The dark stem gate valve can't see the rod , and the open stem gate valve can see the rod.
2.The lifting screw of the dark stem gate valve is only rotating without upper and lower movement, only one rod is exposed, its nut is fixed on the gate plate, and the lifting screw of the open rod flange gate valve is exposed, the nut is close to the handwheel and is fixed (no rotation and no axial movement), and the screw and the gate plate have only relative rotating motion and no relative axial displacement.
3.The handwheel and the stem are relatively motionless when the dark stem valve is switched on and off, and it is opened and closed by turning the stem at a fixed point to drive the disc up and down. The open stem valve is lifted or lowered by the screw drive between the stem and the handwheel. To put it simply, the open stem valve is the disc that moves up and down with the stem, and the handwheel is always at the fixed point.
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