Introduced the valve characteristic features! !

Safety valve is the boiler, pressure vessel and other pressure equipment safety attachments, can effectively prevent explosion accident caused by overpressure production device. Therefore, the relief valve is very important in the chemical plant. Here described in detail the classification, characteristics, selection and installation requirements. The classification and features of the relief valve 1. According to the different methods of medium to discharge, relief valve can be divided into totally enclosed and semi-enclosed and open three. (1) totally enclosed relief valve exhaust, all through the exhaust gas emission, medium can't between external leakage, mainly used for medium for toxic, flammable gas containers. (2) the semi-closed part of the relief valve discharge by gas through the exhaust pipe, there is also a part of from the bonnet and the clearance between the valve stem leakage, gases used for medium to not pollute the environment more containers. (3) open the bonnet is wide open, the relief valve spring chamber and atmosphere are interlinked, it is beneficial to lower the temperature of the spring, mainly is suitable for the medium for steam, and the atmosphere of high temperature gas containers that don't pollute. 2. According to the overall structure and the loading mechanism is different, the relief valve according to its overall structure and the different loading mechanism can be divided into heavy hammer lever, spring type and pulse type 3 kinds. Three types of safety valve, using more common is spring loaded safety valve. (1) a heavy hammer lever type safety valve, is the use of heavy hammer and leveraged to balance the force acting on the disc. According to the principle of leverage, it can use the heavy hammer through leverage with the increase of quality of the smaller force become larger, and by moving the position of the heavy hammer ( Or transform the quality of the heavy hammer) To adjust the relief valve opening pressure. Advantages: heavy hammer lever type relief valve has simple structure, adjustment, easy and accurate, and the load will not have larger by the rise of the disc, is suitable for high temperature occasion, used more widely, especially in the boiler temperature and high pressure vessel. Disadvantages: but is bulky, heavy hammer lever type safety valve structure vibration loading mechanism easily, and often the leakage due to vibration; The back pressure is low, is not easy to shut down and keep tight after opening. (2) spring loaded safety valve, is the use of compression spring force to balance the forces acting on the disc. Spiral cast the amount of compression spring can turn the adjusting nut to adjust it, using this structure can according to need correction of the relief valve opens, Setting) Pressure. Advantages: light spring safety valve structure is compact, has a high sensitivity, the installation position is not restricted, and because of the sensitivity of the vibration is small, so can be used for the transportable pressure vessel. Disadvantages: add the load will change as the valve opens and, namely with the increase of the disc, spring compression ratio increases, the force acting on disc starts to increase. This is unfavorable for relief valve rapid opening. In addition, the spring on the valve will be because of the effect of long-term exposure to high temperature and reduce tension. Used in the container of high temperature, often want to consider the heat insulation or heat dissipation problem of spring, so that the structure is complicated. (3) pulse valve consists of the main valve and auxiliary valve, through the role of the pulse and auxiliary valve to drive the main valve action, its structure is complex, generally only applies to large volumes of boiler and pressure vessel safety. 3. According to action principle according to principle of classification, can be divided into direct acting safety valve and the direct acting safety valve. (1) direct acting safety valve is opened under the direct effect of working medium, rely on the working medium pressure to overcome the effect of loading mechanism on the mechanical load of the disc, the valve opens. The relief valve has simple structure, quick, good reliability, etc. But because the structure load, the load size is restricted, cannot be used in high pressure, large caliber. (2) the direct acting safety valve, relief valve can be divided into such pilot operated relief valve, motivating the safety valve of auxiliary device. Pilot operated relief valve: it is depend on medium from a pilot valve to drive or control, and the pilot valve itself is a direct acting safety valve, sometimes also adopt other forms of the valve. Pilot operated relief valve is suitable for the occasion of high pressure and large diameter. Pilot operated relief valve of the main valve can also be designed to rely on the working medium to seal form, or you can on the disc is much bigger than direct acting safety valve of the mechanical load, thus has good sealing performance. At the same time, it rarely influenced by back pressure. The safety valve of the reliability of the drawback is that it related to the main valve and pilot valve, action as quickly as direct acting safety valve, reliable, and the structure is relatively complex. 4. In accordance with the valve disc to open the big height and diameter of the relief valve flow ratios, a safety valve and relief valve is mainly divided into micro and all safety valve two kinds. (1) micro rev micro safety valve and safety valve opening height less than a quarter, the diameter of the flow channel is usually 1/40 a 1/20 the diameter of the runner. Raise safety valve movement process is proportional action, it is mainly used for liquid occasions, sometimes also used in the gas situation of emissions is small. (2) full rev safety valve full rev safety valve opening height is greater than or equal to the runner diameter of a quarter. The rev safety valve discharge valve seat throat is the size of small cross-sectional area. Its action process is to belong to two acting, must use a lifting mechanism to achieve full open, full and safety valve is mainly used in the occasion of gas medium.