I would like to ask about the working principles of gate valves, globe valves, ball valves, and air traps

OP, you can use search to look; there are quite a few on the forum. Here’s one to see how it works. http://bbs.hcbbs.com/viewthread.php?tid=151617&highlight=%B7%A7%C3%C5

Gate valves are used to shut off fluids; when fully open, the flow path is completely unobstructed, resulting in the lowest pressure loss for the fluid flow. Gate valves are typically suitable for applications where frequent opening and closing are not required, and where the gate plate needs to remain fully open or fully closed. Not suitable for use as a regulator or throttle. For media flowing at high speeds, partial opening of the gate plate can cause vibration in the gate, and this vibration may damage the sealing surfaces of the gate plate and the valve seat; moreover, throttling exposes the gate plate to erosion by the medium. The axis of the stem of the stop valve is perpendicular to the sealing surface of the valve seat. The valve stem has a relatively short opening or closing stroke, and it provides a very reliable shut-off action, which makes this type of valve highly suitable for shutting off or regulating flow. Once the valve disc of a throttle stop valve is in the open position, there is no longer any contact between its seat and the sealing surface of the valve disc, again ensuring a very reliable shut-off action; hence, this type of valve is very appropriate for use in shutting off or regulating flow as well as for throttling. Once a globe valve is in the open position, there is no longer any contact between its seat and the sealing surface of the disc; as a result, mechanical wear on these sealing surfaces is minimal. Moreover, since the seat and disc of most globe valves are easy to repair or have their sealing elements replaced without the need to remove the entire valve from the pipeline, this makes them very suitable for situations where the valve is welded to the pipeline. The flow direction of the medium changes as it passes through such valves; therefore, the flow resistance of globe valves is higher than that of other valves. The working principle of a ball valve is to use the rotating valve stem to open or close the valve. Ball valves are easy to operate, compact in size, and can be manufactured in large diameters. They offer reliable sealing, a simple structure, and are easy to maintain. The sealing surface and the ball itself remain in a closed state, making them resistant to erosion by the medium flowing through them; as a result, they are widely used in various industries.