Why are the opening pressure and closing pressure of a safety valve different?
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This post was last edited by kareale88 on 2018-12-1 10:54. May I ask: 1. Why is the opening pressure of a safety valve different from its closing pressure? Isn’t it all spring compression force? 2. When the rated steam pressure is less than 1.27 MPa, the opening pressures are respectively the working pressure plus 0.02 MPa and the working pressure plus 0.04 MPa. When the rated steam pressure is greater than 3.82 MPa, the opening pressures are 1.05 times the working pressure and 1.08 times the working pressure, respectively. Why are there two opening pressures? ?
The spring is compressed when it is activated, and it rebounds when it returns to its original position. Where did the database mentioned by the original poster come from?
The second question: Generally, steam drums are equipped with two types of safety valves – one is called a control safety valve, and the other is called a service safety valve. The control safety valve operates at a lower pressure level and opens first
1. Before activation, the spring is stiff; when it returns to its original position, it becomes softer and the pressure is not as high. 2. Two safety valves are required to be installed on the boiler; one safety valve opens first, and the other opens later!
Both of these pressures are the corresponding initial pressures, rather than final pressures
The initial seating pressure is also set by the spring, right? Isn’t it the same as the launching pressure?
Isn’t the compressive force the same before the spring undergoes plastic deformation?
After the spring is compressed, its elasticity should change slightly, and temperature has a greater impact on the spring’s elasticity.