| 摘要 |
For detecting a level of a liquid in a container, an element is mounted in a container so as to extend along an area corresponding to the location where liquid depth is to be detected. That element is formed of a material having a "memory" which is actuated when the material is subjected to a predetermined temperature, to cause the material to change its shape and therefore alter the effective length of the element. Heat is provided to the element, as by causing an electrical current to pass therethrough, in such an amount as to cause said element to be heated to said predetermined temperature when said element is enveloped by air or some other fluid of relatively low heat-dissipating characteristic, but the liquid of the level of which is to be sensed has a relatively high heat-dissipating characteristic such that the liquid-enveloped sections of the element will not be raised to said predetermined temperature. It is only when a given length of said element is exposed to air or other fluid, thus causing that length to exceed said predetermined temperature, that sufficient force is developed to actuate an appropriate work means such as a switch controlling an alarm system or the like.
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