| 摘要 |
<p>A drain blockage sensor comprising a housing (1) divided into two chambers (2 and 3) by a flexible diaphragm (4). Chamber (2) contains a sensing device that responds to the displacement of diaphragm (4) caused by pressure changes in chamber (3). The pressure changes are caused produced by the build up of effluent levels caused by downstream blockages in the drain. The sensing device produces a signal when the pressure difference across the diaphragm exceeds a predetermined value. Diaphragm (4) has a valve therein to compensate for changes in atmospheric pressure and ambient temperature. Alternatively, chamber (2) may include a vent to atmosphere.</p> |
