Impulse safety valve

Impulse safety valve

Pulse type safety valve is mainly used for power plant boilers, pressure vessels, temperature reduction and pressure relief device and other equipment, to prevent pressure exceeding the allowable pressure value, to ensure the safe operation of equipment. Is a kind of safety protection valve, its opening and closing parts under the action of external forces in the normally closed state, when the equipment or pipe medium pressure rise, exceed the specified value automatically open, through the discharge of the system to prevent the medium pressure in the pipeline or equipment beyond the specified value.

Performance parameters of pulse relief valve

1. Working pressure: 1.6mpa - 42.0mpa.

2. Working temperature: -20℃+550℃.

3. Driving mode: manual and automatic.

4. Connection: thread, flange and welding.

5. Manufacturing standards: GB, JB, HG, API, ANSI, BS, JIS, JPI, etc.

6. Body material: copper, cast steel, carbon steel, WCB, stainless steel, 304, 304L, 316, 316L, etc.

Safety valve working principle:

Safety valve is a kind of automatic relief protection device opened by inlet static pressure, it is one of the most important safety accessories of pressure vessel, its function is: when the pressure in the vessel exceeds a certain value, depending on the pressure of the medium itself automatically open the valve, quickly discharge a certain amount of medium. When the pressure in the container falls to the allowable value, the valve automatically closes, so that the pressure in the container is always lower than the upper limit of the allowable pressure, automatically prevent the possibility of accidents due to overpressure, so the safety valve is also known as the ultimate protection device of the pressure vessel.

Safety valve type classification:

Safety valve structure has two main categories: spring type and lever type. Spring type refers to the sealing force of the disc and seat by the spring. A lever is the force exerted by a lever and a heavy hammer. With the need for large capacity, there is a pulse safety valve, also known as the pilot safety valve, by the main safety valve and auxiliary valve composition. When the medium pressure in the pipeline exceeds the specified pressure value, the auxiliary valve is first opened. The medium enters the main safety valve along the pipe, and the main safety valve is opened to reduce the medium pressure of ***.

1. Lever safety valve

A heavy hammer lever relief valve USES a heavy hammer and lever to balance the force acting on the disc. According to the lever principle, it can use a heavy hammer with a small mass to obtain a large force by increasing the lever, and adjust the opening pressure of the relief valve by moving the weight of the heavy hammer (or changing the weight of the heavy hammer). Heavy hammer lever safety valve structure is simple, easy to adjust and more accurate, the added load will not increase due to the increase of the disc, suitable for higher temperature occasions, the past used more commonly, especially in the boiler and the pressure vessel with higher temperature. But the structure of the heavy hammer lever safety valve is heavy, the loading mechanism is easy to vibrate, and often causes leakage due to vibration. Its return seat pressure is low, after opening not easy to close and keep tight.

2. Spring safety valve

A spring-loaded safety valve USES the force of the compression spring to balance the force acting on the disc. The compression of the helical coil spring can be adjusted by turning the adjusting nut on it, with which the opening (setting) pressure of the relief valve can be corrected as needed. The spring micro - opening safety valve is light and compact in structure, high in sensitivity and unrestricted in mounting position. The disadvantage of this relief valve is that the load applied varies with the opening of the valve, that is, as the disc rises, the compression of the spring increases and the force on the disc increases. This is detrimental to the quick opening of the relief valve. In addition, the spring on the valve will be affected by high temperature for a long time and reduce the spring force. When used in containers with higher temperatures, the spring is often considered for thermal insulation or heat dissipation, thus complicating the structure.

3. Pulse relief valve

Pulse type safety valve is composed by main valve and auxiliary valve, through the auxiliary valve pulse action drives the main valve action, its structure is complex, usually only suitable for the boiler and pressure vessel with a large quantity of safe discharge. Of the three types of safety valves, the spring type is the most common.

Safety valve selection principles:

1, steam boiler safety valve, the general choice of open open spring safety valve.

2, liquid medium with safety valve, generally choose micro - opening spring safety valve.

3, air or other gas with the safety valve, the general choice of closed open spring safety valve.

4, oil well outlet safety valve, generally choose pilot safety valve.

5. The high-pressure bypass safety valve of steam power generation equipment shall be the pilot safety valve with dual functions of safety and control.

6. If it is required to open the safety valve regularly, the safety valve with lifting wrench should be selected. When the medium pressure reaches more than 75% of the opening pressure, a lift wrench can be used to slightly lift the disc from the seat to check the opening flexibility of the relief valve.

7, if the medium temperature is higher, in order to reduce the temperature of the spring chamber, generally when the closed safety valve operating temperature more than 300℃ and open safety valve operating temperature more than 350℃, should choose the safety valve with radiator.

8. If the back pressure at the outlet of the safety valve is variable and the change exceeds 10% of the opening pressure, the bellows safety valve shall be selected.

9. If the medium is corrosive, bellows safety valve should be selected to prevent the failure of important parts due to medium corrosion.

Safety valve installation and maintenance should pay attention to the following:

1. Safety valve shall be installed vertically.

2. There should be no resistance at the exit of the safety valve to avoid pressure.

3, safety valve before installation should be specially tested, and check the official seal.

4. Safety valve shall be inspected regularly during use.