Views: 356 Author: Site Editor Publish Time: 2020-08-25 Origin: Site
The gate valve is an opening and closing gate. The direction of movement of the gate is perpendicular to the direction of the fluid. The gate valve can only be fully opened and fully closed, and cannot be adjusted and throttled. Do you know the difference between opening gate valve and a closing gate valve?
The hidden lever gate valve is also called a rotary lever gate valve. The stem nut is set on the gate, and the handwheel rotates to drive the stem to rotate, and the gate is lifted. Usually, there is a trapezoidal thread at the bottom end of the stem. Through the bottom thread of the valve and the guide groove on the valve disc, the rotary motion is changed into a linear motion, that is, the operating torque is changed into an operating thrust.
When the height of the gate is equal to 1: 1 of the valve diameter, the fluid channel is completely unblocked. In actual use, the apex of the valve stem is taken as the mark, and its fully open position is used. In order to consider the lock-up phenomenon caused by temperature changes, it is usually opened to the top position, and then back to 1/2 ~ 1 turn, as the position of the fully open valve.
The advantage of this structure is that the height of the gate valve always remains unchanged, so the installation space is small, which is suitable for gate valves with large calibers or restricted installation space. This structure should be equipped with an opening and closing indicator to indicate the degree of opening and closing.
The disadvantage of this structure is that the valve stem thread is not only unable to lubricate, but also directly receives medium erosion and is easily damaged.
The lifting screw of the closed rod flange gate valve only rotates without moving up and down. Only one rod is exposed. The nut is fixed on the gate. The gate is lifted by the rotation of the screw. There is no visible door frame. The lift screw of the lever flange gate valve is exposed, and the nut is close to the hand wheel and is fixed. The gate is lifted by rotating the screw. The screw and the gate only have relative rotational movement without relative axial displacement.
Steering wheel and valve stem are connected together and are relatively immovable when valve is opened and closed. The valve stem is lifted and lowered by the valve stem at a fixed point to complete opening and closing. The open stem valve lifts or lowers the valve disc through the threaded transmission of the valve stem and the steering wheel. The simple point is that the opening valve is a valve disc that moves up and down together with the stem, and the steering wheel is always at a fixed point.
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