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Understand the difference between butterfly valve seat

Soft/hard/lined in the valve body
In the selection of butterfly valves, we often talk about the hard backrest, soft backrest and lining glue. The biggest difference between these three is the installation method of the valve body and the sealing material, which is reflected in the difference between the structural design of the valve body and the shape of the valve seat.
First of all, let's take the valve body of DN100 as an example. Let's intuitively observe the difference between the valve body.

The corresponding valve seat is different
First of all, what is the valve seat?
The valve seat is a detachable part inside the valve, which is used to support the fully closed position of the valve plate and form a sealing ring. Generally, the diameter of the valve seat is the maximum circulation diameter of the valve.
The valve seat of the butterfly valve is made of a wide range of materials, all kinds of rubber plastics and metal materials can be used as valve seat materials;
For example: EPDM, NBR, NR, PTFE, PEEK, PFA, SS315, STELLITE, FPM, SI, CR, natural glue, Haibolong, white ethylpropyl, fluoridine, wear-resistant Dingqing, silicone, German ethylene propylene, food glue.


Hard backrest valve seat
The material is composed of the outer rubber wrapped on the hard backrest. The installation method is to use a professional valve assembly platform to press the valve seat into the valve body through the machine. At the same time, the valve seat is also classified into ordinary type and waterline type.
Soft backrest valve seat
The whole material is only composed of rubber, so the high elasticity is also called the backrest seat. Its installation method is also more convenient for workers to repair, replace and disassemble.
Rubber-lined butterfly valve
The lining ring of the rubber-lined butterfly valve is integrated with the valve body as a whole and is made in batches by large-scale equipment. Compared with the traditional butterfly valve, this kind of butterfly valve has the advantages of high temperature resistance, light operation, no friction, good sealing performance and long service life of the butterfly valve. Therefore, it is now widely used in fire protection In engineering systems such as papermaking, textile, medical treatment, industrial water, urban sewage, gas, natural gas, liquefied petroleum gas, urban gas, hot and cold air, chemical smelting and power generation environmental protection, the pipelines of various corrosive and non-corrosive fluid media are used to regulate and cut off the flow of the medium.
Partial display of the finished butterfly valve
In the on-site installation, it is necessary to choose flat welding flanges or butterfly valve flanges according to different valve body structures.
1. The connection size of butterfly valve flange and flat welding flange is the same. The difference is that the size of the inner diameter is different.
2. The butterfly valve flange can be better combined with the rubber ring of the butterfly valve to ensure the tightness of the installation position.
The following shows the appearance of different valve seats on the butterfly valve body after installation (all pictures are live photos of the product)
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