
• a reflective layer connected to one of the base and disk;
• and
• a blocking layer positioned over the reflective layer for blocking at least a portion of the reflective layer upon rotation of the disk;
• wherein radiant energy reflected by the reflective layer is indicative of a first liquid level condition within the tank and the absence of reflected radiant energy is reflective of a second liquid level condition within the tank different from the first liquid level condition.

A method of determining a low liquid level condition within a tank, the method comprising:

• providing a liquid level gauge with an indicator dial with a reflective member and a blocking member for blocking at least a portion of the reflective member, the members being mutually rotatable upon a change in liquid level condition to selectively cover and expose an area of the reflective member;
• determining a reflectivity of the dial dependent on the amount of exposed area of the reflective member;
• and
• generating a low level warning signal when at least one of the following conditions occurs:
• a) the reflectivity is below a predetermined level, and b) a malfunction occurs during the step of determining a reflectivity of the dial.