In industrial fluid control systems, flow passage design stands as a core factor determining valve operational performance, directly influencing key metrics such as flow capacity, medium erosion resistance, sealing reliability and maintenance convenience. This article focuses on five widely used valve types: ball valve, eccentric rotary valve, butterfly valve, knife gate valve and slide valve-systematically analyzing their flow passage structural characteristics, inherent advantages and practical application limitations. The aim is to provide technical reference for rational valve selection in different industrial scenarios and optimize fluid system operation efficiency.
1. Ball Valve
Structural Advantages
When fully open, it has a full bore without any dead corners, so the medium will not cause scouring and wear to other valve components when passing through.
It has good sealing performance when closed, and metal sealing can reach Class V or higher.
Disadvantages
When the valve is in the half-open state, materials may enter the valve cavity. Considering the short opening and closing time, the impact may not be significant in a short period, but problems such as valve stem seizure or ball jamming will inevitably occur after long-term use.
2. Eccentric Rotary Valve
The eccentric rotary valve evolved from the ball valve can also be used as a high-performance on-off valve. It does not have the valve cavity of the ball valve, so it can solve the problem of material accumulation in the valve cavity.
Disadvantages
When fully open, the flow passage of the eccentric rotary valve is not a smooth cylindrical full bore. When materials pass through, especially solid particulate materials, they will cause scouring and wear to the valve stem and other valve components.
3. Butterfly Valve
The butterfly valve is used to regulate the flow of liquids, gases and steam. It has self-cleaning ability, so it can be widely used for fluids with suspended particles and thick turbid slurries. It is especially suitable for occasions with large caliber, large flow and low pressure difference. Meanwhile, the butterfly valve is also commonly used for on-off purposes.
Disadvantages
Even in the fully open state, the valve disc of the butterfly valve is completely exposed to the medium, so it suffers severe scouring and has a short service life.
When closing, the valve disc is easily jammed by solid particulate materials, which may cause wear damage to the material carrier and affect the closing effect.
4. Knife Gate Valve
Advantages
It has a small flow resistance coefficient. When fully open, the flow passage is a cylindrical full bore, so other valve components will not be scoured by the medium to cause mutual damage.
Large-caliber valves are easy to select and relatively economical in price.
Disadvantages
When closing, the valve stem has a long stroke and the height dimension is relatively large. It is difficult to ensure complete sealing, the sealing surface is prone to scuffing, and the working conditions are poor. In wedge gate valves, the assembly of the wedge gate disc and the valve body is complicated.
Material is easy to accumulate at the bottom of the knife gate. When closing, it is easy to damage the material carrier and affect the closing effect.
Due to structural limitations, external leakage is prone to occur.
5. Slide Valve
The structural feature of the slide valve is that the slide plate runs through both ends of the valve body, and there is a hole in the middle of the slide plate.
When the slide valve is fully open, it also has a cylindrical full-bore flow passage and will not be scoured by the medium. When closing, since the slide valve has no so-called valve seat, it will not cause medium accumulation or material damage. Moreover, because the slide valve does not have a valve cavity like the ball valve, it will not cause material accumulation and thus problems such as jamming.
Possible Disadvantages
When the slide valve is closed right at the position of the circular hole, a small amount of material may be temporarily brought into the valve. However, when the valve is opened next time, the material will be brought back into the pipeline along the original path, so no material accumulation will occur inside the valve.
Thank you for your reading.
