Typical safety valve structure

1. Structural features of spring loaded safety valve

1).弹簧直接载荷微启式安全阀

1). Spring direct load micro lift safety valve

微启式安全阀是随着系统内的压力升高而逐渐开启的，没有辅助阀瓣增加开启高度的 专门机构

The micro opening safety valve is opened gradually with the increase of pressure in the system, and there is no special mechanism for auxiliary valve flap to increase the opening height

2). 弹簧直接载荷全启式安全阀

2) spring loaded full open safety valve

全启式安全阀，具有辅助增加阀瓣开启高度的专门机构。利用了作用在反冲盘式阀瓣扩大了的面积上的静压力以及流束的反作用力。

Full open safety valve, with a special mechanism to increase the opening height of the disc. The static pressure acting on the expanded area of the disc disc and the reaction force of the flow beam are used.

先导外置阀，是指先导阀设置在主阀的外部，通过管线与主阀的活塞腔及系

The pilot external valve means that the pilot valve is set outside the main valve, through the pipeline and the piston cavity and system of the main valve

统连通。这种结构通常用于开敞式安全阀，结构相对来说简单一些，调试比较方便．由

Unified connectivity. This structure is usually used for open safety valve, which is relatively simple and convenient for debugging

于结构不紧凑，连接点过多，无法用于易燃、易爆、有毒气体的场合。

It can not be used in inflammable, explosive and toxic gas occasions because of its uncompacted structure and too many connection points.

先导内置阀，先导阀设置在主阀腔内。为封闭式结构，可用于易燃、易爆、有毒气体的场合。由于先导阀设置在主阀腔内，调试比较困难一些。

Pilot built-in valve, the pilot valve is set in the main valve chamber. It is a closed structure, which can be used in flammable, explosive and toxic gas occasions. Because the pilot valve is set in the main valve chamber, it is difficult to debug.

3．内装式安全阀结构特点

3. Structural features of internal safety valve

是一种内装式安全阀，通过法兰直接与被保护装置相连。内装式安全阀为减少在被保护装置外侧的伸出高度、将阀瓣和阀座等零部件都设置在安装法兰的下部，介质排放出口直接向上。这种安全阀主要是用于液化石油气等介质罐车上。

The utility model relates to a built-in safety valve, which is directly connected with a protected device through a flange. In order to reduce the extension height outside the protected device, the internal safety valve sets the valve disc, valve seat and other parts at the lower part of the installation flange, and the medium discharge outlet directly upward. This kind of safety valve is mainly used in LPG and other medium tank cars.

4．带冷却机构的安全阀结构特点

4. Structural features of safety valve with cooling mechanism

这种结构的安全阀主要是用于高温高压的场合，冷却机构的设置是为了不把系统内的高温传递到安全阀的弹簧上，以免弹簧在高温下松弛，导致安全间不能保证密封或提前起跳。目前用于电厂的高压锅炉、石油化工厂的裂解炉上的安全阀，大部分是这种结构的。有的安全阀不仅带冷却机构，还带有一个减小安全阀回座冲击的阻尼装置，能有效地保护阀座密封面。

The safety valve of this structure is mainly used in high-temperature and high-pressure situations. The cooling mechanism is set so as not to transfer the high temperature in the system to the spring of the safety valve, so as to prevent the spring from relaxing under high temperature, so that the safety room cannot be sealed or take off in advance. At present, most of the safety valves used in high-pressure boilers of power plants and cracking furnaces of petrochemical plants are of this structure. Some safety valves not only have cooling mechanism, but also a damping device to reduce the impact of safety valve reseating, which can effectively protect the sealing surface of valve seat.

5．背压平衡式安全阀结构特点

5. Structural features of back pressure balanced safety valve

背压平衡式安全阀是把背压对安全阀的动作特性〔 开启压力、关闭压力、开启高度、排量）影响降低到最小的限度。这类安全阀主要有两种型式：活塞式和波纹管式。

Back pressure balanced safety valve is to minimize the influence of back pressure on the action characteristics of safety valve (opening pressure, closing pressure, opening height, displacement). There are two types of safety valve: piston type and bellows type.

1).活塞式安全阀

1). Piston safety valve

活塞式安全阀也有多种型式。它是在导向套的侧面开了一个通气孔．使得活塞内的压力和排放侧的压力相同，从而使得作用在阀瓣上、下两面的背压力相互抵消。活塞的顶面面积，由于阀盖通大气，所以该活塞顶面承受的压力就是大气压。

There are many types of piston safety valve. A vent is opened on the side of the guide sleeve, so that the pressure in the piston is the same as that in the discharge side, so that the back pressure acting on the upper and lower sides of the valve disc is mutually offset. The top surface area of the piston. Because the valve cover is open to the atmosphere, the pressure on the top surface of the piston is atmospheric pressure.

2).波纹管平衡式安全阀

2). Bellows balanced safety valve

在波纹管平衡式安全阀中，阀瓣上设置一个波纹管．波纹管上端与间体连接在一起，下端与阀瓣相连，波纹管罩住了阀瓣的导向部分及阀瓣的顶部，一个作用是把介质与阀盖隔离起来，另外一个作用就是保证阀瓣上、下面的受背压面积相等．即波纹管的有效面积 Ab，与安全阀阀瓣（阀座）密封面的面积相等．

In the bellows balanced safety valve, a bellows is arranged on the valve disc. The upper end of the bellows is connected with the interstellar body, and the lower end is connected with the valve disc. The bellows covers the guiding part of the valve disc and the top of the valve disc. One function is to isolate the medium from the valve bonnet, and the other is to ensure that the back pressure area on and below the valve disc is equal, that is, the effective area of the bellows ab , and the area of the sealing surface of the safety valve disc (seat) is equal

这两种平衡式安全阀的排放管中都有着较高的压力，为了防止波纹管破裂或泄漏。在其阀盖上都开设了一个足够大的排气孔，以保证在设计流量工况。不会产生明显的反压力。 如果直接排向大气有一定的危险性，则应当用管子将阀盖开孔接引到一个与阀门排放系统无关的安全场所。一旦波纹或活塞泄漏．这种安全阀将起不到平衡背压的作用。

There is a high pressure in the discharge pipe of these two balanced safety valves to prevent the bellows from breaking or leaking. A large enough vent hole is arranged on the valve cover to ensure the design flow condition. There will be no significant back pressure If it is dangerous to discharge directly to the atmosphere, the valve cover opening shall be connected to a safe place unrelated to the valve discharge system with pipes. In case of ripple or piston leakage, the safety valve will not balance the back pressure.