Ball valves and butterfly valves are often used by engineers to control the flow of gas or liquid. They are both inexpensive and durable quarter-turn rotary valves. Both are excellent at regulating flow at a wide range of temperatures. What’s the difference between a ball and a butterfly valve?.
They each have unique characteristics that make them ideal for specific applications despite their subtle differences. Butterfly valves or ball valves may be better suit for a particular project based on factors such as pressure differences, seal quality, and supply pipe size.
Ball Valves
Floating balls have holes drilled through them, which function as ball valves. If the valve is activate, the hole aligns in such a way that it blocks, partially blocks, or completely opens the flow of liquid or gas. Ball valves offer several benefits, including a tight seal that is ideal for gas flow applications. These are generally use in liquid or gas lines with a diameter of fewer than six inches. If there is high pressure on the supply side, ball valves offer almost no resistance when they are turning. Depending on the design, there may be no pressure drop. Ball valves can operate in temperatures ranging from -30°C to 230°C. There are several types of ball valves, including:
- Full-port ball valve: As the hole in the ball is the same size as the pipeline, the flow is uninterrupted. No friction loss occurs due to different opening sizes.
- Reduced-port ball valve: Because the hole in the ball is slightly smaller than the pipe, the flow is somewhat restricted. The design increases flow velocity and makes the valve less expensive.
- V-port ball valve: The ball or seat is V-shaped in this design. As the valve is activated, the small end of the V opens first, ensuring a more stable flow. Many people use these valves when they need more control or high velocity. They tend to have a more sturdy construction that can withstand high velocities that can ruin another valve.
- Cavity filler ball valve: It is possible that the residue that remains inside a ball valve can pose a health risk in some applications, like food production and healthcare. The fluid that goes through the pipe can also cause contamination issues. By extending the seats, a cavity filler plugs the hole, preventing these buildups.
- Trunnion ball valve: The ball is anchored to both the top and bottom of the valve. Large-scale or high-pressure applications often require this design to prevent the ball from floating off and causing problems with the seating mechanism.
Butterfly Valves
Butterfly valves are lightweight valves in one- and two-piece designs, named for their resemblance to butterfly wings. The two-piece version of these valves folds inward to allow full flow and lies flat when closed. The disk is mount on a shaft that rotates around the pipe in a one-piece design. By activating the valve, the disk is rotate to open or close, allowing gas or liquid to flow through. There are two types of butterfly valves: lug valves and wafer valves. The main difference between the two is the installation design.
- Wafer valves: Wafer valves are fairly common and are usually less expensive than lug valves. With bolts or studs and nuts, the valve is instal between two flanges. There is no way to disconnect one side of the piping with this design, but wafer butterfly valves are excellent if that is not a requirement.
- Lug valves: lug butterfly valves use threaded metal inserts in the bolt holes of the valve instead of nuts for a less permanent installation. There are two sets of bolts on each side of the flange. You can disconnect one side of the piping system and leave the other side untouched.
In terms of materials and maintenance, these valves are usually less costly. Additionally, they are lighter and faster to open and close than ball valves. Often, they are use in large-scale projects, such as municipal water systems and sewer systems. The Butterfly valves are commonly use in applications that require control of flow from a body of water. Butterfly valves are excellent for controlling flow and pressure if flow loss is not an issue. Butterfly valves have the additional benefit of being smaller than ball valves, which makes them ideal for projects that require minimum space.
How Ball Valves Differ From Butterfly Valves
Butterfly valves and ball valves accomplish similar tasks, but their similarities are somewhat limit. Both valves are:
- Rotating valves with a quarter-turn that is move 90° for opening and closing
- Great options for accurate fluid handling
- Made from durable materials, such as iron and stainless steel
- And is affordable and long-lasting
The primary difference between the valves is their effect on flow. Butterfly valves have a part of the disk that interferes with the flow, causing a drop in pressure. This, of course, is a disadvantage when consistent or high pressure is require. As a result of incoming pressure from the supply side, the valve may also be difficult to operate. To operate properly, a butterfly valve may require a bypass valve to balance out the pressure. Alternatively, the ball valve provides 100 percent flow without requiring a bypass valve. It can use in projects that require higher pressure.
Another factor to consider is the size of the application. A ball valve typically becomes less cost-effective at around 6 inches in diameter due to its design. At that point, butterfly valves are generally more economical. They are generally lighter and more affordable. As a result, they are ideal for large-scale projects where flow control is not a major concern. Additionally, butterfly valves don’t trap fluids as ball valves do, so a butterfly valve may be better for applications in food production, where residues can create health hazards.
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