The self discharging valve seat (Figure 1) is also called the upstream sealing automatic pressure relief valve seat. Upstream sealing means that the upstream valve seat plays a sealing role when the gate is used. When the pipeline is under low pressure or no pressure, the spring set at the back of the valve seat provides the initial sealing preload to ensure the sealing performance under this state. When the pipeline is under normal pressure, the upstream valve seat is pushed to the spherical surface by the medium pressure to form a seal. Automatic pressure relief means that when the pressure in the middle chamber of the valve rises (usually 1.33 times higher than the nominal pressure according to API6D), the pressure in the middle chamber reverses the valve seat,

Model of midline butterfly valve The midline butterfly valve is actually a butterfly valve The structural form of the midline butterfly valve is a sealed central vertical plate, the whole butterfly plate and the valve seat are concentric within 360 ° circumference (midline), with two-way sealing function, so let's summarize the model of the midline butterfly valve