How to Distinguish Between a Trunnion Ball Valve and a Floating Ball Valve: A Customer’s Guide

How to Distinguish Between a Trunnion Ball Valve and a Floating Ball Valve: A Customer’s Guide

Choosing the right ball valve for your application can be tricky. Among the different types, trunnion ball valves and floating ball valves are two common options. While both serve the same primary function—controlling the flow of liquids or gases through a pipeline—they differ significantly in design, performance, and suitability for various operational conditions. Understanding these differences can help you make a more informed decision based on your specific needs. Let’s explore how to distinguish between these two types of ball valves.

1. Understanding the Basics: What is a Ball Valve?

Before diving into the specifics of trunnion vs floating ball valves, let’s review what a ball valve does. At its core, a ball valve consists of a spherical ball with a hole through the middle. When the ball rotates, the hole aligns with the pipeline, allowing fluid to flow. Turning the ball 90 degrees blocks the flow, creating a shut-off valve. This simplicity, reliability, and ease of use have made ball valves a popular choice across a wide range of industries, from oil and gas to food processing and water treatment.

2. Trunnion Ball Valve: Design and Function

Trunnion ball valves are engineered with additional support at both the top and bottom of the ball, known as the “trunnion.” This support mechanism prevents the ball from floating freely within the valve body. As a result, the ball remains fixed in position, and the flow of fluid is controlled by rotating the ball 90 degrees.

The trunnion design offers several key benefits:

• Reduced Seat Wear: Since the ball doesn’t move freely, the sealing surfaces are less prone to wear. This makes trunnion ball valves ideal for high-pressure and high-flow applications where consistent sealing is crucial.
• Better Control: Trunnion-mounted ball valves typically provide better control of the flow rate in large pipelines. The fixed ball allows for precise regulation of fluid movement, even in challenging conditions.
• Heavy Duty Applications: These valves are often used in industries like oil and gas, power plants, and large-scale water systems, where the demands on the valve are more extreme.

3. Floating Ball Valve: Design and Function

In contrast, floating ball valves use a ball that is not fixed in place. Instead, the ball “floats” within the valve body, held in place only by the pressure of the incoming fluid. When pressure is applied, the ball moves slightly toward the valve seat, creating a seal. When the valve is closed, the ball is pushed against the seats at both ends of the valve.

Key characteristics of floating ball valves include:

• Simplicity: Floating ball valves have a simpler design than trunnion valves. They consist of fewer parts and require less maintenance.
• Versatility: These valves are commonly used in smaller pipeline systems and applications where fluid pressures are moderate. They work well in industries such as water treatment, HVAC, and food processing.
• Lower Cost: Due to the simpler design, floating ball valves are generally more affordable than trunnion ball valves, making them a cost-effective option for smaller or less demanding applications.

4. Key Differences Between Trunnion and Floating Ball Valves

Design & Construction

• Trunnion Ball Valve: Features a fixed ball supported at both ends by trunnions. This design allows the valve to handle higher pressures and larger flow rates without causing excessive wear.
• Floating Ball Valve: The ball “floats” within the valve body, only sealed against the valve seats by the pressure of the flow. This design is generally more compact and simple.

Sealing Performance

• Trunnion Ball Valve: Offers superior sealing because the ball is fixed in place, reducing the risk of excessive wear and leakage, especially under high-pressure conditions.
• Floating Ball Valve: The ball seals against the seats under pressure, which means that sealing efficiency can decrease in high-pressure environments.

Pressure Handling

• Trunnion Ball Valve: These valves are better suited for high-pressure applications (up to 10,000 psi or more). The trunnion support ensures that the valve can handle larger volumes of fluid without causing damage.
• Floating Ball Valve: Floating ball valves are generally designed for lower to moderate pressure applications (typically up to 1,500 psi). They can handle a reasonable amount of pressure but may struggle in extreme conditions.

Size & Application

• Trunnion Ball Valve: Ideal for larger diameter pipelines and high-flow applications. Due to their design, they can handle larger volumes of fluid and maintain consistent performance in industrial settings.
• Floating Ball Valve: Common in smaller pipelines and less demanding applications. These valves are widely used in residential, commercial, and light industrial applications.

Cost

• Trunnion Ball Valve: Typically more expensive due to their robust construction and suitability for heavy-duty operations.
• Floating Ball Valve: More affordable, making them a popular choice for applications where cost is a significant concern.

5. Which Ball Valve Should You Choose?

Your decision between a trunnion and a floating ball valve will depend on the nature of your application. Here are a few factors to consider:

• Pressure & Flow Requirements: If your system requires high pressure and large volumes of fluid, a trunnion ball valve may be your best option. Their robust construction and superior sealing performance ensure long-lasting operation in demanding conditions.
• Cost Considerations: For less critical applications or smaller systems, floating ball valves provide an affordable yet reliable solution. Their simpler design makes them an economical choice for many industries.
• Valve Size: Larger pipelines with high flow rates generally benefit from trunnion ball valves. For smaller systems, a floating ball valve may be sufficient and more practical.
• Maintenance Needs: Trunnion ball valves typically have a longer lifespan due to their design, though they may require more complex maintenance. Floating ball valves, with their simpler design, are easier to maintain but may wear faster under extreme conditions.

6. Conclusion

Distinguishing between a trunnion ball valve and a floating ball valve ultimately comes down to the specific demands of your system. Trunnion ball valves excel in high-pressure, high-flow, and heavy-duty applications, offering superior control and durability. On the other hand, floating ball valves are perfect for smaller, lower-pressure systems that require a cost-effective solution without compromising basic functionality.

Understanding the nuances of these two ball valve types can help you make an informed decision based on your unique operational requirements. Always consider the size of your system, pressure conditions, and long-term maintenance when choosing the right valve for the job. By selecting the correct ball valve, you ensure efficiency, reliability, and cost-effectiveness in your fluid control systems.