Rising Stem Gate Valve vs Non Rising Stem Gate Valve
Aug 02,2022Read More
We all know that a gate valve needs to be installed to build a building, but the gate valve has two types of open rods and dark rods, and many users do not understand the situation. What is the difference between a rising stem gate valve and a dark stem gate valve? Let's take a look together.
Gate valves are usually designated as rising-stem and non-rising stem designs. The advantage of rising-stem valves is that they permit easy visualization as to whether a valve is open or closed. The advantage of the Non-Rising Stem, or NRS valves, is that the stem is protected from exposure to corrosive or other environmental conditions by the valve bonnet. Neither design has much impact on the actual valve function. Rising stem gate valves are usually made from cast or forged steel while non rising stem gate valves are more typically brass, bronze or cast iron. Non rising stem valves take up less space and rising stem valves require more space. In the rising stem gate valve, the round handle rotates a threaded shaft which is attached to its center. Turning the handle will cause the stem to rise as it opens the valve and descend as it closes the valve. With a rising stem gate valve it is easy to tell if the valve is open or closed by looking at the amount of stem that is exposed. If the handle is flush with the pipe (no exposed stem), the valve is closed. If a lot of stem is exposed, the valve is open.
This simple system has a couple of disadvantages which can be avoided compared with another type of gate valve: the non-rising stem gate valve. As for the non-rising stem gate valve, it is usually suitable for tight places where there is not enough room for the stem to raise, for example, places with underground pipes. The non-rising stem gate valve is fully open when the handle is rotated as far as possible to the left and fully closed when the handle is rotated as far as possible to the right. In both cases the handle is flush with the pipe because the mechanism inside the pipe opens and closes the valve without raising the stem. Another advantage to the non-rising stem gate valve is that it is easier to padlock. With the rising stem gate valve, two different size padlocks could be needed to lock the valve open and closed. With the non-rising gate valve one padlock is enough. But the disadvantage of a non rising stem valve is the fact that the screw threads that lift the gate are exposed to the fluid being controlled by the valve. This can cause problems if the fluid tends to foul the threads, so non rising stem valves are usually only used on clean liquids and gases.
Different shapes: the stem of the open industrial gate valve is directly exposed and can be seen directly, while the stem of the dark stem gate valve is set inside the valve body and cannot be seen directly. If you want to check the valve stem, you need to first Open the valve body.
The switching principle is different: the valve stem of the open stem gate valve is driven up and down through the valve stem and the steering wheel thread, while the valve stem and the steering wheel of the dark stem gate valve are relatively stationary, so when switching up and down, it can be directly rotated at a fixed point. , to realize the drive gate valve.
The method of lifting the gate is different: the stem of the rising stem gate valve is exposed, the nut is fixed on the handwheel, and the gate is lifted by rotating the screw. At this time, the screw and the gate are in relative rotational motion, and the surface of the gate valve can be seen. to the door type bracket. The nut of the dark stem gate valve is fixed on the gate, and the rotation of the screw itself is used to complete the action of lifting the gate, so from the appearance, the door clip cannot be seen.
The above difference between the open stem gate valve and the dark stem gate valve is introduced here, I hope to help you. There are obvious differences between the open stem gate valve and the dark stem gate valve in terms of working principle and appearance, so when purchasing, you must fully understand it to avoid unnecessary influence.
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