| 摘要 |
A fluid level detector (<B>1</B>) is mounted within a port (<B>2</B>) in a wall (<B>3</B>) of a vessel which contains a hazardous liquid, such as a petrochemical. The detector comprises a light transmitter (<B>6</B>) for transmitting light towards an optical element such as a prism (<B>7</B>), and a light receiver (<B>8</B>) for receiving light reflected back from the optical element. Electrical circuitry, mounted on a printed circuit board (<B>9</B>), detects signals from the light receiver and controls the transmission of light via the transmitter. The entire componentry is held in a potting compound (<B>11</B>), such as epoxy, to protect it from chemical and physical damage and to physically support it. A glass housing (<B>12</B>) surrounds the components of the detector, or alternatively the components are remotely located from the housing, the light being conducted to and from the element by optical fibres. Compressible material (<B>15</B>, <B>21</B> and <B>22</B>) lines the inner surface of the glass housing to absorb expansion and contraction differences between the glass and potting material due to temperature changes.
|
