Introduction of mechanical seals

机械密封件属于精密、结构较为复杂的机械基础元件之一，是各种泵类、反应合成釜、透平压缩机、潜水电机等设备的关键部件。其密封性能和使用寿命取决于许多因素，如选型、机器的精度、正确的安装使用等。

Mechanical seals belong to one of the mechanical components with complex structure and precision. They are the key components of all kinds of pumps, reaction kettle, turbo compressor, submersible motor and so on. Its sealing performance and service life depend on many factors, such as selection, precision of the machine, correct installation and use, etc.

1、机械密封的基本概念

1. The basic concept of mechanical seal

机械密封是指由至少一对垂直于旋转轴线的端面在流体压力和补偿机构弹力（或磁力）的作用下以及辅助密封的配合下保持贴合并相对滑动而构成的防止流体泄漏的装置。补偿环的辅助密封为金属波纹管的称为波纹管机械密封。

Mechanical seal is composed of at least a pair of ends which are perpendicular to the axis of rotation, which are retained under the action of fluid pressure and compensatory mechanism elastic force (or magnetic force) and auxiliary seal to keep up with relative sliding and prevent fluid leakage. The auxiliary seal of the compensation ring is called the bellows mechanical seal, which is called the metal bellows.

2、机械密封的组成

2. The composition of mechanical seal

主要有以下四类部件。a.主要密封件：动环和静环。b.辅助密封件：密封圈。c.压紧件：弹簧、推环。d.传动件：弹箕座及键或固定螺钉。

There are four main types of components. A. main seals: moving rings and static rings. B. auxiliary seal: seal ring. C. compress: spring, push ring. D. drive parts: elastic skip and key or fixed screw.

应注意问题

Attention should be paid to problems

1、安装时注意事项

1. Precautions for installation

（1）要十分注意避免安装中所产生的安装偏差

(1) pay great attention to avoid installation deviation from installation

a、上紧压盖应在联轴器找正后进行，螺栓应均匀上支，防止压盖端面偏斜，用塞尺检查各点，其误差不大于0.05毫米。

A, tighten the gland should be aligned in the coupling bolts should be uniform, to prevent the end cap oblique, with feeler check, the error is less than 0.05 mm.

b、检查压盖与轴或轴套外径的配合间隙（即同心度），四周要均匀，用塞尺检查各点允差不大于0.01毫米。

The gap with B, check the gland and the shaft or shaft diameter (i.e. concentricity), around to evenly, not more than 0.01 mm check with the feeler the tolerance.

（2）弹簧压缩量要按规定进行，不允许有过大或过小现象，要求误差2.00毫米。过大会增加端面比压，另速端面磨损。过小会造成比压不足而不能起到密封作用。

(2) the quantity of spring compression should be carried out according to the regulations, and it is not allowed to have too big or too small phenomenon, and the error is 2 millimeters. Over the end of the assembly to increase the end surface pressure, and the other speed end wear. Too small can cause insufficient pressure and can not act as a seal.

（3）动环安装后髯保证能在轴上灵活移动，将动环压向弹簧后应能自动弹回来。

(3) ring after installation to ensure beard can move flexibly on the shaft, the moving ring pressure to the spring should be able to automatically bounce back.

2、拆卸时注意事项

2. Precautions for dismantling

（1）在拆卸机械密封时要仔细，严禁动用手锤和扁铲，以免损坏密封元件。可做一对钢丝勾子，在对自负盈亏方向伸入传动座缺口处，将密封装置拉出。如果结垢拆卸不下时，应清洗干净后再进行拆卸。

(1) carefully in the disassembly of mechanical seal, prohibited the use of hammer and chisel, so as not to damage the sealing element. A pair of wire hook can be made, and the sealing device is pulled out by extending the direction of the self profit and loss into the gap of the drive seat. If the scale is disassembled, it should be cleaned and then disassembled.

（2）如果在泵两端都用机械密封时，在装配，拆卸过程中互相照顾，防止顾此失彼。

(2) if both ends in the pump with mechanical seal, take care of each other in the assembly, the disassembly process, prevent the care for this and lose that.

（3）对运行过的机械密封，凡有压盖松动使密封发生移动的情况，则动静环零件必须更换，不应重新上紧继续使用。因为在之样楹动后，摩擦副原来运转轨迹会发生变动，接触面的密封性就很容易遭到破坏。

(3) for a mechanical seal that has been run, if there is a pressure relief and loosening, the movement of the seal will take place. Then the parts of the moving ring must be replaced, and it should not be tightened up and used again. Because in the kind of dynamic friction Ying, the original orbit will change, the contact surface of the seal is very vulnerable to damage.

机械密封件正常运行和维护

Normal operation and maintenance of mechanical seals

1、启动前的准备工作及注意事项

1. Preparatory work and precautions before starting

（1）全面检查机械密封，以及附属装置和管线安装是否齐全，是否符合技术要求。

(1) comprehensive inspection of mechanical seals, as well as the complete installation of accessories and pipelines, and whether it meets the technical requirements.

（2）机械密封启动前进行静压试验，检查机械密封是否有泄漏现象。若泄漏较多，应查清原因设法消除。如仍无效，则应拆卸检查并重新安装。一般静压试验压力用2~3公斤/平方厘米。

(2) the static pressure test is carried out before the mechanical seal is started to check the leakage of the mechanical seal. If the leakage is more, we should find out the reasons and try to eliminate it. If it is still ineffective, it should be dismantled and reinstalled. The pressure of the general static pressure test is 2~3 kg / sq cm.

（3）按泵旋向盘车，检查是否轻快均匀。如盘车吃力或不动时，则应检查装配尺寸是否错误，安装是否合理。

(3) according to the pump rotate to turning check whether a uniform. Such as turning demanding or not move, it should check whether the assembly size error installation is reasonable.

2、安装与停运

2, installation and outage

（1）启动前应保持密封腔内充满液体。对于输送凝固的介质时，应用蒸气将密封腔加热使介质熔化。启动前必须盘车，以防止突然启动而造成软环碎裂。

(1) the sealing cavity should be filled with liquid before starting. When the solidified medium is transported, the vapor is used to heat the sealing cavity to melt the medium. Before the start must be turning in order to prevent the sudden start caused by soft ring fragmentation.

（2）对于利用泵外封油系统的机械密封，应先启动封油系统。停车后最后停止封油系统。

(2) the sealing oil system should be started first for the mechanical seal using the pump sealing oil system. Stop sealing oil system after parking.

（3）热油泵停运后不能马上停止封油腔及端面密封的冷却水，应待端面密封处油温降到80度以下时，才可以停止冷却水，以免损坏密封零件。

(3) after the shutdown of the hot oil pump, the cooling water of the sealing oil cavity and the face seal can not be stopped immediately. When the oil temperature of the face seal is below 80 degrees, the cooling water can be stopped, so as not to damage the sealing parts.

3、运转

3. Operation

（1）泵启动后若有轻微泄漏现象，应观察一段时间。如连续运行4小时，泄漏量仍不减小，则应停泵检查。

(1) if there is a slight leakage after the pump is started, it should be observed for a period of time. If the leakage is still not reduced for 4 hours, the pump should be checked.

（2）泵的操作压力应平稳，压力波动不大于1公斤/平方厘米。

(2) the operating pressure of the pump should be stable, and the pressure fluctuation is not more than 1 kg / sq cm.

（3）泵在运转中，应避免发生抽空现象，以免造成密封面干摩擦及密封破坏。

(3) during the operation of the pump, the pumping should be avoided, so as to avoid the dry friction of the seal surface and the seal damage.

（4）密封情况要经常检查。运转中，当其泄漏超过标准时，重质油不大于5滴/分，轻质油不大于10/分，如2-3日内仍无好转趋势，则应停泵栓查密封装置。

(4) the sealing condition should be checked regularly. During operation, when the leakage exceeds the standard, the heavy oil is no more than 5 drops / min, and the light oil is no more than 10/ points. If there is no improvement trend within 2-3 days, the pump seal should be stopped to check the sealing device.

密封”在我国的发展源远流长，古人曾经用棉、麻等纤维来做提水机械的密封件，而国外到1782年才使用填料。密封的重要性，在这里就不多说了，如今国外 已经出现研究密封规律、密封装置设计技术和应用科学原理的学科——“密封学”，科研院校也有专门研究密封学的专业课程，而在我国，迄今为止，据我所知，大 学里有流体力学和液压传动等课程，但还没有一个专门研究密封的“密封系”，所以我们的研究水平与国外相比，还是有所差距的。

The development of the seal in our country has a long history. The ancient people used cotton, hemp and other fibers as the seals for the water extraction machinery, and the packing was used only in 1782. The importance of the seal, here is not to say, now have already appeared in academic research law, seal sealing technology design and application of the principle of scientific equipment - "seal", scientific research institutions also have professional courses devoted to the study of seal, but in our country, so far as I know, there are fluid mechanics and the hydraulic transmission course in the University, but also there is no special research on sealing seal system, compared with foreign research level so we still have the gap.

密封所设计的专业领域非常多，除了材料和机械方面，还有力学（包括流体力学、边界层理论等等）、摩擦学、自动控制等等。所以对密封来讲，研究难度也是相对较大的。国内密封行业的水平，个人认为与国外相比差距应该不少于50年。

There are many specialties in seal design. Besides material and mechanical aspects, there are mechanics (including fluid mechanics, boundary layer theory, etc.), tribology, automatic control and so on. Therefore, for the seal, the research difficulty is relatively large. The domestic seal industry level, the individual thinks that the gap should be less than 50 years compared with foreign countries.

关于密封原理

On the principle of sealing

想学习密封，就一定要先了解泄漏，泄漏的原理了解了，那相对应密封的机理也

If you want to learn to seal, you must first understand the leakage, the principle of leakage, and the mechanism that should be sealed relatively.