The hard sealing butterfly valve with metal materials on both sides of the sealing pair and elastic non-metallic materials on the other side is called "soft sealing". The sealing performance of this seal is good, but it is not resistant to high temperature, easy to wear and poor in mechanical properties. For example: steel+rubber; Steel+Teflon; Wait for rotor pump. The soft seal butterfly valve has the advantages of good sealing performance, but its disadvantages are easy aging, wear and short service life.

If both sides of the sealing pair are made of metal materials or other hard materials, it is called "hard seal". The sealing performance of this seal is poor, but it has high temperature resistance, wear resistance and good mechanical performance. 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 and spraying alloy). Hard seal butterfly valve has a long service life, but its sealing performance is relatively worse than soft seal.

Difference between soft seal butterfly valve and hard seal butterfly valve

1. Structural differences

Soft seal butterfly valves are mostly medium type, while hard seal butterfly valves are mostly single eccentric, double eccentric and triple eccentric.

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 - atmospheric pressure, hard seal can also be used in medium-high pressure and other working conditions.

4. Sealing performance

The sealing performance of soft seal and triple eccentric hard seal butterfly valve is better. The triple eccentric butterfly valve can maintain good sealing under high pressure and high temperature.

In view of the above characteristics, the soft seal butterfly valve is applicable to the two-way opening and closing and adjustment of the ventilation and dust removal pipeline, water treatment, light industry, petroleum, chemical and other industries. Hard seal butterfly valves are mostly used in heating, gas supply, gas, oil, acid and alkali environments.