Hard seal butterfly valves are made of metal materials or other harder materials on both sides, which are called "hard seals". This kind of seal has poor sealing performance, but high temperature resistance, wear resistance, and good mechanical properties. For example: steel + steel ;Steel+Copper;Steel+Graphite;Steel+Alloy Steel; (The steel here may also be cast iron, cast steel, alloy steel or surfacing, sprayed alloy).
The characteristics and differences of soft and hard sealing butterfly valves
Hard seal butterfly valve: The two sides of the sealing pair are made of metal materials or other harder materials are called "hard seals". This kind of seal has poor sealing performance, but high temperature resistance, wear resistance, and good mechanical properties. For example: Steel+steel; steel+copper; steel+graphite; steel+alloy steel; (the steel here may also be cast iron, cast steel, alloy steel or surfacing, sprayed alloy).
Soft seal: The two sides of the seal pair are made of metal materials on one side and elastic non-metallic materials on the other side, which is called "soft seal". This kind of seal has good sealing performance, but it is not resistant to high temperatures and is easy to wear. The mechanical properties are poor, such as: steel + rubber; steel + tetrafluoropolyethylene, etc.
The soft sealing butterfly valve means that one side of the sealing pair is made of materials with relatively low hardness. Generally speaking, the soft sealing seat is made of non-metallic materials with certain strength, hardness and temperature resistance. The sealing performance is good and can be achieved to zero. Leakage, but the service life and adaptability to temperature are relatively poor. 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 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.