Pneumatic double-seat control valve, as the name implies, has two valve cores and two valve seats in the valve body. It adopts a double-guide structure and is mainly composed of a multi-spring straight-stroke pneumatic actuator and a straight-through double-seat control valve body. The pneumatic double-seat control valve is generally used. Under the requirement of pressure compensation, the pressure compensation and valve shut-off are realized by using the two sealing lines on the spool barrel to seal at the same time.
Pneumatic double seat regulating valve performance and application:
The pneumatic double-seat control valve has the characteristics of compact structure, large valve capacity and accurate flow characteristics, and can be used in harsh working conditions. The rated flow coefficient is larger than that of the single seat valve of the same diameter, but the leakage page is larger than that of the single seat valve. It is suitable for clean medium occasions where the requirements for leakage are not strict and the pressure difference between the front and rear of the valve is large. Pneumatic double-seat control valve is widely used in industrial control departments such as petroleum, chemical, pharmaceutical, metallurgy, and power plants, mainly controlling gas, liquid, and steam. other medium.
Working principle of pneumatic double-seat control valve:
The valve seat of the pneumatic double-seat control valve has two valve cores, upper and lower. The fluid flows in from the left side of the valve body, and flows out from the right side after passing through the valve seat and the valve core. It can flow more media than the single-seat control valve with the same nominal diameter, and the flow capacity is increased by about 20% to 25%. The force of the medium acting on the upper and lower spools can cancel each other, so the unbalanced force is small and the operating pressure difference is large.
Dynamic diagram of working principle of pneumatic double-seat control valve:
However, due to the complicated medium flow path of the valve, the erosion and cavitation damage to the valve body will be serious when used in a high pressure difference; the pneumatic double-seat control valve is not suitable for the adjustment of high-viscosity media and fibrous media. In addition, because the upper and lower valve cores are not easy to close tightly at the same time, the leakage is large when closed. However, it has a strong flow capacity and allows the use of a large differential pressure, which is larger than that of a single-seat valve of the same diameter, and is suitable for occasions with high leakage requirements and high differential pressure.