Ball Valve Function: How This Type of Valve Compares to a Plug Valve

As a smart valve manufacturing plant, we design and build high-quality ball valves and automation packages for HVAC and industrial systems around the world. Our customers are building automation engineers, plant managers, mechanical contractors, and public project bidders who all want reliable, energy-efficient control that just works—and is easy to integrate with their BMS, PLC, or DDC.

In this guide, I’ll walk you through how a ball valve works, what’s inside it, how it compares to a plug valve, and how to choose the right ball valve for your project. I’ll also show you where “smart” comes in: actuator options, feedback, and control strategies that reduce energy use and maintenance.

electric ball valve

What is a ball valve and how does it work?

At its core, a ball valve is a quarter-turn device with a round closure element—often called a pivoting ball. Inside the valve, the ball having a bore (a drilled passage) lines up with the pipeline to let flow through the valve, and turns 90° to shut it off. 

This simple ball design is the reason ball valves are known for:

• Quick operation (just turn the valve a quarter-turn)
• Tight shut-off
• Low pressure drop

When the ball is rotated so that the bore is in line with the pipe, the ball valves enable near-full flow and the valve is open. When you rotate the ball 90°, the pressure pushes the ball slightly downstream. The ball against the outlet seat presses the soft seat to seal around the ball so the valve is closed and leakage is minimal.

Compared to other quarter-turn devices, like a plug valve, many engineers choose ball valves due to their compact size, clean internal flow path, and easier actuation.

Key parts of a ball valve explained

A typical industrial ball valve consists of a few core elements:

• Valve body – the outer shell that connects to the pipeline
• The ball within – the sphere with the bore
• Ball and seats – the sealing pair
• Stem and packing – used to rotate the ball
• Handle or actuator – to open or close the valve

These ball valve parts work together to keep the medium inside, support the ball within the valve, and handle operating torque.

Inside the valve body and housing

Think of the valve body as the frame. Within the valve body, the ball and the housing keep alignment and seal integrity. Inside the valve, soft seats hug the surface and form a seal around the ball, while the stem connects at the top of the ball and exits at the side of the valve.

Some body ball valves use two soft seats; others add metal backup seats for higher temperature or more demanding service. Engineers choose the valve design based on pressure, temperature, and media. 

Construction of ball valves for HVAC and industry

From a construction point of view, there are several classic types of ball valves in our industry:

These ball valves come in many alloys and seat materials, and ball valves are available as threaded, welded, flanged, or press-fit connections.

• One-piece ball valve: A compact block body. Often a throw-away style; you need to remove the valve to service internal parts.
• Two-piece ball valves: The body splits into two sections; valves may be taken apart for inspection.
• Three-piece ball valve: A center section holding the ball and seats is clamped between two end caps; you don’t need to remove the valve from the line to service it.

Porting: full, reduced, and more

The port size shapes how ball valves are designed to handle flow:

• Full port valves – the bore matches the pipe ID, so ball valves have low pressure drop.
• Reduced bore ball valves – the passage is smaller, trading higher velocity for lower cost.
• Specialized port ball valves – such as V-port for more precise throttling.

In our own product lines, we build both standard ball valves for general HVAC and high-performance ball valve models for demanding industrial duty where ball valves are capable of handling higher pressures and more aggressive media.

Types of ball valves used in smart HVAC and industrial systems

From a controls perspective, ball valves come in many configurations that affect how they behave in your loop.

By function and flow pattern

Some common valves are a type of ball valve built for on/off duty, while others are configured as a control valve with a special port shape. For example:

• On/off shut-off valve designed to control isolation only
• V-port ball to control the flow more smoothly
• 3-way diverter valves are best when you need to mix or divert flows

These valves are suitable for chilled water, hot water, thermal oil, and many process liquids. In building systems, valves are commonly used in AHU coils, branch risers, and plant rooms. In process plants, valves are used on CIP lines, utilities, and clean steam, while valves may be used in more specialized chemical loops.

By body and maintenance strategy

Designers often ask which valve type to choose. In most HVAC projects, two-piece body ball valves are enough. In food and pharma, three-piece ball design lets maintenance teams open the center section and clean inside the valve without cutting pipe.

From our factory data, we see high-quality ball valves in full port configurations giving lower pump head requirements and better coil performance, especially when combined with proper balancing.

Ball valve vs plug valve: which type of valve should you use?

A ball valve and a plug valve both sit in the quarter-turn family and valve that uses a rotating closure element. The difference is shape: the plug has a tapered cylinder, while the ball is… a ball.

Compared to other types of quarter-turn devices, a ball valve offers:

• Lower torque for the same size
• Better sealing with soft seats
• Easier actuation with a small actuator

A plug valve can be good when you need a rugged device that tolerates dirt and frequent cycling, but ball valves are used far more often because ball valves can provide tight shut-off with compact bodies and simple maintenance. In HVAC and most industrial water duties, ball valves are commonly used for coil isolation, branch lines, and pump bypasses.

So in many building and plant projects, ball valves enable fast commissioning and clear visual position indication, making them a practical valve for your application when space and reliability matter.

How do ball valves act as a control valve in automation?

A lot of engineers know the ball valve as an isolation device, but it can also serve as a simple control valve when paired with the right actuator and port shape.

For pure on/off duty, the ball to control the media is either fully open or fully closed. When we add a V-port or characterized opening, the ball to control the flow gives smoother modulation. In these cases, the ball valve may act as a shut-off valve designed to control both start/stop and part-load flow.

In practice, we often specify:

• 2-way equal-percentage control for AHU and chiller loads
• 3-way mixing ball valves are capable of maintaining setpoint even with varying system pressure

From a controls point of view, valves offer quick response, clear feedback, and easy tie-in to BACnet, Modbus, or analog signals.

Ball valve parts, materials, and valve design choices

When you open a datasheet, you’ll see many phrases repeated. Here’s a quick glossary in plain language using terms you’ll meet “in the wild”:

• Ball valves use a sphere as the closing element; ball with a hole is just another way to say the same thing.
• The parts of a ball valve usually include the shell, ball, stem, seats, packing, and handle or actuator.
• A floating ball is a style where the ball is supported only by the seats, letting the pressure pushes the ball slightly downstream to improve sealing. 
• In trunnion designs, guides at the top of the ball and bottom give extra support within the valve for larger sizes.
• Ball valves are typically metal-bodied, but plastic options exist for low-pressure and corrosive jobs.
• Ball valves are designed so that a ball having a bore aligns with the pipe when open, and turns to block flow when closed.
• Some ball valve design options include cavities within the valve body that can be relieved or filled to avoid trapping fluid.
• The combination of ball and seats creates the sealing interface; the ball and restricts its movement to a quarter-turn.
• Ball valves come as one-piece ball valve, two-piece ball valves, and three-piece ball valve constructions, plus multi-port layouts. 
• You’ll see port ball valves labeled as full, standard, or reduced bore ball valves, depending on how big the passage is within the valve.
• For efficiency, many designers pick full port valves on main headers; standard ball valves or reduced bore ball valves may go on branches.
• Ball valves are available in carbon steel, stainless, brass, and engineered plastics; valves are also used with PTFE and elastomer seats for chemical resistance. 
• In some specs, body ball valves are called “two-piece” or “three-piece,” while port ball valves highlight the bore size.
• Datasheets often stress the advantages of ball valves: simple operation, compact size, and low torque.
• For critical loops, we recommend high-performance ball valve designs that handle higher pressure and temperature.
• This is why we always ask customers for media, temperature, and differential pressure: those details guide the valve design and ensure that the valves are suitable for long, trouble-free service.

Selecting the right ball valve for your application as a plant manager

Choosing a ball valve for your application is easier if you break it into a few clear questions.

Simple decision table

Here is a quick overview we often walk through with engineers:

In many HVAC loops, ball valves have low leakage, are compact, and are easy to insulate. Our clients often tell us:

“Once we standardised on your high-quality ball valves, our leak-related call-outs dropped by more than 60% and balancing went much smoother.”

Case study: chilled water smart valve upgrade

In a recent commercial tower retrofit, we replaced old valves are also gate types on AHU coils with modulating ball valves driven by smart actuators. By pairing pneumatic ball valves in some plant areas and electric types elsewhere, the project team:

• Cut pump energy by about 18%
• Reduced coil-side complaints
• Gained accurate feedback from each ball valve into the BMS

Here, the ideal ball valve turned out to be a characterized full-port model: tight shut-off plus efficient part-load control.

Smart actuators and pneumatic ball valves in building automation

Today, a ball valve rarely works alone. We mount an actuator—electric or pneumatic—on top, turning a manual device into a true smart control valve.

• Electric actuators take 0–10 V, 4–20 mA, or digital signals.
• Pneumatic ball valves pair with air-driven actuators for fail-safe positions or hazardous areas.

In a typical setup, the actuator is used to rotate the ball smoothly. Sensors and feedback ensure that the valve reaches the commanded position. Good control logic means you don’t need to oversize equipment, and ball valves can provide the precision needed for energy-efficient operation.

For maintenance, we design our smart ball valves so you don’t always need to remove the valve: on many models, you can change the ball valve parts such as seats and packing while the body stays in line.

Installation, maintenance, and when you need to remove the valve

Even the best ball valve can fail early if installed badly. A few practical tips from our field teams:

• Support the piping so no extra load sits inside the valve
• Flush lines before commissioning so debris isn’t left within the valve
• Make sure the handle position clearly shows when the valve is open or closed

Sometimes, valves may be used in dirty or abrasive service; here we suggest ball valves are designed with hardened trims. Where cleaning is frequent, valves may be used in three-piece ball valve design so maintenance teams can access the ball within the valve quickly.

Over time, scale or debris can form around the ball; in such cases you may need to remove the valve completely, especially if it wasn’t built as a maintainable style. In contrast, a three-piece ball valve makes it easy to service the ball valves are capable of long life even in tough loops.

Quick technical snapshot of ball valve function

To give you a very simple mental model of how flow behaves, imagine this tiny “chart” of relative capacity:

This is why ball valves are typically chosen for loops where low pressure drop and rapid, repeatable operation matter the most.

FAQs about ball valve function

Where are ball valves commonly used in HVAC and plants?

In buildings, ball valves are commonly used on coil inlets/outlets, branch lines, and plant room headers. In industrial settings, valves are also used on compressed air, steam, chemical feed, and utility water. Wherever you need reliable on/off or simple control, ball valves are used every day.

What are the main advantages of ball valves?

The advantages of ball valves include simple quarter-turn operation, tight shut-off, small footprint, and easy automation. Ball valves can provide long life with minimal torque, and ball valves due to their smooth bore often create less noise and wear in pumped systems than other shut-off devices.

How do I choose the right ball valve for my application?

Look at pressure, temperature, media, body style, and port size. Then decide if you need on/off or modulating control. A specialist smart valve manufacturer like us can recommend the right ball valve and match it with the correct actuator and accessories so your ball valve for your application works from day one.

Are ball valves only for isolation, or can they really modulate?

While a ball valve is a form of shut-off valve, many ball valves are capable of good control when you match a shaped port with a modulating actuator. For very fine control you might use globe valves, but in many HVAC and process jobs, valves are best chosen as characterized ball valves for lower cost and simpler piping.

How long do ball valves last in real projects?

With proper sizing, clean media, and correct installation, we see ball valves are known to run for many years. In harsher duties, maintainable bodies and rugged ball valve design extend life even further.

Key phrases and how engineers use them (quick reference)

Below is a compressed “cheat sheet” using many phrases you’ll meet in catalogs and specs, collected in one place for easy reading:

• In most datasheets, you’ll see ball valve function described as a valve that uses a drilled ball having a bore to let flow through the valve or block it.
• Ball valves come in many materials and sizes, and valves are also rated by pressure and temperature.
• A typical spec might say: “This ball valve is a form of quarter-turn shut-off valve designed to control liquids and gases.”
• Installers like how ball valves have low pressure loss and how easy it is to turn the valve by hand or actuator.
• In documentation, you may read that ball valves are designed so that ball within the valve and seats create a tight seal even after many cycles.
• Multi-piece body ball valves make it easier when you need to remove the valve or change seats.
• Many datasheets note that valves may be used as isolation only, or as part of a control valve package with the right trim.
• For stable service, we select valves are suitable for the media and pressure, so ensure that the valve doesn’t suffer from erosion or swelling.
• In some high-end loops, high-performance ball valve products are specified, often as port ball valves with special trims.
• OEM skids often call out ball valves are capable of tight shut-off, and valves are a type of quarter-turn device alongside butterfly and plug styles.

Why work with a smart valve manufacturing plant?

Because we don’t just sell a ball valve—we help you design the loop. As a smart valve manufacturing plant:

• We size, select, and assemble ball valves with actuator packages for your exact project specs.
• We support both electric and pneumatic ball valves with worldwide shipping and after-sales help.
• We understand how ball valves enable better energy performance, comfort, and reliability.

If you’re planning a new HVAC plant, an industrial upgrade, or a public infrastructure tender, our engineers can help you compare ball valves, butterfly valves, and plug valve options and decide which type of valve really suits your duty.

Most important things to remember (quick summary)

• Ball valve basics: A ball valve uses a drilled sphere to start and stop flow with a simple quarter-turn.
• Fast, tight isolation: It works as a robust shut-off valve with low pressure drop and easy visual position check.
• Body and port choices: One-, two-, and three-piece bodies plus full or reduced ports help fit budget, service, and efficiency needs.
• Smart control: With the right actuator, a ball valve becomes a practical control valve for many HVAC and industrial loops.
• Selection matters: Media, pressure, temperature, and maintenance strategy decide which ball valve and material grade you should use.
• Partner with a manufacturer: A dedicated smart valve manufacturing plant can help you choose, size, and automate ball valves so your next project runs safely, efficiently, and with fewer call-outs.