What are the advantages of rotary ball valves compared to butterfly valves and gate valves?
The rotary ball valve combines the functions and advantages of butterfly valves, hemispherical valves, gate valves, and globe valves, while also possessing its own unique and powerful functions and advantages. It is small in size, lightweight, easy to transport, install, maintain, and repair, and operates reliably. The rotary ball valve’s sealing principle is similar to that of a regular butterfly valve, possessing all the characteristics of a butterfly valve, but it also has its unique advantages. It adopts the sealing principle of an eccentric hemispherical valve, with a spherical sealing surface. The sealing pair is made of stainless steel or hard alloy material, and the structure is double eccentric. Because the valve seat uses a floating structure (the valve seat can float according to the deformation and displacement of the valve plate), it can achieve bidirectional sealing and is mainly used for shut-off and throttling in pipelines.
A gate valve (with a gate seat called a gate plate seat) is used to connect (fully open) or cut off (fully close) the medium in the pipeline. It is not allowed to be used for shut-off; during use, the gate should be avoided from being slightly opened, as the erosion of the high-speed flowing medium will accelerate the damage to the sealing surface. A gate valve is a type of valve where the gate plate moves up and down on a plane perpendicular to the center line of the gate seat channel, cutting off the medium in the pipeline like a gate.
A butterfly valve is a type of valve where the closing element (valve disc or butterfly plate) is a disc that rotates around the valve shaft to open and close. It is mainly used for shut-off and throttling in pipelines. The butterfly valve’s opening and closing element is a disc-shaped butterfly plate that rotates around its own axis within the valve body to achieve opening, closing, or regulation. The angle from fully open to fully closed is typically less than 90°. The butterfly valve and its stem do not have self-locking capability; a worm gear reducer is installed on the valve stem to position the butterfly plate. Using a worm gear reducer not only gives the butterfly plate self-locking capability, allowing it to stop at any position, but also improves the valve’s operating performance.
Comparing by action method:
Gate valves are linear-stroke valves, meaning the valve stem moves the valve plate vertically up and down. Due to their higher opening height, their opening and closing speed is slower. Ball valves and butterfly valves, on the other hand, are rotary-stroke valves, meaning the butterfly valve’s valve plate rotates 90° around the valve shaft to complete the opening and closing action. Therefore, the butterfly valve’s opening angle is only one-quarter of the channel diameter, resulting in rapid opening and closing.
Comparing by function and application:
Gate valves have low flow resistance and good sealing performance. Because the gate valve plate and the medium flow direction are perpendicular, if the gate valve is not fully open or closed, the medium’s scouring of the valve plate can cause it to vibrate, easily damaging the gate valve seal. Therefore, they are mostly used for shut-off in pipelines requiring strict sealing and not frequent opening and closing, and are not suitable for regulating pipeline medium parameters. Due to their slower opening and closing speed, they are also unsuitable for emergency shut-off situations. Gate valves typically use metal-sealed pairs. Due to their symmetrical sealing structure, they can achieve bidirectional sealing. Therefore, gate valves are wear-resistant and high-temperature resistant, and can be used in high-temperature, low-temperature, high-pressure, and low-pressure conditions. However, their large size, heavy weight, and high price limit their application range.
Rolling ball valves and butterfly valves not only have a shut-off function but also a regulating function. Butterfly valves open and close quickly and frequently, making them particularly suitable for applications requiring rapid opening or shut-off. Compared to gate valves, butterfly valves are smaller, lighter, and cheaper. In applications with limited installation space, butterfly valves are a better choice, saving space and allowing for larger diameters; DN300 and above butterfly valves are commonly used. They can also be used to transport media containing small particles or impurities. However, butterfly valves have a narrower pressure and temperature range. In many applications, butterfly valves are gradually replacing gate valves and have become the preferred choice for many users.
