What is the difference between a bidirectional hard seal butterfly valve and a regular butterfly valve?

What is the difference between a bidirectional hard seal butterfly valve and a regular butterfly valve?
Both bidirectional hard seal butterfly valves and ordinary butterfly valves belong to the category of butterfly valves, and their differences mainly lie in their structural materials and scope of use.
Firstly, the structural materials of bidirectional hard sealed butterfly valves are more durable and durable, usually made of materials such as cast iron, cast steel, stainless steel, etc. In contrast, the structural materials of ordinary butterfly valves are relatively light and thin, often made of materials such as aluminum alloy, copper alloy, and cast iron.
Secondly, the use range of bidirectional hard seal butterfly valves is wider because they can withstand greater pressure and temperature, and are suitable for high-strength, high-temperature, and high-pressure fluid control. Ordinary butterfly valves are mainly suitable for controlling general fluids.

In addition, the sealing performance of the bidirectional hard sealed butterfly valve is better because it uses hard materials as sealing components, which can effectively prevent fluid leakage. However, ordinary butterfly valves use soft materials such as rubber as sealing components, which have poor sealing performance and are prone to leakage under high temperatures and pressures.
Overall, both bidirectional hard seal butterfly valves and ordinary butterfly valves have their own advantages and disadvantages, and the specific selection should be determined based on actual needs. For high-strength, high-temperature, and high-pressure fluid control, it is recommended to use bidirectional sealed butterfly valves, while for general fluid control, ordinary butterfly valves can be chosen.