| 摘要 |
<p>A sensor for indicating the presence of liquid hydrocarbons on or in groundwater, comprising a column of spacers (12) supported on a vertical, hollow spindle (10), the spacers (12) being made of a material which dissolves in or is structurally weakened by the liquid hydrocarbon concerned, and a means of sensing the shortening of that column, should one or more of the spacers (12) be dissolved, or partially dissolved, whereby to detect the presence of such hydrocarbon(s) in or on the groundwater. The detection system includes a float (14) which is disposed on the spindle beneath the column of spacers (12) and carries a magnet. A magnetic switch disposed within the spindle (10) responds to the presence of the magnet at a location (A) corresponding to the column of spacers having shortened, as a result of the presence of liquid hydrocarbons. <IMAGE></p> |
