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What is the difference between imported open gate valve and dark rod gate valve?

The gate valve can be divided into: the open gate valve and the dark rod gate valve according to the structure of the valve stem.
1. Open gate valve: The stem nut is on the bonnet or bracket. When opening and closing the gate, use the rotary stem nut to raise and lower the stem. This structure is advantageous for the lubrication of the valve stem, and the degree of opening and closing is obvious, so it is widely used.
2, dark rod gate valve: stem nut in the valve body, direct contact with the medium. When opening and closing the shutter, use a rotary valve stem to achieve. The advantage of this structure is that the height of the gate valve remains the same, so the installation space is small, and it is suitable for large-diameter or gate valves with limited installation space. This structure is equipped with an opening and closing indicator to indicate the degree of opening and closing. The disadvantage of this type of construction is that the stem thread is not only lubricated, but also directly etched by the medium and is easily damaged.
The main difference between the open gate valve and the dark gate valve:
1. The lifting screw of the dark rod flange gate valve only rotates without moving up and down. The exposed one is only a rod. The nut is fixed on the gate plate. The gate is lifted by the rotation of the screw. There is no visible gantry. The lifting screw of the open-face flange gate valve is exposed, the nut is close to the hand wheel and is fixed (not rotating or axially moving), and the shutter is raised by rotating the screw, and the screw and the shutter have only relative rotational motion. No relative axial displacement, the appearance is a door bracket.
2, the dark rod valve is invisible to the screw, and the bright rod is able to see the screw.
3. When the dark rod valve is switched, the steering wheel and the valve stem are connected together and relatively stationary. It is rotated by the valve stem at a fixed point to drive the valve flap up and down to complete the opening and closing. The stem valve lifts or lowers the flap by threading the stem and steering wheel.
To put it simply, the stem valve is the valve flap that is moved up and down together with the valve stem, and the steering wheel is always at a fixed point.

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