An improved liquid level sensor

摘要

Liquid level sensor (30) for detecting the presence or absence of liquid including a first light emitter (32), a prism (33) and a light detector (34). Reception of light at the light detector (34) is indicative of whether or not the prism (33) is surrounded by liquid. The level sensor (30) emits light in the visible spectrum that can be viewed by a person to verify that the level sensor (30) is operating.