Boiler Accessories - Tawajod Industrial

Boiler accessories By structure According to its overall structure and different loading mechanism, it can be divided into three types: hammer lever type, spring type and pulse type. 1. Heavy Hammer Leverage Safety Valve Heavy hammer lever relief valve balances the force acting on the valve disc…

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Boiler accessories

By structure

According to its overall structure and different loading mechanism, it can be divided into three types: hammer lever type, spring type and pulse type.

1. Heavy Hammer Leverage Safety Valve

Heavy hammer lever relief valve balances the force acting on the valve disc by using a heavy hammer and lever. According to the principle of lever, it can use the weight with smaller weight to gain greater force through the increase of lever, and adjust the opening pressure of safety valve by moving the position of the weight (or changing the weight of the weight).

The weight hammer lever relief valve is simple in structure, easy to adjust and more accurate. The load added will not increase greatly because of the increase of the valve disc. It is suitable for higher temperature situations. It was used widely in the past, especially in boilers and pressure vessels with higher temperature. However, the structure of the lever relief valve with heavy hammer is bulky, and the loading mechanism is easy to vibrate, and often leaks due to vibration; its backing pressure is low, and it is not easy to close and keep tight after opening.

2. Spring slightly open safety valve

Spring micro-open safety valve uses the force of compression spring to balance the force acting on the valve disc. The compression of the coil spring can be adjusted by turning the adjusting nut on it. With this structure, the opening (setting) pressure of the safety valve can be adjusted according to the need. The spring slightly open safety valve has the advantages of compact structure, high sensitivity, unrestricted installation position, and low sensitivity to vibration, so it can be used in mobile pressure vessels. The disadvantage of this safety valve is that the load will change with the opening of the valve, that is, with the increase of the valve disc, the compression of the spring will increase, and the force acting on the valve disc will also increase. This is detrimental to the quick opening of the safety valve. In addition, the spring on the valve will be affected by high temperature for a long time and reduce the elastic force. When used in higher temperature containers, it is often necessary to consider the heat insulation or heat dissipation of springs, which makes the structure more complex.

3. Pulse relief valve

Pulse relief valve is composed of main valve and auxiliary valve. Pulse action of auxiliary valve drives the action of main valve. Its structure is complex. It is usually only suitable for boilers and pressure vessels with large safety discharge.

Among the above three types of safety valves, spring type safety valves are commonly used.

By medium

According to the different ways of medium discharge, safety valves can be divided into three types: fully closed, semi-closed and open.

1. Fully enclosed safety valve

When fully enclosed relief valve exhausts, all the gas is discharged through the exhaust pipe, so the medium can not leak out. It is mainly used for toxic medium. Containers for flammable gases.

2. Semi-closed safety valve

The gas discharged by the semi-closed safety valve is partly through the exhaust pipe, and partly leaks out from the gap between the valve cover and the valve stem. It is mostly used for containers where the medium is non-polluting gas.

3. Open safety valve

The valve cover of the open safety valve is open to connect the spring chamber with the atmosphere, which is conducive to reducing the temperature of the spring. It is mainly suitable for vessels with steam medium and high temperature gas which does not pollute the atmosphere.

Open by disc

According to the ratio of the maximum height of disc opening to the diameter of the flow passage of the safety valve, the safety valve can be divided into two types: spring micro-open closed high-pressure safety valve and spring full-open safety valve.

1. Closed high-pressure safety valve with spring slightly opened

The opening height of the micro-open safety valve is less than 1/4 of the diameter of the runner, usually 1/40-1/20 of the diameter of the runner. The action process of the micro-open safety valve is proportional, which is mainly used in liquid occasions and sometimes in gas occasions with small discharge.

2. Spring Fully Open Safety Valve

The opening height of the full-open safety valve is greater than or equal to 1/4 of the diameter of the runner. The discharge area of the full-open relief valve is the minimum cross-section area of the throat of the seat. Its action process belongs to two-stage action mode, which can only be fully opened by means of a lifting mechanism. Full-open safety valve is mainly used in the case of gas medium.

3. Open-in relief valve

The opening height is between micro-opening and full-opening. It can be made into two-stage action or proportional action.

According to the principle of action

According to the principle of action, it can be divided into direct-acting safety valve and non-direct-acting safety valve.

1. Direct acting safety valve

Direct acting relief valve is opened under the direct action of working medium, that is to say, relies on the action of working medium pressure to overcome the mechanical load imposed on the valve disc by the loading mechanism, so that the valve can be opened. The safety valve has the advantages of simple structure, quick action and good reliability. However, due to the structural loading, its load size is limited, and can not be used in high-pressure, large-caliber occasions.

2. Non-direct acting safety valve

This kind of safety valve can be divided into pilot safety valve and power assistant safety valve.

Pilot safety valve is driven or controlled by the medium discharged from the pilot valve. The pilot valve itself is a direct-acting safety valve, sometimes other forms of valves are also used. Pilot safety valve is suitable for high pressure and large caliber occasions. The main valve of pilot relief valve can also be designed to be sealed by working medium, or it can impose a much larger mechanical load on the disc than the direct acting relief valve, so it has good sealing performance. At the same time, its movements are seldom affected by back pressure. The disadvantage of this kind of safety valve is that its reliability is related to the main valve and guide valve. Its action is not as fast and reliable as that of direct acting safety valve, and its structure is more complex.

Safety valve with power assistant device relies on a power assistant device under normal opening pressure.