Hard seal butterfly valve, also known as flap valve, is a regulating valve with simple structure. At the same time, it can also be used for on-off control of low-pressure pipeline medium. The hard seal butterfly valve mainly plays the role of cutting off and throttling on the pipeline. The opening and closing part of butterfly valve is a disc-shaped butterfly plate, which rotates around its own axis in the valve body, so as to achieve the purpose of opening, closing or adjustment. The hard sealing butterfly valve is applicable to pipelines conveying various corrosive and non corrosive fluid media in generator, gas, steam, natural gas, urban gas, hot and cold air, chemical smelting engineering and power generation environmental protection system, and is used to regulate and cut off the flow of media.
As one of the most important block valves, stop valve plays an important role in the field of aerospace. As an important component of aerospace equipment, stop valve realizes the functions of medium transportation, stop and regulation. Its sealing performance directly affects the safe and reliable operation of aerospace equipment. The research on the influencing factors and laws of the sealing characteristics of typical stop valves has guiding significance for the structural design of valve sealing pair, so as to improve the sealing performance and reliability of the valve.
When the gate valve is closed, the sealing surface can be sealed only by the medium pressure, that is, the sealing surface of the gate valve can be pressed to the valve seat on the other side only by the medium pressure to ensure the sealing of the sealing surface, which is self sealing. Most gate valves are forced sealed, that is, when the valve is closed, the gate shall be forced to the valve seat by external force to ensure the tightness of the sealing surface.
The valve whose opening and closing parts open or close by the force of medium flow to prevent medium backflow is called check valve. The check valve is an automatic valve, which is mainly used on the pipeline with one-way flow of medium. The medium is only allowed to flow in one direction to prevent accidents.