| 摘要 |
A purge device for a gas supply line 18 to a burner comprises a valve 4 arranged upstream of the burner and controlled manually counter to the action of a return spring 2. To close the valve 4 for sufficient time for purging, the head 3 of the valve 4 is combined with a hydraulically controlled automatic return member 1. To be able to adjust this period of time individually, the return member 1 is composed of a cylinder 5 filled with a liquid, and wherein slides a sealed piston 6, and of a communication tube 7 connected to the said cylinder which provides communication between two chambers 9 and 10 formed by the piston and wherein an adjustable restriction 11 may be provided. To prevent escape of gas during an extended manipulation of the purge valve 4, its control member 13 has an additional valve head 14 which closes the valve 4 while it is being actuated, and disengages it successively as soon as manipulation thereof ceases. <IMAGE>
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