| 摘要 |
<p>A monitoring apparatus is described which is especially useful for level sensing. The apparatus includes a housing formed of light transmitting material and a monitoring lens on the housing. A directional light source is mounted within the housing to direct the light emitted therefrom towards the monitoring lens. A monitorable light sensitive device is also mounted in the housing, the device being disposed remote from the light path between the light source and the lens. The monitoring apparatus of the invention is reliable and efficient in operation and overcomes the disadvantages of presently available apparatus which usually are mechanically actuated conducting devices or float-level devices read by observation. These devices of the prior art are extremely limited depending upon the medium to be monitored. For example, it is difficult to monitor acids and alkalies or electrically conducted liquids by presently available apparatus.</p> |
