Should the butterfly valve use a soft seal or a hard seal?
Soft seal:
One side of the sealing pair is made of metal material, and the other side is made of elastic non-metallic material, which is called "soft seal".
This kind of seal has good sealing performance, but it is not resistant to high temperature, easy to wear, and has poor mechanical properties. Such as: steel rubber; steel PTFE, etc.
The soft sealing 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 its service life and adaptability to temperature are relatively poor.
Hard seal:
Both sides of the sealing pair are made of metal material or other harder materials, which are called "hard seals". This kind of seal has poor sealing performance, but has high temperature resistance, wear resistance and good mechanical properties.
Such as: steel steel; steel copper; steel graphite; steel alloy steel; (the steel here may also be cast iron, cast steel, alloy steel may also be surfacing, sprayed alloy).
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 seals can complement each other. In terms of tightness, soft seals are relatively good, but now the tightness of hard seals can also meet the corresponding requirements!
The advantage of soft seal is good sealing performance, but the disadvantage is easy aging, wear and short service life.
The hard seal has a long service life, but the sealing performance is relatively poorer than that of the soft seal.
The main differences in structure are as follows:
1. Structural differences: soft-seal butterfly valves are mostly mid-line hard seals, mostly single-eccentric, double-eccentric, and triple-eccentric butterfly valves.
2. Temperature resistance: soft seal is used in normal temperature environment. Hard seal can be used in low temperature, normal temperature, high temperature and other environments
3. Pressure: soft seal low pressure - normal pressure, hard seal can also be used in medium and high pressure conditions
4. Sealing performance: Soft seal and triple eccentric hard seal butterfly valve have better sealing performance, and triple eccentric butterfly valve can maintain a good seal under high pressure and high temperature environment.