| 摘要 |
Double strand filters for fuel oil burners, which in the hitherto known embodiment could only be shut off by hand in the outlet duct, while the return duct was automatically shut off by a non-return valve, are provided with a double shut-off device to be actuated manually, such that the valve seals of two adjacent valve trains (4 and 16) arranged on a filter plate (1) are connected together through their guide rods (14 and 29) by an actuating bridge (12). The function of the automatically operating non-return valve is maintained by the non-return valve cone (9) being mounted separately and freely movable in the guide rod. The additional function of a safety valve is achieved, in the closed state and when the nominal pressure is exceeded, by the spring-loaded guide rod, at whose ends the valve seals are arranged, so that the excess pressure which exists for a short time, possibly due to the running-on of the fuel oil pump, is conducted away into the return flow duct, and an excess pressure arising in the flow duct because of the thermal expansion of the fuel oil is taken up in a volume reservoir which results from raising the guide rod (14) into the spring space (15). <IMAGE>
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