This domestic device has been encapsulated over a dozen times, yet it still leaks; I’m really impressed!
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This post was last edited by microcosm de Smile on 2018-7-29 at 08:08. It was an original Japanese mechanical seal (a single-face, small-spring, non-integrated type). It started leaking after 6 years of use. Since there were no original spare parts available, the seal was removed and sent to a domestic seal manufacturer for replication. This is not meant to belittle anyone; the quality of domestically produced items has never been very good. I’ve dealt with many such parts in the past, and hardly ever have they met full satisfaction – they always had to be modified repeatedly just to function. I wasn’t holding out much hope this time either. There! Regarding the machine seal parts below. http://p3.pstatp.com/large/pgc-image/1532761267674923f9b06d1 Sealing component – it’s obvious at a glance that this is a simple single-face sealing element. I drew a simple structure diagram; it’s not a very good sketch, but it’ll have to do. Sketch of the mechanical seal: The five most essential sealing points of a mechanical seal are shown in the diagram. Point 3 represents the sealing between the stationary and rotating rings, while points 1, 2, 4, and 5 represent the static seals. As long as these five sealing points remain leak-free, the mechanical seal will function properly during operation. For ordinary mechanical seals, the most important components are of course the stationary and rotating rings; this is a critical aspect. The material used for these rings, as well as the precision of their manufacturing and the smoothness of their surfaces, are all very important factors. However, this type of mechanical seal is different from ordinary ones: the sealing point 4 between the shaft sleeve and the shaft is a conical surface seal, and the sealing is achieved by using the conical surface of the shaft sleeve to press against the gasket on the shaft shoulder. What a ridiculous design – conical surface seals require very precise specifications; even slight differences in angle, thickness, or width can lead to leakage. As shown in the following links: http://p3.pstatp.com/large/pgc-image/1532762006269713ab45fd1 and http://p1.pstatp.com/large/pgc-image/153276225258562cb4c4d73. As expected, after nearly two weeks of waiting, the newly ordered machine seal arrived late. I got to work right away, installed it, but water still seeped along the shaft. I removed it for inspection, replaced it with the cone-shaped gasket recommended by the manufacturer, and tried installing it again – yet there was still leakage. I went through this process of removing and reinstalling it about ten times, but I ran out of ideas. Since the amount of leakage is small, the possibility of leakage at the end faces of the rotating and stationary rings can be ruled out. The leakage occurs only along the axis, so seal points 1 and 5 can also be excluded; these seal points have been checked and seem to be leak-free as well. The most likely locations of leakage are points 2 and 4, namely the conical surface seal points. As analyzed earlier, there is a high possibility of leakage there. Additionally, for seal point 2, the domestic manufacturer changed the design of the seal element used there; normally, the sealing between the rotating ring of a mechanical seal and the shaft sleeve is achieved using a PTFE expansion ring, but the manufacturer replaced this with an O-ring, and the inner diameter of this O-ring is relatively large, which may also lead to leakage. http://p3.pstatp.com/large/pgc-image/1532763063062651d78568a There’s definitely no problem with our installation; it must be a defect in the design or manufacturing of the mechanical seal. We can only wait for the manufacturer’s technical staff to make improvements – it’s frustrating! They can’t even do it properly using the original spare parts – I’m really impressed. Their technical skills are poor, and they keep making random modifications. Just do it as it is; they keep altering things randomly every time. Is this what craftsmanship is supposed to look like? Were they inspected and tested before leaving the factory? No wonder domestic car engines aren’t of good quality – if they can’t even manufacture such small components properly, how can they expect to make decent engines?
I think a type 104 mechanical seal should be able to solve this problem.
It’s not precise; one can turn to professional manufacturers
The sealing O-ring between the static ring and the static ring gland is also a sealing point; have you installed it? If you can’t even install such a simple seal, I’m shocked. If the inner diameter of the O-ring is too large, you can wrap PTFE tape around it
For this O-ring, do you often wrap it with PTFE tape? Because you used PTFE tape, the supplier paid even less attention to the size of the O-ring; after all, a slight difference in size doesn’t cause any leakage
Sealed products are subject to a gas-tightness test before leaving the factory; it’s not enough to just check the sealing strip
I’m speechless at you! This child is unteachable!
This post was last edited by Little Universe de Smile on 2018-7-29 08:06. That O-ring has been installed; it wasn’t shown in the sketch
This post was last edited by Mechanical seal_CFVR on 2018-7-30 09:15. Seek a professional manufacturer to produce it. Don’t keep no spare parts at all just to save costs; when something breaks, don’t rush to find any manufacturer to measure, design, and supply a replacement – they might deliver it within two weeks, and it’s possible they will use some other existing seal as a substitute. Installation is also quite important!
I’ve encountered this before as well; the end face of the shaft sleeve is flat. When a PTFE gasket was damaged and caused leakage, switching to a conical surface along with using an appropriate O-ring resolved the issue. Things that are too intricate require high standards; it’s better to go for something simple and practical.