The function of spring type safety valve is to prevent the medium pressure in the pipeline or device from exceeding the specified value, so as to achieve the purpose of safety protection.

Spring type safety valve is a kind of safety protection valve. Its opening and closing parts are normally closed under the action of external force. When the medium pressure in the equipment or pipeline increases and exceeds the specified value, it will open automatically. By discharging the medium outside the system, the medium pressure in the pipeline or equipment will be prevented from exceeding the specified value. Spring type safety valve belongs to automatic valve category, which is mainly used on boilers, pressure vessels and pipelines. The control pressure does not exceed the specified value, which plays an important role in protecting personal safety and equipment operation.

According to the opening height of spring safety valve flap, it can be divided into micro open spring safety valve and full open spring safety valve. The opening stroke height of micro open spring safety valve is ≤ 0.05d0 (minimum discharge throat diameter); the opening height of full open spring safety valve is ≤ 0.25d0 (minimum discharge throat diameter).

Spring type safety valve is divided into vertical hammer type, lever type, spring type and pilot type (pulse type) according to the structure of valve body, which can be divided into closed type and non closed type. Closed spring type safety valve means that the discharged medium does not leak out. It is discharged to the designated place along the outlet. It is generally used in toxic and corrosive medium. For spring type safety valve for air and steam, non closed spring type safety valve is often used. The selection of spring type safety valve should be determined according to the actual sealing pressure. For spring-loaded safety valve, in the range of one nominal pressure (PN), there are several kinds of springs with working pressure level. When ordering, besides the model, name, medium and temperature of spring-loaded safety valve, the sealing pressure of valve body shall also be indicated, otherwise, the goods shall be supplied according to the maximum sealing pressure.

The installation and maintenance of spring safety valve shall pay attention to the following matters:

1. All kinds of spring safety valves shall be installed vertically.

2. There shall be no resistance at the outlet of spring safety valve to avoid pressure.

3. The spring type safety valve shall be specially tested before installation and its official tightness shall be checked.

4. The spring type safety valve in use shall be inspected regularly.

Selection of spring safety valve

Purchasing method of spring safety valve and related knowledge of spring safety valve

The safe discharge capacity of pressure vessel refers to the amount of gas that must be discharged in unit time in order to ensure that the pressure of pressure vessel will not rise again in case of overpressure.

The discharge capacity of spring safety valve refers to the discharge capacity of spring safety valve in unit time under discharge pressure when it is fully open.

For the boiler, the total displacement of spring safety valve must be greater than the maximum continuous evaporation of the boiler, and after all spring safety valves on the drum and superheater are opened, the steam pressure in the drum shall not exceed 1.1 times of the design pressure. For pressure vessels, it is required that the discharge capacity of spring safety valve must be equal to the safe discharge capacity of pressure vessels. The selection of spring safety valve should be considered from the following aspects:

(1) What type of spring type safety valve is selected for its structure mainly depends on the process conditions of the equipment and the characteristics of the working medium. In general, most boilers and pressure vessels use spring-loaded safety valves. If the working medium of the container is toxic, flammable and explosive, the closed spring safety valve shall be selected. For boilers, high-pressure vessels and medium and low-pressure vessels with large safety discharge capacity and not too rich wall thickness, it is better to select full open spring safety valve.

(2) Pressure range spring safety valve is designed and manufactured according to the nominal pressure standard series. Each spring safety valve has a certain working pressure range. Proper spring type safety valve shall be selected according to the maximum allowable working pressure of boiler and pressure vessel.

(3) The discharge capacity of the spring-loaded safety valve selected for the discharge capacity must be greater than the safety discharge capacity of the equipment, so as to ensure that when the boiler or pressure vessel is overpressured, the spring-loaded safety valve can discharge part of the medium in time when it is opened, so as to avoid the continuous increase of the pressure in the device.