| 摘要 |
A device for detecting conditions in a jig washbox (10) e.g. in a coal preparation plant comprises a stand pipe (13) closed at its upper end and connected at its base to the interior of the washbox below the liquid level (S) therein, a first flexible diaphragm (16) occluding the base of the pipe, a second flexible diaphragm (18) occluding the pipe substantially at the same level as the liquid in the washbox, there being liquid in the zone 17 between the flexible diaphragms, a rigid diaphragm (20) above the diaphragm (18) with valve means permitting free passage of air upwardly in the pipe, a bleed valve (22) permitting a controlled bleed of air in the reverse direction, and a transducer (23) adapted to detect the air pressure in the pipe above the diaphragm (20). The diaphragm (16) prevents air entering the pipe (17) and producing inconsistent results. <IMAGE> |
