What is a safety valve

What is a safety valve

Safety valve is a kind of safety protection valve, also known as exhaust valve, a kind of automatic valve. Its opening and closing parts are normally closed under the action of external force. When the pressure in the equipment or pipeline exceeds the set pressure of the safety valve, the pressing force is adjusted by adjusting the length of the spring force in the valve. When the pressure in the pipeline is higher than When the set value is set, the spring is reversely compressed and the oil leaks out, thereby controlling the pressure in the pipeline not to exceed a certain limit value, ensuring that the pressure of the medium in the equipment and the pipeline is below the set pressure, and protecting the equipment and the pipeline in normal Work to prevent accidents and reduce losses. 

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Safety valve disc classification

According to the ratio of the maximum opening height of the safety valve disc to the valve seat diameter, it can be divided into:
  ⑴Slight opening type: The opening height of the valve flap is 1/20~1/10 of the valve seat diameter. Due to the small opening height, the structure and geometry of this valve are not as strict as the full-open type, and the design, manufacture, maintenance, and testing are relatively convenient, but the efficiency is low.

  ⑵Full-open type: the opening height of the valve disc is 1/4~1/3 of the valve seat diameter

Safety valve disc classification

The working principle of the safety valve

The safety valve directly relies on the force generated by the medium pressure to overcome the mechanical load acting on the disc to open the safety valve. The mechanical load acting on the disc is mainly from the heavy hammer or spring, which is almost a fixed mechanical load. . To ensure the sealing performance of the safety valve, there must be strict requirements on the flatness and surface roughness of the valve seat sealing surface and the valve disc sealing surface.

The working principle of the safety valve

Safety valves are classified by structure

⑴Fully enclosed type: When the medium is discharged, it does not leak to the outside, but all is discharged through the drain pipe.
⑵Semi-closed type: When discharging the medium, one part is discharged through the drain pipe, and the other part leaks out from the fitting place of the valve cover and the valve stem.
⑶ Open type: When discharging the medium, it is not led to the outside, and it is directly discharged by the valve disc.

Safety valves are classified by structure

Safety valve structure classification

There are two main categories: spring type and lever type. The spring type means that the seal between the valve clack and the valve seat relies on the force of the spring. The lever type relies on the force of the lever and the heavy hammer. With the need for large capacity, there is another impulse safety valve, also called a pilot safety valve, which consists of a main safety valve and an auxiliary valve. When the medium pressure in the pipeline exceeds the specified pressure value, the auxiliary valve opens first, the medium enters the main safety valve along the conduit, and the main safety valve is opened to reduce the increased medium pressure.

Safety valve structure classification
Frequently Asked Question

Do you have any question?

The safety/pressure relief valve is a standard diaphragm safety/pressure relief valve, which is mainly used in heating, air conditioning, thermal storage hot water systems, irrigation systems, control of cold and heat sources and system pressure. When the system pressure exceeds the set value of the safety valve, the safety valve automatically opens to release the system pressure to the atmosphere, and automatically closes when the pressure is lower than the safety value, so that the system with the safety valve can operate safely.

According to the structure of the safety valve can be divided into ⑴ Heavy hammer (lever) type safety valve, ⑵Spring type safety valve, ⑶ Pulse safety valve.

Breathing valve is often used on the top of the storage tank. It can be used to exhale or inhale from its name. It is generally composed of two valve chambers, one as the pressure side and the other as the vacuum side. When the pressure of the storage tank is too high, the valve on the pressure side will open, and the valve on the vacuum side will be closed at the same time, so that the gas in the storage tank is discharged; if the pressure of the storage tank is lower than the design pressure, the valve on the vacuum side of the breathing valve will open At the same time, the valve plate on the pressure side is closed and the atmosphere is sucked in. Its main function is to balance the pressure of the storage tank and avoid its collapse or expansion. Generally, a flame arrestor is also connected to the lower part of the breathing valve. The safety valve is often used at the end of the pipeline. Excessive pressure in the pipeline will release the pressure, and it is generally used in conjunction with rupture discs.

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