Repair of diaphragm backpressure valve

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A diaphragm-type backpressure valve had leakage at its valve cover; no relevant materials were available, nor were there any data sheets or spare parts. Upon disassembly, it was found that the gasket between the upper valve cover and the valve seat had corroded and damaged, causing material to leak out through the plug holes and into the spring chamber of the diaphragm. The leakage occurred also through the balance hole at the top of the valve cover. A custom-made gasket was used to repair the issue and restore normal operation. The internal structure of the diaphragm-type backpressure valve is relatively simple: the lower valve seat serves as the inlet and outlet passage. There is a spring inside the upper valve cover, and an adjustment bolt is present at the top for regulating the backpressure. This bolt should not be altered, as this will ensure that the settings can be restored easily after disassembly. At the bottom of the spring, there is a pusher that comes into contact with the diaphragm; the diaphragm is fixed between the valve cover and the valve seat, serving to seal the liquid. If the diaphragm is damaged and no spare parts are available, a PTFE sheet of appropriate thickness can be used; this will hardly affect the set parameters. I won’t be able to upload pictures, please don’t laugh. I used to get help on forums quite often, so I’m sharing what I learned from this repair for reference only.