Gate valves can be divided into:

1, open rod gate valve:

Open stem gate valve: The stem nut is on the cover or bracket. When opening and closing the gate plate, the stem can be lifted or lowered by rotating the stem nut. This structure is favorable to stem lubrication, the degree of opening and closing is obvious, so it is widely used.

Usually there are trapezoidal threads on the lifting rod, through the nut at the top of the valve and the guide groove on the body, the rotary motion into straight motion, that is, the operation torque into the operation thrust.

The opening and closing part of the gate valve is the gate plate, the movement direction of the gate plate is perpendicular to the direction of the fluid, the gate valve can only be fully opened and closed, can not be adjusted and throttled.

2, dark rod gate valve:

Dark rod gate valve is also called rotating rod gate valve (also known as dark rod wedge gate valve). The stem nut is in the valve body in direct contact with the medium. To open and close the gate, rotate the stem.

The opening and closing part of the dark stem gate valve is the gate plate, the movement direction of the gate plate is perpendicular to the direction of the fluid, the gate valve can only be fully opened and closed, can not be adjusted and throttled.

The stem nut is located on the gate plate, and the handwheel turns to drive the stem to rotate and lift the gate plate. Usually there is a trapezoidal thread at the bottom of the stem. Through the thread at the bottom of the valve and the guide groove on the valve disc, the rotary movement is changed into a linear movement, that is, the operating torque is changed into the operating thrust.

The main differences between open rod gate valves and dark rod gate valves are as follows:

1, the lifting screw of the dark rod gate valve is only rotating and no upper and lower movement, the exposed is only a rod, its nut is fixed on the gate plate, through the rotation of the screw to lift the gate plate, there is no visible frame; The lifting screw of the open-rod gate valve is exposed, the nut is close to the handwheel and is fixed (no rotation and no axial movement), the gate is lifted by rotating the screw, the screw and the gate only have relative rotation movement but no relative axial displacement, and the appearance is a door shaped bracket.

2, the dark rod gate valve can not see the lead screw, and the open rod can see the lead screw.

3. The steering wheel and the valve stem are connected together when the dark stem gate valve is switched on and off. It is driven by the valve stem turning at the fixed point to lift the valve disc up and down to complete the opening and closing. Open STEM GATE valves raise or lower the disc by THREADING the stem to the STEERING wheel. The simple point is that the open stem gate valve is the disc connected to the stem moving up and down together, the steering wheel is always fixed point.