| 摘要 |
1509602 Electrical oil detectors JAPAN GASOLINE CO Ltd 20 June 1975 [25 June 1974] 26255/75 Heading G1N An oil detecting device for detecting the presence of oil on the surface of water or leakage from a pipe-line includes an electrically conductive particle layer which changes its resistance on coming into contact with oil. A conductive particle layer 4 of metals, metal oxides, carbon (graphite) is positioned in opening 1a of a rectangular plastics housing 1 and the opening is then sealed by a filter 2 of a water repellant oil passing material (e.g. polyfluoroethylene, silicon resin, synthetic resin filaments or natural fibre coated with resin. The layer 4 may be coated on the inner surface of filter 2 or the insulating plate 5. The filter 2 may contain a toxic to algae and shells to prevent them forming on the device. The filter may be in sheet form Fig. 3 (not shown). In operation the device is disposed in the medium to be monitored and its resistance measured via electrodes 3a, 3b which may be connected in one arm of a bridge circuit. Fig. 4 (not shown), the presence of oil causing the resistance between the electrodes to increase and thereby unbalance the bridge so as to trigger an SCR and energize an alarm circuit. Alternatively the detecting device may be connected as a feedback resistor between the output and inverting input terminals of a differential amplifier, Fig. 5 (not shown). The input resistances are adjusted so that in the absence of oil there is no output from the amplifier whereas when the resistance of the device increases in the presence of oil the amplification factor of the amplifier is increased and there is an output from the amplifier which fires the SCR. |
