Valves are an important component of any kind of piping system. They help start, stop, and regulate the flow of materials and prevent leaks and unwanted flow. Valves are vital to the operations of many machinery and equipment across various industries and applications. It is hard to imagine a set-up where valves are not involved. However, not all valves are the same.
While there are many different types of valves available in the market ball valves and gate valves are two of the most common types of valves used in almost all industries. Though both of these valves perform more or less the same function, there are structural differences between the two that make them suitable for different applications. It can be confusing to choose which one is suitable for your needs. That is where this guide can help you. Read on to find out how gate and ball valves work, what makes them different from each other, and how you can choose which one is best for your application.
What are Ball Valves?
Ball valves are ‘shut-off valves’ in that they help prevent the flow of materials through the piping system. They are called ball valves because of their structure and function; each valve features a small sphere or ball inside. The ball has a hole in its center called a bore, it is the position of this bore that indicates whether a ball valve is open or closed.
Ball valves are normally controlled by a lever. This lever can rotate 90 degrees, when it is rotated perpendicular to the pipe, the ball valve is opened. The bore of the valve aligns with the pipe and allows materials to flow through. Rotate the lever again bringing it parallel to the pipe to stop the flow. The bore of the valve now becomes perpendicular to the pipe and stops any flow.
Ball valves have a simple design and are easy to turn on and off quickly. They are durable, rarely freeze, provide reliable service, and can be used across multiple industries and applications. They are mostly used in oil and gas applications, marine applications, pharmaceuticals, and more. Ball valves are compact in size and require very little space to install.
What are Gate Valves?
Gate valves get their name because they feature a flat closure element that moves up and down to start or stop the flow of materials. This closure element, also called a gate, is connected to the stem of the valve. The stem is in turn connected to the actuator, which in case of manual gate valves, is a handwheel. When you rotate the handwheel, the gate slides up, removing any barrier for the materials in the pipe and they are free to flow. Rotating the handwheel counter clockwise, slides the gate back in place, stopping the flow of materials.
Gate valves are sturdy and durable. They are used in on/off applications where the valve is used infrequently. You can find gate valves in the oil and gas industry, pharmaceuticals, manufacturing, automobile industry, and marine applications. Gate valves prevent pressure drop due to flow of materials. That is why they are great for high pressure and high temperature applications as well.
Gate valves come in many different shapes and sizes. They are extremely versatile both in terms of design and application. They are bi-directional which means you can use them to regulate flow of materials in any direction. They also require very little maintenance and can last for ages.
What are the Differences Between Ball Valves and Gate Valves?
Now that you know what ball and gate valves are and how they work, let’s take a look at what makes them different from each other. As both valves perform basically the same function, it can be confusing to choose which one is right for your needs. Here are some main differences between ball valves and gate valves.
Structure
Ball and gate valves may work in similar ways, but they have different structures. While ball valves feature a small sphere attached to a stem, gate valves have a round or rectangular gate that is attached to the stem and is used to regulate the flow of materials. Because of the way they are structured, ball valves offer immediate shut-off, which is not possible for a gate valve to do.
Gate valves don’t provide quick shut-off, but they do give you more finely tuned control over the flow of materials and the pressure of the flow. For example, gate valves are great in situations where there’s high water pressure potential. In similar situations, a ball valve would likely form a water hammer, while a gate valve makes sure that doesn’t happen.
Ball valves may in smaller is size than gate valves, but they require more space for actuation. Manually operated ball valves require their lever to be turned at 90 degrees to work. The lever requires more space to work. While a manual gate valve is operated through a handwheel. So even if the gate valve is larger in size, it may take less space than a ball valve to operate.
Another structural consideration is that gate valves are more prone to corrosion than ball valves. The valve opens and closes with a screw handle attached to the gate. The handle is in constant contact with the material flowing through the valve and can easily corrode. This hampers the performance of the valve. You can choose a material like stainless steel and brass for handle construction to counter this problem.
Ports
The inlets and outlets of a valve are called ports. Gate valves are bi-directional, this means they have only two ports. The ports can be threaded, soldered, or flanged depending upon the type of gate valve and the application.
Ball valves on the other hand, can have two or more ports. These ports may be threaded, soldered, or flanged based on the valve’s application and type. Ball valves with three ports are used for mixing and diverting the flow of materials. In addition to their number, the size and function of ports in valves also plays a role. A full-port ball valves features a ball with a bore size that is the same as the diameter of the pipeline the valve is attached to. A reduced-port ball valve features a ball that has a smaller bore size than that of the pipeline.
Flow Characteristics
Gate valves can function in either fully open or fully closed states. If a gate valve is partially open, it causes throttling which can damage the valve and affect its function. Also, a partially opened gate valve is not proportional to the motion of the closure element. This means you cannot use gate valves for active control of media flows. Gate valves are more suitable for shutoff of materials flowing in linear direction. They are used in piping situations where flow needs to be regulated infrequently like when isolating equipment or sections of pipes.
Ball valves are designed so that the flow of materials is closely proportional to the rotation of the closure element or ball. This causes a flow characteristic called the ‘modified equal percentage’. Ball valves are thus suitable for active control of media flows. Ball valves seal very well, better than gate valves in most instances. That is why they are great for regulating the flow of gasses and other light materials that are prone to leakages. Ball valves have a quick shut-off so they are mostly used in applications where you need to start or stop the flow completely and frequently.
Actuation
Gate valves are usually used for isolation of general purpose flows and for high-pressure and high temperature applications that require manual operation. This is the reason why most gate valves are actuated using a handwheel. The handwheel offers more control over opening and closing the valve. However, it is more difficult to operate as it requires great strength especially during high-pressure operations. Also, since handwheels need to be rotated for the valve to turn on or off, it is difficult to actually ‘see’ whether the valve is open or closed. This problem is eliminated when using mechanical, electric, or pneumatic gate valves.
Ball valves are used for active control of material flow so they can be manually, electrically, or pneumatically actuated. Manual ball valves are more frequently used in industries as they are cheaper and they offer greater control over the flow of materials. Another advantage of manual ball valves is that the lever needs to be held perpendicular to the pipeline for the valve to be opened and turned back when closed. This makes it easy to ‘see’ just from the position of the lever whether the valve is open or closed.
Cost
Comparing the cost of gate and ball valves is like comparing apples and oranges, since both of them are used for different purposes and applications. However, if all things are kept the same, ball valves are generally more expensive than gate valves. This is because they offer more features and are more versatile than gate valves. Also, ball valves are more durable than gate valves as they are less prone to corrosion. So the slight increase in price more than makes up for the years of use you’ll get out of ball valves.
How to Choose the Right Valve for Your Application?
Choosing between a ball valve and gate valve comes down to a number of factors. Here are some considerations you need to make to see which valve is better for your application:
The type of medium that you need to control can dictate the type of valve you need. Gate valves are better with liquids and viscous liquids like oils as they are more prone to leakages than ball valves. Knife gate valves can help you regulate the flow of slurry materials. Ball valves can be used with liquids and gasses as they provide a firmer seal.
The size of the space you have can also help you decide between a ball and gate valve. Ball valves are smaller is size but manually actuated ball valves need more space. Gate valves are normally larger in size.
The kind of application you require is also important when choosing a valve. Gate valves are more suitable for high-pressure, high-temperature, infrequent applications. Whereas, ball valves are more suitable for active control of media flow.
The cost of valves is another consideration. Ball valves are generally more expensive than gate valves but they offer a more reliable operation as well.
Conclusion
Both ball and gate valves are used frequently in many different kinds of industries and across different applications. Choosing the right valve for your needs can be easy when you break down the operation you need the valve to perform. No matter which valve you choose, make sure to buy from a trusted valve manufacturer and get valves that have proper warranties. At SIO we offer a great deal of attention to design, manufacture, pack, and deliver valves that are of the highest quality. We use state-of-the-art testing equipment and software to make sure our valves are safe to use and provide reliable operation for years.
Learn more about our products here. Browse through our catalogue to find the best gate valves and ball valves for your needs.
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