The gate valve is a kind of valve used on the water system pipeline. It can be installed on production pipelines such as industry and agriculture, and can be used as a communication and cut-off medium. There are also many types of gate valves. The most common classification method is based on the structure. There are clear gate valves and dark gate gate valves. In addition, it can be divided into hard seal gate valve and soft seal gate valve according to the sealing surface material. We all know that the structure of the butterfly valve is very simple, and the size of the gate valve is larger than that of the butterfly valve, and its structure is more complicated than the butterfly valve. This article will give you a detailed description of the gate valve structure and the internal structure of the gate valve.
The gate valve is a valve with the shutter as the opening and closing member. The gate moves up and down along the vertical direction of the center line of the valve body passage, and the direction of movement and the direction of the medium flow are also perpendicular to each other. The gate valve is composed of a valve body, a valve seat, a valve stem, a gate, a valve cover, a sealing ring and the like. Common gate valves are driven by handwheels, in addition to which electric or pneumatic actuators can be installed to automate gate valves. The gate valve is installed on the pipeline and can only be fully opened and fully closed. It is used to cut off the medium flow and cannot be used as conditions and control flow.
Because of the special structure of the gate valve, when the gate valve is fully open and fully closed, the stroke is large, and the opening and closing time is long, especially during manual operation, which is time consuming, so the gate valve is usually installed on the pipeline that does not need to be opened and closed frequently. . In addition, the valve body passage inside the gate valve is straight-through, the medium can flow in both directions, and when the gate of the gate valve is fully opened, the flow resistance in the valve body passage tends to zero, and the flow resistance is very small.
The ring stem gate valve means that the valve stem of the gate valve is exposed, and the thread on the valve stem is also exposed. When the handwheel is rotated, the gate will move linearly with the valve stem, also called the lifter gate valve. The lifting rod of the open gate valve has a trapezoidal thread, which can change the rotary motion into a linear motion through the nut at the top of the valve and the guide groove on the valve body, that is, the operating torque becomes the operating thrust. Because the stem is exposed, the open gate valve can be used as a very obvious switch mark, which means that the valve can be opened and closed directly through the lift of the valve stem.
The non ring stem gate valve is different from the open rod gate valve in that the valve stem is inside the valve, and the thread on the valve stem is also located inside the valve body. The operation of the dark-rod gate valve is to manually rotate the valve stem to select the original position, and the ram is lifted and moved by the thread on the valve stem. Therefore, the dark rod gate valve is also called the rotary rod gate valve. Since the dark rod gate valve is built in, the opening and closing state of the dark rod gate valve cannot be directly observed, and it is generally until the switch is turned.
In the actual use process, in order to consider the temperature change, the locking phenomenon occurs, whether it is the ring stem gate valve or the non ring stem gate valve, usually at the position of the opening to the apex, and then back to 1/2-1 circle as the position of the fully open valve.