Difference between Rising Stem & Non-rising Stem Gate Valves
Do you know the difference between rising stem gate valves and non-rising stem gate valves? Let's see it in this article.
What are the structural features of gate valves?
The gate valve has the characteristics of small fluid resistance, applicable pressure, temperature range, etc. It is one of the most commonly used cut-off valves, in order to cut off or connect the medium in the pipeline. Diameter shrinkage can reduce the size of parts. The force required to open and close, and expand the application range of parts. However, after diameter shrinkage, fluid resistance loss increases. Cast iron is widely used in low-pressure gate valves in China, and serious problems such as frozen crack of the valve body and shedding of the gate plate often occur in cast iron gate valves. The carbon steel valve stem of cast iron gate valves is easy to rust. The quality of packing gasket is poor, and the internal and external leakage is serious.
Gate valves can be divided into the following types according to the stems.
1. Rising stem gate valves: the stem nut on the valve cover or bracket, open and close the gate with rotating stem nuts to achieve the lifting of the valve stem. This structure is beneficial to the lubrication of the stem. The degree of opening and closing is obvious, so it is widely used.
2. Non-rising stem gate valves: the stem nut is in the valve body, which direct contact with the medium. We open and close the gate plate by rotating the stem. The advantage of this structure is that the height of the gate valve always remains the same, so the installation space is small. It is suitable for large diameter or the installation space is limited by the gate valve. The structure should be equipped with an open and close indicator to indicate the degree of opening and closing. The disadvantage of this structure is that the stem thread can not only be lubricated, but also directly corroded by the medium, which is easy to damage.
The main differences between rising stem gate valves and non-rising stem gates are as follows.
1. The lifting screw of the non-rising flanged gate valve is only rotated without moving or moving down. Only a rod is exposed. The nut is fixed on the gate plate, and the gate plate is lifted by the rotation of the screw, without the visible door frame. The lifting screw of the flanged gate valve is exposed, and the nut is fixed close to the handwheel (neither rotation nor axial movement), and the gate plate is lifted by rotating the screw. The screw and the gate plate have only relative rotating motion but no relative axial displacement, and the appearance is a portal bracket.
2. We can not see the screw on the non-rising stem gate valve, while we can see it on the rising stem gate valve.
3. The steering wheel and valve stem are connected together relatively immobile when the non-rising stem valve is on and off. It is opened and closed by turning the valve stem at a fixed point to drive the valve disc upward and down to complete the opening and closing. The stem valve is threaded to the steering wheel to lift or lower the disc. The simple point is that the stem valve is connected with the valve stem to do up and down movement. The steering wheel is always at a fixed point.
What are the structural features of gate valves?
The gate valve has the characteristics of small fluid resistance, applicable pressure, temperature range, etc. It is one of the most commonly used cut-off valves, in order to cut off or connect the medium in the pipeline. Diameter shrinkage can reduce the size of parts. The force required to open and close, and expand the application range of parts. However, after diameter shrinkage, fluid resistance loss increases. Cast iron is widely used in low-pressure gate valves in China, and serious problems such as frozen crack of the valve body and shedding of the gate plate often occur in cast iron gate valves. The carbon steel valve stem of cast iron gate valves is easy to rust. The quality of packing gasket is poor, and the internal and external leakage is serious.
Gate valves can be divided into the following types according to the stems.
1. Rising stem gate valves: the stem nut on the valve cover or bracket, open and close the gate with rotating stem nuts to achieve the lifting of the valve stem. This structure is beneficial to the lubrication of the stem. The degree of opening and closing is obvious, so it is widely used.
2. Non-rising stem gate valves: the stem nut is in the valve body, which direct contact with the medium. We open and close the gate plate by rotating the stem. The advantage of this structure is that the height of the gate valve always remains the same, so the installation space is small. It is suitable for large diameter or the installation space is limited by the gate valve. The structure should be equipped with an open and close indicator to indicate the degree of opening and closing. The disadvantage of this structure is that the stem thread can not only be lubricated, but also directly corroded by the medium, which is easy to damage.
The main differences between rising stem gate valves and non-rising stem gates are as follows.
1. The lifting screw of the non-rising flanged gate valve is only rotated without moving or moving down. Only a rod is exposed. The nut is fixed on the gate plate, and the gate plate is lifted by the rotation of the screw, without the visible door frame. The lifting screw of the flanged gate valve is exposed, and the nut is fixed close to the handwheel (neither rotation nor axial movement), and the gate plate is lifted by rotating the screw. The screw and the gate plate have only relative rotating motion but no relative axial displacement, and the appearance is a portal bracket.
2. We can not see the screw on the non-rising stem gate valve, while we can see it on the rising stem gate valve.
3. The steering wheel and valve stem are connected together relatively immobile when the non-rising stem valve is on and off. It is opened and closed by turning the valve stem at a fixed point to drive the valve disc upward and down to complete the opening and closing. The stem valve is threaded to the steering wheel to lift or lower the disc. The simple point is that the stem valve is connected with the valve stem to do up and down movement. The steering wheel is always at a fixed point.
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