Brief introduction of spring slightly open safety valve
When the valve is not opened, the external additional force overcomes the static rigid force of the valve core. When the opening point is reached, the external additional force is changed to overcome the elastic force of the spring. The slope of the two changes with time is different, so the first inflection point C appears. Similarly, another inflection point D occurs when the valve is closed. These two inflection points correspond to the opening and reseating of the valve respectively, which are the technical basis for testing the opening and reseating pressure of the valve in cold state. It is not difficult to see from the above analysis that the key to the safety valve online testing technology is how to correctly and quickly find the corresponding opening characteristic points.
The spring slightly open safety valve uses the force of the compression spring to balance the force acting on the valve disc. The compression amount of the helical coil spring can be adjusted by turning the adjusting nut on it. Using this structure, the opening (setting) pressure of the safety valve can be corrected as required. The spring micro-opening safety valve has a light and compact structure, high sensitivity, unlimited installation position, and can be used on mobile pressure vessels because of its low sensitivity to vibration. The disadvantage of this safety valve is that the applied load will change with the opening of the valve, that is, as the valve disc rises, the compression of the spring increases, and the force acting on the valve disc also increases. This is detrimental to the rapid opening of the safety valve. In addition, the spring on the valve will reduce the elastic force due to the influence of high temperature for a long time. When it is used on a container with a higher temperature, the heat insulation or heat dissipation of the spring is often considered, which complicates the structure.