A: Ball valves are mainly used in midstream. They’re actually used for their rotational motion that uses the ball as a disc to stop or start fluid movement.
A ball valve is a 1/4 shut-off valve that can control transfer flow using a rotary sphere with a centered bore. It is in the open position when the bore is aligned parallel to the direction of flow allowing the substance to pass thru. In the closed position, the bore is perpendicular to the flow blocking anything from passing.
Ball valves are used quite often both in the residential and commercial market due to their reliable sealing ability and long lifespan. They can be used in everything from hoses to water heaters, to fuel trucks.
Parts Breakdown Of Ball Valves
Ball valves have a simple construction that is made up of five main components:
Valve Stem
This is a rotary shaft that connects the ball inside to the lever that controls the rotation of the ball.
O-Ring
This creates a seal between the stem and the valve housing. Usually, nitrile rubber is the most common material the O-ring is made of.
Valve Housing
The valve housing is the encasement, if you will, that holds all the other components in position. It also provides for inlets and outlet connections. Valve housing for ball valves comes in one, two, or three-piece construction:
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- One-piece: By far, the most inexpensive choice to go with. In this iteration, the two components that encase the ball are welded together. This can be a disadvantage as it means you cannot do any maintenance on it. Usually, this style is used in lighter applications.
- Two-piece: In two-piece ball valves the body has threaded connection points. So, they can indeed be taken down for maintenance. However, the valve has to be completely removed from the pipe to do this.
- Three-piece: The parts in a three-piece valve are held together with a bolt. You don’t need to remove the valve all the way to perform maintenance on it. This is the most expensive style but is best for sanitary applications such as food service.
Rotary Ball
The ball with the bore that is situated within the valve can also come in different styles. Typically, they are made from PVC, stainless steel, and some are even chrome-plated brass or steel. The ball can be either floating or trunnion-based depending on the application. The bore design also plays a big factor in the operation of each design.
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- Floating Ball Design: The valve seats give the ball support to accommodate a wide array of temperature applications. Currently, this is the most popular ball design based on usage.
- Trunnion Ball Design: In this design, the ball gets support from both the bottom and the top. This reduces the load on the valve seats and is mainly used in high-quality valves for reliable sealing.
- Reduced Bore: Most ball valves use this bore design, the bore size of the valves is less than the diameter of the inlet or outlet. This creates a bit of friction loss in the system but in the overall picture, it’s negligible.
- Full Bore: This simply means the bore size is equal to the diameter of the pipe. This results in no friction loss but it costs more and is rarely needed for most applications. However, they are easier to clean, but a less-expensive standard bore is usually a sufficient option.
- V-Shaped Bore: This is exactly as it sounds—the bore is V-shaped. This allows for a more precise rate of flow when rotating the ball.
Valve Seats
Seats are the seal that sits between the ball and the valve housing. Most ball valves use Teflon for valve seats—however, some use other synthetic materials or even different metals.
How Do Ball Valves Work?
As we covered earlier, ball valves employ a rotary ball with a bored out center to control the flow. The ball is controlled by a stem that has a lever attached to it. The opening and closing of the valve can be done manually with the level, or it can be automated. Automatic ball valves open and close on their own using electricity or a pneumatic actuator.
For the flow to pass through, the bore needs to be lined up with the direction of flow. This is visually evident when the level is parallel to the pipe. If you want to stop the flow the bore needs to be perpendicular to the flow direction. In this case, the lever is also perpendicular to the pipe.
Most ball valves consist of at least two ports; however, some have three or even four ports. There can be a significant risk of water hammer when using manually operated valves. This is mainly with fast-flowing substances such as water, or other low-viscosity media. Three port valves contain a T or L-shaped bore which aids in distribution or mixing substances.
Ball valves are incredibly versatile and can be deployed in many different types of industrial applications. They endure high pressure and temperatures, yet they still offer a long service life and at lower costs than other valve styles.
However, ball valves are not used for precision applications such as usage as a control valve. This is because while they are great at controlling flow, the control is less precise. They are mainly for applications where basic flow control is needed but not precise accuracy.
Methods Of Actuation
Ball valves can be actuated either manually, with electricity, or pneumatically. In an electric setup, an electric motor rotates the ball when needed. This is a decent option for reducing the possibility of water hammer.
Pneumatic ball valves use compressed air to turn the valve. They are usually used with much larger valves for efficiency.
Things You Should Consider When Choosing Design
Ball valves are offered in a wide range of designs, temperature/pressure ratings, and materials. Therefore, you must make careful considerations when choosing the right ball valve for your application.
- Port: Unless your application requires it, a basic two-port setup will suffice.
- Actuation method: You will have to determine the efficiency level needed for your application and whether remote operation is needed. If neither is a factor, manual actuation is appropriate.
- Bore size: Consider the diameter needed for your flow. Most ball valves go with a reduced bore, but trunnion variations can support diameters greater than 100mm.
- Materials: The materials used will depend on the media being pushed through the pipe. For example, brass is suitable for water, gas, air, and oil. However, it is not suitable for corrosive media. You would need to use stainless steel or PVC depending on the type of corrosive it is.
- Pressure: The valve you choose needs to be able to withstand the maximum pressure level you will be working with. High-performance ball valves are specifically designed for high-pressure, industrial applications that support roughly up to 14,500 psi.
- Temperature: You can get a ball valve that can withstand temperatures up to roughly 400°C.
Applications
Ball valves are used in so many applications but most commonly they are found in potable water and gas applications.
- Water: The ball valves in water applications are mainly used for regulating pressure and flow.
- Gas: Ball valves are also used for gas in both gaseous and liquified gas products such as propane for residential and commercial use.
Where To Buy Ball Valves?
TPC Industrial is your top source online for ball valves for any application. In addition to ball valves, we also carry a wide range of PVF supplies. Contact us today and let us help your project be a success.
