Spring type Safety Valve
Introduction:
Spring type safety valve means that the valve, plunger and other sealing elements of the valve are locked by the elastic pressure of the spring. Once the pressure of the pressure vessel is abnormal, the high pressure generated will overcome the spring pressure of the safety valve, so the locking device is jacked open to form a pressure relief channel to release the high pressure. According to the different opening height of valve disc, it can be divided into full lift type and micro lift type. The full lift type has large discharge capacity and good resilience, which is suitable for liquid and gas media, while the micro lift type is only suitable for liquid media.
Working principle:
According to the analysis of the opening action characteristics of the spring type safety valve, it can be concluded that: under the action of the external force FW, the change law of the external force FW in the whole process of a safety valve from closing to opening, and then from opening to closing, when the additional force increases from zero, the internal pressure PL × When the sum of S is just the spring preload, the valve opens slightly, increasing the media action area S, making the internal pressure force used to overcome the spring preload increase sharply, and the result is that the external force is reduced instantly. The first characteristic peak A appears. When the external additional force decreases gradually and reaches the closing point, due to the sudden decrease of the area of the medium, in order to maintain the balance of the force, the external additional force will rebound instantaneously, that is, the second characteristic peak point B. The above two characteristic peaks A and B are the technical basis for detecting the opening pressure and reseating pressure of the safety valve under online conditions.
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