The principle structure and role of safety valve

Time：2022/6/5 10:59:24 Category：TECHNICAL ARTICLE Source： Click：

Safety valve, also known as pressure relief valve, is automatically opened and closed according to the working pressure of the pressure system, generally installed in the closed system equipment.

Safety valve equipment or pipeline to protect the system safety. When the pressure in the equipment or pipeline exceeds the set pressure of the safety valve, it automatically opens and closes to ensure that the medium pressure in the equipment and pipeline is under the set pressure, protecting the equipment and pipeline from normal operation, preventing accidents and reducing losses.

Safety valve principle of action is based on force balance, once the pressure on the valve flap is greater than the spring set pressure, the valve flap will be pushed open by this pressure, the gas (liquid) in its pressure vessel will be discharged to reduce the pressure in the pressure vessel.

The safety valve plays a safety protection role in the system. When the system pressure exceeds the specified value, the safety valve opens and discharges a portion of the gas/fluid in the system into the atmosphere/pipe outside so that the system pressure does not exceed the allowable value, thus ensuring that the system is not subject to accidents due to high pressure.

There are two main types of safety valve structures: spring-loaded and lever-operated. Spring type refers to the valve flap and the valve seat seal by the force of the spring. Lever type is by the force of the lever and the weight. With the need of large capacity, there is another kind of pulse type safety valve, also called pilot type safety valve, which consists of main safety valve and auxiliary valve. When the medium pressure in the pipeline exceeds the specified pressure value, the auxiliary valve opens first, and the medium enters the main safety valve along the conduit and opens the main safety valve to reduce the increased medium pressure.

The discharge of the safety valve is determined by the caliber of the valve seat and the opening height of the valve flap, which can also be divided into two types: the opening height of the micro-opening type is (1/15) to (1/20) of the inner diameter of the valve seat, and the full-opening type is (1/3) to (1/4).

In addition, with the different requirements of use, there are closed type and unclosed type. Closed type means that the discharged medium does not leak out, all along the specified outlet, and is generally used for toxic and corrosive media. Non-closed type is generally used for non-toxic or non-corrosive media.