According to the sealing surface material, gate valves can be divided into two types: hard seal and soft seal. What is the difference between a soft seal valve and a hard seal valve:
Hard seal gate valve: The sealing materials on both sealing surfaces are metal materials, which is called “hard seal”. High temperature resistance, wear resistance, good mechanical properties such as: steel + steel; steel + copper; steel
+ Graphite; steel + alloy steel. The commonly used sealing materials are: 13Cr stainless steel, hard-facing hard alloy materials, sprayed tungsten carbide, etc. The sealing surface is relatively poorly sealed.
Soft seal gate valve: the seal pair is made of metal materials on one side and elastic non-metallic materials on the other side, which is called “soft seal”. The sealing performance of this kind of seal is good, but it is not resistant to high temperature, easy to wear, and has poor mechanical properties. Such as: steel + rubber; steel + PTFE, etc. Means that one side of the seal pair is made of materials with relatively low hardness. Generally speaking, the soft seal seat is made of non-metallic materials with certain strength, hardness and temperature resistance. It has good sealing performance and can achieve zero leakage, but it has a long life. Compared with the poor adaptability to temperature, the hard seal is made of metal, and the sealing performance is relatively poor, although some manufacturers claim that it can achieve zero leakage. The purpose of the invention of the soft sealing gate valve: to solve the problem of the valve seat and the sealing surface of the valve plate being corroded or deformed, the valve plate can automatically compensate for the pressure tight cover and the pressure automatic balance with the soft sealing gate valve, and solve the problem of the soft sealing material being damaged by friction The problem of the sealing surface, because the sealing sleeve of the gate valve can be replaced, greatly increasing the use of the valve.
Practical range of soft seal gate valve: diameter (p50-p400mm, pressure 2.5-4.0MPa, various normal temperature liquids less than 200℃).
The soft seal cannot meet the process requirements for some corrosive materials, and the hard seal can solve it!
These two kinds of seals can complement each other. In terms of tightness, the soft seal is relatively good, but now the tightness of the hard seal can also meet the corresponding requirements! The advantage of the soft seal is good sealing performance, but the disadvantage is that it is easy to age, wear, and has a short service life. The hard seal has a long service life, but the tightness is relatively worse than that of the soft seal.