With the wide use of butterfly valves, the characteristics of convenient installation, convenient maintenance and simple structure are becoming more and more obvious. Electric soft-seal butterfly valves, pneumatic soft-seal butterfly valves, and hard-seal butterfly valves have begun to replace electric gate valves and globe valves in more and more occasions. Valves are commonly used equipment for pipeline installation and industrial pumps to control the flow rate. There are many forms of valves. Butterfly valves are also commonly used valves. For valve sealing, what is the difference between soft-seal butterfly valves and hard-seal butterfly valves? Butterfly valve, also known as flap valve, is a kind of control valve with simple structure. Because of its convenient installation, convenient maintenance and simple structure, butterfly valve is favored by the majority of users, and its application is more and more extensive. But which one has more advantages, hard-sealed butterfly valve and soft-sealed butterfly valve, and how can we distinguish?


1. Soft sealing butterfly valve
Butterfly valve soft seal means: one side of the sealing pair is made of metal material, and the other side is of elastic non-metallic material. 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.
The soft seal seat is made of non-metallic materials with certain strength, hardness and temperature resistance. It has good performance and can achieve zero leakage, but its 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 to be able to achieve zero leakage. The soft seal cannot meet the process requirements for some corrosive materials. Hard seals can be solved, and the 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 advantages of soft seals are good sealing performance, but the disadvantages are easy aging, wear and short service life. Hard seals have a long service life, but the sealing performance is relatively poorer than soft seals.


2. Hard sealing butterfly valve
Butterfly valve hard seal means that both sides of the sealing pair are made of metal materials or other hard materials. 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 or surfacing, sprayed alloy.

The performance difference between soft sealing butterfly valve and hard sealing butterfly valve:

Hard sealing butterfly valve: The two sides of the sealing pair are made of metal materials or other hard materials, which are called "hard seals". This kind of seal has poor sealing performance, but has high temperature resistance, wear resistance, good mechanical properties and long service life.

Soft-seal butterfly valve: One side of the sealing pair is made of metal material, and the other side is of elastic non-metallic material, 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, has poor mechanical properties, and has a short service life.

The structure difference between soft sealing butterfly valve and hard sealing butterfly valve:

1. Structural differences: soft-seal butterfly valves are mostly centerline type, and hard-seal butterfly valves are 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 is used for low pressure-normal pressure, and hard seal can also be used in medium and high pressure conditions;

4. Sealing performance: Soft seal and triple eccentric hard sealing butterfly valve have better sealing performance, and the triple eccentric butterfly valve can maintain a good seal under high pressure and high temperature environment.

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

Doing a good job of distinguishing between hard-sealed butterfly valves and soft-sealed butterfly valves can help users choose suitable products and give full play to the advantages of products. In general, whether it is a hard-sealed butterfly valve or a soft-sealed butterfly valve, each has its own advantages and disadvantages. The important thing is to depend on the needs of the user, so it is very necessary to master the difference between the two.