Figure 1: A sectional view of a ball valve
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A ball valve is a shut-off valve that uses a rotary ball with a bore to control a liquid or gas flow. The rotary ball is rotated a quarter-turn (90°) around its axis to allow or block the flow through the valve. Ball valves are preferred for their longer service life and reliable sealing property. The wide range of operation types, connection types, circuit functions, housing materials, and other criteria make the valve selection process complex. This article guides through this process to make it easier for our readers.
Ball valves can be operated manually (Figure 2 left), electrically (Figure 2 center), or pneumatically (Figure 2 right), each with its advantages and disadvantages.
Automatic operation involves choosing between electric and pneumatic ball valves. This decision typically depends on the availability of electricity or compressed air at the installation site and the torque requirements, as pneumatic ball valves offer higher torque and are thus suitable for larger valves. Although electric ball valves have a higher initial cost, they tend to have lower operating costs than pneumatic ball valves.
Manual ball valves are ideal for situations with a low budget, absence of electricity or compressed air, or when automation is not required. However, they are not recommended if the valve needs frequent operation or if the system requires automation.
Read our electric vs pneumatic ball valve article for a more in-depth breakdown.
Figure 2: A manual ball valve (left), electric ball valve (center), and pneumatic ball valve (right).
Ball valves typically have 2-way or 3-way circuit functions:
Read our article on the circuit function of ball valves to learn more about this topic.
Figure 4: A 2-way ball valve (left) and a 3-way ball valve (right)
The flow coefficient, or Kv value, is expressed as the flow rate in m3/h of water at 20°C at a pressure drop of 1 bar. The flow coefficient can be calculated as follows:
Where:
Use our sizing calculator to find an application's Kv-value and corresponding valve size. Our valves are designated with a Kv value so customers can easily select the correct size.
The housing material of the valve should be compatible with the fluid media being used for the application. Common materials and their features are:
Plastic ball valves are lightweight, easy to install, and offer excellent corrosion resistance, making them ideal for use in corrosive environments. They are cost-effective for many applications but are generally not suitable for high-pressure or high-temperature conditions compared to metal valves.
Seal materials are crucial for ensuring leak-proof connections and maintaining system integrity in various applications. They are selected based on their compatibility with the media, temperature, and pressure conditions. While some seal materials offer excellent chemical resistance, others are better suited for high-temperature or high-pressure environments.
There are different sizes and types of ball valve connections to connect them to a system. The common ones are:
To learn more about ball valve connection types read our technical article about ball valve connection types.
Figure 3: Common ball valve connection types: threaded (top left), true union (top center), compression ring (top right), flanged (bottom left), and hose pillar (bottom right).
When selecting a ball valve, it is crucial to ensure that it can withstand the minimum and maximum pressures of your system. Both the housing and seal materials significantly influence the ball valve's pressure range. Stainless steel housings typically offer the highest pressure ratings, followed by brass and plastic materials like PVC.
However, the seal material also plays a critical role. For instance, seals made from FKM (Fluoroelastomer) provide excellent resistance to high pressures and a wide range of chemicals, making them suitable for demanding applications. Always consult the ball valve's datasheet to confirm the specific pressure range for an application.
The temperature range a ball valve can handle is determined by both the housing and seal materials. Each combination offers different capabilities:
Depending on the application, ball valves may need to be made to specific standards or receive approvals from regulatory bodies for particular applications, like drinking water or gas applications.
Residential water lines commonly have ball valves at different points. The following steps outline how to choose a ball valve for this type of application.
A ball valve selection guide helps choose the right valve based on operation type, connection type, materials, and specifications.
Measure ball valve size by determining the diameter of the pipe or opening the valve will fit, typically in inches or millimeters.
Ball valve material selection depends on fluid type, temperature, pressure, and environmental conditions to ensure durability and performance.
Choose ball valve seat material based on fluid compatibility, temperature, pressure, and wear resistance for optimal sealing and longevity.
Ball valves are a critical part of industries including oil and gas, manufacturing, chemical, and water treatment. They even have residential uses.
With so many different applications, it’s not a surprise to find many different types of ball valves. These include trunnion ball valves, welded ball valves, a metal seated ball valve, and more.
Find out more about the different types of ball valves. You’ll have the information you need to choose the best ball valve for your application.
Several types of ball valves are available, but they all have some features in common. A ball valve is a quarter-turn shut-off valve. It controls the flow of a liquid or gas.
Ball valves are well-suited for applications with high pressure, high temperatures, and high volume. They open and close quickly. They’re less prone to corrosion and damage than other types of valves.
The main parts of a ball valve are the body, the ball, the seats, and the stem.
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The valve body is the primary part of the valve. It contains all of the components to turn the valve on and off.
The ball is a rotary ball with a hole (bore) in the center. Turning the ball 90º will either let the liquid or gas flow through or stop it from flowing.
The seats are discs between the body and the ball. They support the ball and make a seal between it and the body.
The stem connects the ball to an external control mechanism like a handle or lever. Turning the stem turns the rotary ball to open and close the valve.
The different types of ball valves can be classified based on different features. These classifications are based on factors like:
The versatility of ball valves is one of their main advantages.
A ball valve can have two, three, or four ports. Most ball valves are 2-way with an input and an output.
A 3-way valve is either L-shaped or T-shaped. 3-way valves change the flow direction. They let you distribute or mix flows.
4-way valves can be L, T, or X shaped. An X (LL) port has the four ports evenly spaced around the valve chamber. It has two flow positions and a central position with all the ports closed.
The valve housing is either a one-piece, two-piece, or three-piece assembly. Threaded connections or bolts usually hold together assemblies with multiple parts.
A one-piece has the body and end connections made from a single piece of material. You can’t open it for cleaning or maintenance. One-piece assemblies are the most economical option.
You can take the two parts of a two-piece assembly apart for inspection and maintenance. You have to remove it from the pipeline to separate the parts, though.
Three-piece assemblies are the most expensive. You can work on the valve without removing it from the pipeline.
Fully welded ball valves have a body made from forged parts welded together. This design doesn’t have joints, which leaves fewer possible leak paths.
Fully welded ball valves are more compact. They’re stronger but also lighter.
Many welded ball valves use butt welds. This type of weld gives complete fusion and high strength.
You can find ball valves made from several different types of materials. The material for the valve body, ball, and seats are important to consider when choosing a ball valve.
Common materials for valve bodies include:
The choice of material depends on the conditions the valve will be operating in. Common materials for the flow control ball include stainless steel, brass, chrome-plated steel or brass, and PVC.
The valve seats can either be thermoplastic or metal.
Soft seated ball valves use a flexible thermoplastic seat material like PTFE. They provide a very tight seal. They aren’t suitable for abrasive or dirty fluids, though.
Metal seated ball valves will withstand severe service conditions. You can further harden metal seats with coatings like chromium carbide and tungsten carbide.
Ball valves use two types of designs to hold the ball in place. Most ball valves use a floating ball. Trunnion ball design is also an option.
In a floating ball valve, the ball is suspended in the liquid or gas media. Cupped valve seats support the ball. Two sealing rings hold the ball in place.
Trunnion ball valves support the ball on the top and bottom. The ball attaches to the stem on one end and a shaft (the trunnion) on the other end. The additional support reduces the load on the seat rings.
Trunnion ball valves are a good option for large diameter valves or high-pressure environments.
The hole through the ball can have several different shapes. The type of bore affects how the ball valve operates.
A full bore design has a bore diameter the same as the pipe. It reduces friction loss and is easier to clean.
A standard bore ball valve has a smaller port and ball than a full port design. Standard port ball valves restrict the flow somewhat. However, they’re less expensive.
Most ball valves have a reduced bore design. The flow area is smaller than the pipe. These types of ball valves create friction losses.
The friction loss is still small compared to other types of valves, though.
A v-shaped hole in the ball or in the shape of the seat lets you control the flow rate more precisely. The flow characteristic is almost linear. V-shaped ball valves are well-suited for applications with a high flow rate. They provide a minimal drop in pressure and a tight shutoff.
The best ball valve is the one best suited to your application. With all of the options, it can seem challenging to find the right ball valve for your project.
Whether you need trunnion ball valves, welded ball valves, or another type, Anything Flows has what you’re looking for. We offer the highest quality flow control solutions and superior customer support. You can be confident buying ball valves online from our catalog.