在單芯的情況下，如果介質是流動開放型，則閥的穩定性好，但是如果介質是流動封閉型，則閥的穩定性低。雙座閥有兩個滑閥，下滑閥關閉流量，上滑閥打開流量。因此，當使用小開口工作時，流量關閉滑閥會引起閥振動。這就是雙座閥不能用于小開度工作的原因所在。

In the case of a single core, if the medium is a flow open type, the stability of the valve is good, but if the medium is a flow closed type, the stability of the valve is low. The double seat valve has two slide valves, with the sliding valve closing the flow rate and the upper slide valve opening the flow rate. Therefore, when working with a small opening, the flow closing slide valve will cause valve vibration. This is why double seat valves cannot be used for small opening operations.

為什么雙密封閥不能當作切斷閥使用

Why dual seal valves cannot be used as shut-off valves

雙座閥芯的優點是平衡力雙密封閥結構，允許壓差大，而它突出的缺點是兩個密封面不能同時良好接觸，造成泄漏大。當人工強行用于切割時，效果顯然不好。不建議進行許多改進(例如雙密封套筒閥)。

The advantage of a dual seat valve core is the balanced force dual seal valve structure, which allows for a large pressure difference. However, its prominent disadvantage is that the two sealing surfaces cannot make good contact at the same time, resulting in large leakage. When manual force is used for cutting, the effect is obviously not good. It is not recommended to make many improvements (such as double sealed sleeve valves).

什么直行程的自力式壓力調節閥防堵性能差，角行程閥防堵性能好

What kind of straight stroke self operated pressure regulating valve has poor anti blocking performance, while angle stroke valve has good anti blocking performance

直行程閥芯垂直節流，介質水平流入和流出。閥腔中的流路不可避免地會旋轉，這會使閥的流路變得非常復雜(看起來像是反向的S型)。因此，有許多死區為媒體沉淀提供了空間，并且隨著事情的進展，它們會造成堵塞。四分之一轉閥的節氣門方向是水平的。介質水平流入和流出，因此很容易臟介質。同時，流路簡單，并且存在用于介質沉降的空間。由于尺寸小，所以角行程閥防堵性能好。

The straight stroke valve core is vertically throttled, and the medium flows in and out horizontally. The flow path in the valve chamber inevitably rotates, which makes the flow path of the valve very complex (looking like a reverse S-shape). Therefore, there are many dead zones that provide space for media sedimentation, and as things progress, they can cause blockages. The throttle direction of the quarter turn valve is horizontal. The medium flows in and out horizontally, making it easy to remove dirty media. Meanwhile, the flow path is simple and there is space for medium settlement. Due to its small size, the angle stroke valve has good anti clogging performance.

為什么直行程自力式壓力調節閥閥桿較細

Why is the stem of a straight stroke self operated pressure regulating valve thinner

它涉及簡單的機械原理：高滑動摩擦力和低滾動摩擦力。直行程閥的閥桿向上和向下移動，填料被輕微壓縮，從而使閥桿變得非常緊密，填料的回流差較大。因此，閥桿設計得非常小，填料使用低摩擦系數的PTFE填料來減少反沖，但是閥桿很薄，容易彎曲，填料成為一個問題。壽命短的此問題的方法是使用行程閥桿或1/4回轉閥。其閥桿的厚度是直閥閥桿的厚度的23倍，并選擇了壽命長的石墨填料。閥桿剛度好，填料壽命長，其摩擦力矩反而小、回差小。

It involves simple mechanical principles: high sliding friction and low rolling friction. The stem of the straight stroke valve moves up and down, causing the packing to be slightly compressed, making the stem very tight and resulting in a large backflow difference of the packing. Therefore, the valve stem is designed very small, and PTFE packing with low friction coefficient is used to reduce backlash. However, the valve stem is thin and prone to bending, making the packing a problem. The solution to this problem with a short lifespan is to use a stroke valve stem or a 1/4 turn valve. The thickness of its valve stem is 2 to 3 times that of a straight valve stem, and graphite packing with a long service life is selected. The valve stem has good stiffness and long packing life, but its friction torque is actually small and the backlash is small.