Choosing a ball valve seems easy until you see all the options. Pick the wrong one, and you could face restricted flow, poor control, or even system failure.

The four main types of ball valves are categorized by their function and design: the floating ball valve, the trunnion-mounted ball valve, the full-port valve, and the reduced-port valve. Each is suited for different pressures and flow requirements.

I often talk with Budi, a purchasing manager for one of our partners in Indonesia, about training his sales team. One of the biggest hurdles for new salespeople is the sheer variety of valves. They understand the basic on/off function, but then they get hit with terms like “trunnion^[1],” “L-port,” or “floating^[2].” A customer might ask for a valve for a high-pressure line, and the new salesperson might offer a standard floating valve when a trunnion valve is what’s really needed. Breaking down these categories into simple, understandable concepts is key. It’s not just about selling a product; it’s about providing the right solution so the customer’s project succeeds.

What are the four types of ball valves?

You need a valve, but the catalog shows multiple types. Using the wrong one can create a bottleneck in your system or mean you’re overpaying for features you don’t even need.

Ball valves are often classified by their ball design and bore size. The four common types are: floating and trunnion-mounted (by ball support) and full-port and reduced-port (by opening size). Each offers a different balance of performance and cost.

Let’s break these down simply. The first two types are about how the ball is supported inside the valve. A floating ball valve^[3] is the most common type; the ball is held in place by the downstream and upstream seats. It’s great for most standard applications. A trunnion-mounted valve^[4] has extra mechanical supports—a stem at the top and a trunnion at the bottom—holding the ball. This makes it ideal for high-pressure or very large valves. The next two types are about the size of the hole through the ball. A full-port (or full-bore) valve has a hole the same size as the pipe, causing no flow restriction. A reduced-port valve has a smaller hole. This is perfectly fine for many situations and makes the valve smaller and more affordable.

Comparing the Four Main Types

How do you know if a ball valve is open or closed?

You’re about to cut into a pipe, but are you sure the valve is closed? A simple mistake here can lead to a huge mess, water damage, or even injury.

You can tell if a ball valve is open or closed by looking at the handle’s position relative to the pipe. If the handle is parallel to the pipe, the valve is open. If the handle is perpendicular (forming a “T” shape), the valve is closed.

This is the most basic and crucial piece of knowledge for anyone working with ball valves. The handle’s position is a direct visual indicator of the ball’s position. This simple design feature is one of the main reasons ball valves are so popular. There is no guessing. I once heard a story from Budi about a junior maintenance worker at a facility who was in a hurry. He glanced at a valve and thought it was off, but it was an older gate valve that required multiple turns, and he couldn’t tell its state visually. He made the cut and flooded the room. With a ball valve, that mistake is almost impossible to make. The quarter-turn action and the clear handle position provide instant, unambiguous feedback: in line is “on,” across is “off.” This simple feature is a powerful safety tool.

What is the difference between T type and L type ball valves?

You need to divert flow, not just stop it. Ordering a standard valve won’t work, and ordering the wrong multi-port valve can send water to the completely wrong place.

T-type and L-type refer to the shape of the bore in the ball of a 3-way valve. An L-type can divert flow from one inlet to one of two outlets. A T-type can do the same, plus it can connect all three ports together.

This is a common point of confusion for people buying their first 3-way valve. Let’s think about a valve with three ports: bottom, left, and right. An L-Port^[5] valve has a 90-degree bend drilled through the ball. In one position, it connects the bottom port to the left port. With a quarter turn, it connects the bottom port to the right port. It can never connect all three. It’s perfect for diverting flow from a single source to two different destinations. A T-Port^[6] valve has a “T” shape drilled through the ball. It has more options. It can connect the bottom to the left, the bottom to the right, or it can connect the left to the right (bypassing the bottom). Crucially, it also has a position that connects all three ports at once, allowing for mixing or diverting. Budi’s team always asks the customer: “Do you need to mix flows, or just switch between them?” The answer immediately tells them if a T-Port or L-Port is needed.

L-Port vs. T-Port Capabilities

What is the difference between a trunnion and a floating ball valve?

Your system operates under high pressure. If you choose a standard ball valve, the pressure can make it difficult to turn or even cause the seals to fail over time.

In a floating valve, the ball “floats” between the seats, pushed by pressure. In a trunnion valve, the ball is mechanically anchored by a top and bottom shaft (the trunnion), which absorbs the pressure and reduces stress on the seats.

The difference is all about managing force. In a standard floating ball valve^[7], when the valve is closed, the upstream pressure pushes the ball hard against the downstream seat. This force creates the seal. While effective, this also creates a lot of friction, which can make the valve hard to turn, especially in large sizes or under high pressure. A trunnion-mounted valve^[8] solves this problem. The ball is fixed in place by the trunnion supports, so it doesn’t get pushed by the flow. The pressure instead pushes the spring-loaded seats against the stationary ball. This design absorbs the immense force, resulting in much lower torque (it’s easier to turn) and longer seat life. This is why for high-pressure industrial applications, especially in the oil and gas industry, trunnion valves are the required standard. For most PVC systems, the pressures are low enough that a floating valve works perfectly.

Floating vs. Trunnion Head-to-Head

Conclusion

The four main valve types—floating, trunnion, full-port, and reduced-port—offer options for any application. Knowing the difference between them, and specialized types like L-port and T-port, ensures you choose perfectly.