What are the working principles of the blowdown valve?

1. The valve opens (drainage process) 1.1 Turn the handwheel valve stem counterclockwise to drive the valve core to move up gradually, the sealing surface is disengaged, and the guide seat on the valve core gradually moves out of the inner hole of the valve seat to form a narrow gap, and the medium passes through the valve seat The symmetrical orifice on the upper part enters the inside of the valve seat, and a small amount of medium can flow out through the narrow slit, gradually reducing the system pressure. 1.2 Continue to turn the handwheel counterclockwise, the valve core moves upward, the orifice on the guide seat moves out of the inner cavity of the valve seat, and more media are throttled through the guide seat and the valve sleeve and then discharged smoothly. 1.3 Continue to turn the handwheel counterclockwise, and the valve core moves up to the fully open position. At this time, the medium pressure is greatly reduced, and a large amount of impurities can be directly discharged from the valve sleeve orifice, and a vortex is formed at the inverted sealing seat, which is continuously cleaned. Sealing surface to prevent impurities from adhering to the sealing surface. 2. Valve closing process: 2.1 Turn the valve clockwise, the valve stem drives the valve core to move down, at this time the blowdown is over, the system pressure is low, the area of ​​the orifice on the valve sleeve gradually decreases, the guide sleeve is close to the valve seat, and changes The flow direction of the medium, the medium passes through the valve core and the valve as the sealing surface at a certain speed after throttling, and gradually strengthens the cleaning of the sealing surface. 2.2 Continue to turn the handwheel, the guide seat on the valve core enters the inner hole of the valve seat, forming a narrow slit throttling, because the sewage is nearing the end, the impurities in the medium are less, and the narrow gap between the guide sleeve and the valve seat prevents the remaining Small impurities flow into the sealing surface, and the medium quickly flows out through the narrow slit, which thoroughly cleans the sealing surface and ensures zero leakage when the sealing pair contacts. 2.3 Continue to turn the handwheel, the valve core and the sealing seat are in contact. achieve sealing. The above content is compiled according to the problems encountered by the students in their actual work for reference. If there are any problems, please communicate and correct them in time.