Yong Heng upper seal failure

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J

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Feb 1, 2019
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CA, United States
My Yong Heng is a few months old and today blew the connection seal on the tube coming off the top of the high pressure cylinder. The pump reached 4200 PSI and stopped pressurizing after I did a purge. I could feel air rushing out of the fitting. The fitting seal is pretty interesting. It's a washer with an o-ring in the middle. The o-ring was pretty much eroded so I replaced with a new one from the spares kit that came with the pump. I'll try it out tomorrow. Has anyone else had this problem?

I noticed while the pump is running, mist jets would blow out on similar seals on the pump. If I need to buy more of these seals, does anyone know of a source? 
 
My Yong Heng is a few months old and today blew the connection seal on the tube coming off the top of the high pressure cylinder. The pump reached 4200 PSI and stopped pressurizing after I did a purge. I could feel air rushing out of the fitting. The fitting seal is pretty interesting. It's a washer with an o-ring in the middle. The o-ring was pretty much eroded so I replaced with a new one from the spares kit that came with the pump. I'll try it out tomorrow. Has anyone else had this problem?

I noticed while the pump is running, mist jets would blow out on similar seals on the pump. If I need to buy more of these seals, does anyone know of a source?
Click to expand...

These sealing washers are widely available on Aliexpress or platforms selling Chinese products. I have never had any of these washers failing on my Yong Heng. A recent leakage occurring at the joint between the outlet hose and the small black filter was due to the surface the washer sits on rusted, the washer itself is still OK. When installing these washers, it's better to apply some silicone grease to the rubber part first so it can be seated more easily when pressure is applied. 
 
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...might have been 20.00 worth + shipping from china.
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The sealing kit is being sold in China for 15 Chinese Yuan or about US$2 : 

https://item.taobao.com/item.htm?spm=2013.1.0.0.253634e2qJCt1s&id=591576524044&scm=1007.12144.95220.42296_0_0&pvid=f4da5ddf-e707-4c60-bc3c-7b3de2254d47&utparam=%7B%22x_hestia_source%22%3A%2242296%22%2C%22x_object_type%22%3A%22item%22%2C%22x_mt%22%3A0%2C%22x_src%22%3A%2242296%22%2C%22x_pos%22%3A3%2C%22x_pvid%22%3A%22f4da5ddf-e707-4c60-bc3c-7b3de2254d47%22%2C%22x_object_id%22%3A591576524044%7D

Shipping to Hong Kong adds US$1.3, shipping from Hong Kong to US with partial tracking is about US$5 so the total cost is about US$9.

If resold at US$60, the profit margin of the middle man is more than 500% !
 
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The seals that you require are known as Dowty bonded washers or seals. If you google that name, you should be able to find a supplier close to where ever you live. Here is where I got some cheaply for my 1/8-10mm Foster QD fittings. The size that fits the one that failed on your pump is 12mm. There should be two in your spare parts bag. It is unlikely that it will fail again unless you disassemble it regularly. https://www.aliexpress.com/item/PCP-Airfore-Airsoft-Pneumatics-Air-Seal-M10-High-Pressure-Gasket-Washer-O-Ring-Sealing-for-Mini/32857335858.html?spm=a2g0s.9042311.0.0.43694c4dTO6VbM
 
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The seals that you require are known as Dowty bonded washers or seals. If you google that name, you should be able to find a supplier close to where ever you live. Here is where I got some cheaply for my 1/8-10mm Foster QD fittings. The size that fits the one that failed on your pump is 12mm. There should be two in your spare parts bag. It is unlikely that it will fail again unless you disassemble it regularly. https://www.aliexpress.com/item/PCP-Airfore-Airsoft-Pneumatics-Air-Seal-M10-High-Pressure-Gasket-Washer-O-Ring-Sealing-for-Mini/32857335858.html?spm=a2g0s.9042311.0.0.43694c4dTO6VbM
Click to expand...


Thanks for the link. I'm assuming the one I need for future spares is M12. Relatively cheap when you don't need to buy extra parts you don't need. I used the AliExpress search tool with "High Pressure Gasket Washer" to locate different sizes.
 
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I installed the new seal from my spares kit that came with the pump last night. This morning it was fired up and it ran flawlessly. I had been seeing mysterious mist jets coming from various directions near the top of the pump but could not identify the source. This seal had apparently been failing from the beginning. Airgunfans said it was a good idea to use silicone grease on seals. I installed the seal before reading this but it is a real good idea. My double Tuxing filter setup was torn down for inspection and noted two of the end cap o-rings were pretty mangled. New o-rings and the remaining good ones were installed with silicone grease.

This pump is like working on an old car. Just when I was about to complete pressuring may last tank this morning the pressure gauge failed. Somehow it leaked the glycerine or oil out of the gauge and the needle was vibrating. I guess it is time to hunt for a new gauge.
 
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