Knife gate valve and globe valve are two commonly used shutting-off industrial valve. Today we are going to discuss the differences between knife gate valve and globe valve.
Belo valve is one professional Chinese supplier for knife gate valves and globe valves, like wafer knife gate valves, lug knife gate valves, flange knife gate valves, resilient seated knife gate valves, metal seated hard sealing knife gate valves; for globe valves, we have cast iron/ductile iron DIN globe valves, cast iron/ductile iron DIN bellows sealing globe valves.
The differences between knife gate valves and globe valves
1. Knife gate valve and globe valve have different structure. Especially the rising stem knife gate valve requires a higher height space, when we are choosing a rising stem knife gate valve, we should spare enough installation space from them. While the installation space for globe valve is relatively small.
For knife gate valve, with different stem structure, there are rising stem knife gate valve and non rising stem knife gate valve; for different body material used, there are cast iron knife gate valve, ductile iron knife gate valve, carbon steel knife gate valve, stainless steel knife gate valve.
2. Knife gate valve and globe valve have different seat sealing surface.
When the knife gate valve is opened and closed, the valve trim and the seat sealing surface always touch and rub against each other,so the seat sealing surface is easy to be damaged, especially when the knife gate valve is close to the closed state, the pressure difference between the front and the back of the valve trim is large, and the damage of the seat sealing surface is even more serious;
While once the valve disc of the globe valve is in the open state, there will be no contact between the valve seat and the raised surface of the valve disc, so the mechanical wear of the raised surface is small, but if the medium contains solid particles, it is easy to damage the raised surface. The raised surface on the valve seat of the knife gate valve has a certain self-sealing ability, and its valve trim is tightly contacted with the raised surface of the valve seat by the medium pressure to achieve tight sealing and no leakage. The trim slope of the wedge-shaped knife gate valve is generally 3-6°. the valve trim of the knife gate valve is easy to get stuck when the knife gate valve is forced to be close for many times or the temperature change too much. Therefore, for the high temperature and high pressure wedge knife gate valve, there is some certain special designs to prevent the valve trim from being stuck.
The globe valve can achieve sealing effect only by external force.with the same specification, working pressure, and the same driving device, the driving torque of the globe valve is 2.5-3.5 times that of the knife gate valve. The raised surface of the globe valve only touch each other when it is completely closed, and the relative movement between the forced closed trim and the raised surface is very small, so the damage to the raised surface is also very small.
3. The knife gate valve and globe valve have different flow resistance. The opening and closing force of knife gate valve is small. Knife gate valves are generally suitable for the working conditions which do not need to be opened and closed frequently, and maintain the knife gate valve to be fully opened and fully closed, knife gate valves are not suitable for adjustment and throttling.
However, the flow resistance of the globe valve is very large in the whole stroke, the unbalanced force is large, and the required driving force or torque is correspondingly much larger. But the globe valve is very suitable for adjusting and throttling fluid. For the high-speed flowing medium, when the knife gate valve is partially opened, it can cause the knife gate valve to vibrate, and the vibration may damage the raised surface of the knife gate valve and the valve seat, and throttling will cause the knife gate valve to suffer from the medium abrasion.
4. Knife gate valve and globe valve have different fluid flow direction design. For the knife gate valve, the medium can flow in from both directions, while for the globe valve,the medium will be required to flow in from one specific direction.
Compared with the knife gate valve, the globe valve has the advantages of compact structure, great sealing effect, and convenience for manufacturing and maintenance. The disadvantages of globe valve is that the liquid resistance is large, and the opening and closing force is large.
5. The knife gate valve and globe valve have different stroke distance. The stroke of the knife gate valve is larger than that of the globe valve.
6. The knife gate valve and globe valve have different maintenance process. The maintenance of the knife gate valve can not be done with the knife gate valve installed on the pipeline. While the valve seat and disc of most globe valve can be replaced without removing the entire globe valve from the pipeline, which is suitable for the conditions where the globe valve is welded together with the pipeline.
Of course, there are more differences between knife gate valves and globe valves. Before we decide to select knife gate valve or globe valve, we need to distinguish their similarities and differences better, so as to avoid mistakes. The application range of globe valve and knife gate valve is determined according to their characteristics. In the steam pipelines and large diameter water supply pipelines, because the fluid resistance is generally required to be small, knife gate valves are usually used.
With different driving device used, there are manual hand wheel operated knife gate valve, electric actuated knife gate valve, pneumatic cylinder operated knife gate valve, hydraulic actuated operated knife gate valve.
Belo Valve can supply DIN cast iron/ductile iron globe valves and DIN cast iron/ductile iron bellows sealing globe valves.
For more technical data about knife gate valves and globe valves, please contact us directly: