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December 10, 2019

Common problems in installation and use of plastic butterfly valve

There are some common problems in the installation and use of PVC Butterfly Valve.


1.The valve plate cannot be fully opened because the structural length of PVC BUTTERFLY VALVE is short, and the valve plate cannot be opened when it touches the flange surface during the opening process. This problem happens on large size Butterfly Valve especially above dn400. to solve this, a spacer ring need to be installed between the PVC butterfly valve and the flange.


2.The sealing surface of butterfly valve leaks. Sometimes the PVC butterfly valve will leak after using a period of time. This is because there are problems in the design of some butterfly valve seats. After long-term use, the valve seats are squeezed and deformed seriously, resulting in the loosen of flange bolts. The maintenance people have to tighten the bolts again. Our butterfly valve body is designed with a seat fixing groove, this will reduce the extrusion of the valve seats deformation.


3.valve shaft leaks. the valve seat of PVC butterfly valve will be deformed after long-term use. At this time, the medium will leak into the valve shaft, which is a problem of many PVC butterfly valves. Therefore, the material of the valve shaft is very important. If the valve stem is made of steel, it is easy to rust. In the long term, it make increase of the valve torque, cause the leakage from the valve stem, even make the valve stuck, and the valve stem broken down.


4.The leakage from the valve stem. This leakage is mainly from the valve stem head. There are many reasons for this problem. First, the valve stem is rusted, second, the sealing ring at the top of the valve stem fails, and third, the gap between the valve stem and the valve body is too large. In order to solve this problem, our valve bodies are all machined to ensure that the dimension of the valve body and the valve stem are closely matched. Secondly, a compression ring is designed at the top of the valve stem to prevent the valve stem from popping out of the valve body under pressure.


5. Leakage from valve plate. this is mainly caused by abrasion of valve sealing surface or aging and cracking of valve seat rubber. Because PVC butterfly valve adopts EPDM rubber valve soft seal, if there are slit in the medium, the rubber will be worn, and the sealing surface will fail over time, resulting in leakage. On the other hand, the aging and cracking of EPDM rubber will also cause valve plate leakage, so the quality of EPDM material is also very important.
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