| 摘要 |
The safety device contains, in known manner, a pressure relief valve, a gas inlet valve, a gas backflow valve and a flame arrestor. The pressure relief valve piston is not only acted upon from the direction of the gas inlet passage but, at the same time, also on the other side by the operating pressure. The relative pressure equilibrium thereby achieved allows precise definition of the valve spring system irrespective of fluctuations in the operating pressure. The gas inlet valve is closed by means of a cylindrical spool; the operating pressure therefore acts radially on the closed valve, i.e. exerts no pressure in the direction of movement of the spool. After an explosion or some other gas backflow, the pressure of the valve spring is thus sufficient to initiate valve opening and, together with the fresh gas which subsequently flows into the spool, to completely open the valve. The pressure relief valve acted upon from both sides and the gas inlet valve equipped with a cylindrical spool make it possible for the first time to effect fully automatic cancellation of a pressure-controlled self-closure. The thermal self-closure takes place by means of a separately replaceable fusible element; the problems associated with the gas-tight sealing of such a screw-off element are solved by the use of the fusible element as the sealing body.
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