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Proper use, selection and constant pressure of safety valve

CHINA·HERO VALVE
2020-07-01

The safety valve is one of the important safety accessories of the boiler pressure vessel and all pressure equipment. It is an automatic valve. When the pressure equipment exceeds the allowable working pressure, the safety valve automatically opens to discharge excess media. When the pressure drops to the allowable working pressure, the safety valve closes automatically and the equipment operates normally. This shows that the safety valve plays a very important role in the safe operation of the pressure equipment.


1. Selection of safety valve


1. Small-scale steam-water boilers shall not use spring-type safety valves


According to the "Small and Atmospheric Hot Water Boiler Safety Supervision Regulations", water-sealed safety devices should be used, and the diameter of the water-sealed pipe should not be less than 25mm, the effective water column height should not exceed 4m, and only negative deviations are allowed. Type safety valve.


2. Steam boilers should use spring full-open safety valves


As we all know, the opening height of the micro-lift safety valve is proportional to the size of the pressure, and the opening action is slow. Its opening height is only six to one tenth of the full-lift safety valve. If the pressure suddenly increases The steam cannot be released quickly, so the pressure cannot be reduced quickly, which is very dangerous.


3. Pressure vessels containing poisonous, flammable or expensive media should use closed safety valves


When the safety valve leaks or acts during operation, because the safety valve is not closed on the outside, there is a slight gap between the internal parts. In addition to the discharge of the medium through the discharge pipe, a small amount of medium will leak through the small gap between the parts. Not only caused waste but also accidents.


Second, the working pressure of the safety valve does not match the working conditions of the equipment


Various specifications and performances of safety valves are associated with a certain working range, and have related sensitivity and reliability.


Each safety valve is equipped with a certain working pressure level, which means that it can work normally within a certain working range. If the fixed pressure is not within the range of the pressure level, the safety valve will not be adjusted to the specified cracking pressure, even if it is adjusted to the specified cracking pressure, the safety valve will not work properly.


3. Problems with installation


1. The outlet of the discharge pipe of the safety valve is higher than the discharge port of the safety valve so that water accumulates in the discharge pipe, resulting in corrosion of the safety valve and leakage.


2. The discharge pipe of the safety valve is not connected to a safe place. The discharge pipe of the safety valve is facing the road and pedestrians. Once the safety valve is relieved of pressure, it will burn the pedestrians and cause accidents.


3. The unnecessary support of the discharge pipe causes its load to be unreasonably added to the valve body of the safety valve, so that the concentricity of the safety valve is destroyed, and the preload of the spring cannot act evenly on the sealing surface, which also causes The leakage of the safety valve.


4. The setting pressure of the safety valve is improperly determined


According to the regulations, the set pressure of the steam boiler should be determined according to the regulations, and the pressure vessel should be determined according to the regulations of the pressure vessel. Many users have not determined the set pressure according to the regulations. . The author believes that unless the pressure is reduced due to insufficient strength, the set pressure of the boiler safety valve should be based on each rated working pressure, and the pressure vessel should be based on the design pressure, not the production process or The use force required by the pipe network system is the basis for adjustment.


——CHINA·HERO VALVE



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