Butterfly valves are similar to ball valves in terms of operation. They are quarter-turn valves for stopping, regulating, starting, and throttling flow. In general, you can use butterfly valves for large volumes of fluid.

There are different butterfly valves, each of which is designated for a specific set of applications. For example, when we talk about their offset designs, you'll understand that each offset type is suitable for a different pressure setting. While you can use a triple offset high-performance butterfly valve for slight vacuum pressure to high-pressure applications, a zero offset valve is suitable for the lowest pressure applications.

Butterfly valves used to be used in different places than today

Butterfly valves used to be used for low-pressure applications that did not require tight shutoff. In the past, these valves also did not require flow control. They were favored because they were lightweight and space-saving, and systems could benefit from their low-pressure drop.

As efforts have been made to improve the operation of butterfly valves, valve designers have incorporated many features to expand their capabilities.

Today, valves with multiple offset flaps and improved body materials are available. Modern butterfly valves have resilient seats, double and triple eccentric flaps, and O-rings for the flaps. With these valve design innovations, you can easily use butterfly valves for tight shutoff, high-pressure and high-temperature applications, and throttling.

What's more, the new emergence of valve features can accommodate large volumes of gases and slurries. You can even choose from various valve sizes, from small valves to large valves, to meet your application needs.

What are the primary uses of butterfly valves?

You can use any size valve for on/off service or start/stop flow control in this application. In addition, the operation requires a low-pressure drop during the open position.

This application requires more attention to which type of valve and size to use as a regulating control valve. You should also identify the medium, the fluid type, the operation and installation method, and the pressure drop. The valve designer or engineer can determine some of this information for calculations.

Regulating Fluid Flow

Butterfly valves are widely used to regulate fluids. As a regulating valve, this is accomplished by the action of an actuator connected to the valve's stem and plate assembly. The degree of angular opening translates into the exact amount of fluid passing through the valve. Thus, the flow of the system is controlled by the actuator.

The actuator can be manual or automatic. To remotely control a regulating valve, it must have a flow controller. This controller will automatically translate the information into a valve mechanism to open or close based on the system's flow rate.

Automatic actuators can be operated remotely by a pneumatic system, a hydraulic piston, or an electric motor. A handwheel can perform the manual operation in a gear system attached above the valve that connects the valve to the spindle.

Flow Isolation

Butterfly valves can be used for flow isolation due to their lightweight, easy operation, and quarter-turn action.

However, when you use a butterfly valve as an isolation valve, you need to ensure it does not negatively impact your system performance.

For example, we want the fluid to flow smoothly to the pump impeller in a pumping system. This is to avoid system losses and cavitation. To do this, vortex formation should be eliminated or reduced. One of the reasons for vortex formation is that the valve impedes the flow. It can occur in butterfly valves due to the interruption of the flow of water in the butterfly valve.

This is why care should be taken when using this type of valve as an isolation valve. System losses should be considered in the calculations to maintain good system performance.

Backflow prevention

Some food manufacturing processes require aggressive flushing procedures where butterfly valves can be used to prevent backflow. Since food processing plants should be clean and operate under extremely sanitary conditions, backflow must be prevented.

As a throttle valve

Butterfly valves are commonly used to regulate large flow rates of fluids, including viscous slurries, but it should be noted that they are not a good choice for precision throttling.

However, recent developments have enabled butterfly valve manufacturers to offer valves that can throttle flow very precisely.

For throttling service, you can find high-performance butterfly valves. They are manufactured using higher industry standards and are suitable for large high-pressure and high-temperature applications. Typically, these types of valves are made to handle large volumes and many types of media, including viscous oils and seawater.

For constant load applications

Butterfly valves can handle large volumes of fluid but are sensitive to changes in load in the system. This type of valve is limited in its ability to handle small load variations. Allowing a few millimeters of opening equates to a large volume difference.

However, the design can be enhanced to diversify its control range, especially in large applications where pressure is precisely regulated.

For space-constrained applications

One of the best features of butterfly valves is that they are economical and space-saving. Space-constrained systems can benefit from butterfly valves compared to ball valves.

In facilities where space is limited, it can be difficult to install an effective piping system. Filters, valves, and other equipment can take up a tremendous amount of space. Thankfully, butterfly valves are the only globe valves that don't require much more space. You can install them in tight spaces, unlike other bulkier valves.

For liquids and gases

Butterfly valves can usually handle liquids and gases, even slurries, but not bulk solids. This is because dry bulk solids are abrasive and will corrode the materials (and seals) of the butterfly valve. In addition, a butterfly valve is inefficient at conveying solids because its valve flaps restrict the flow of solids.

Where can I find butterfly valves?

Lightweight butterfly valves are primarily used in water supply lines and potable water control services. Other lightweight valves, such as PVC butterfly valves, can be used in aquariums and sprinkler systems. Some general-purpose butterfly valves are also used for fuel flow control.

For large, heavy-duty, and high-pressure applications, such as the oil and gas industry, high-quality and high-performance butterfly valves are used. These premium valves are certified, and quality tested to meet quality requirements and international standards.

Below, you can see some of the industries that use butterfly valves for industrial processes:

HVAC

Vacuum services

Aerospace

Refrigeration and air conditioning systems

Irrigation and agricultural needs

Corrosion treatment

Lubrication

District heating, mining, and shipbuilding yards

Oil industry

Wastewater treatment

Slurry applications

High pressure and high-temperature water and steam services

Compressed air applications

Sanitary valve applications

Sprinkler systems

Gas applications

The butterfly valve is used in applications that require handling large volumes. It can be used for flow control and regulation as well as on/off service. Recent developments have allowed this type of valve to throttle flow more accurately and perform well in high-temperature and high-pressure applications. Although butterfly valves can be used as isolation valves, the piping system should be carefully designed to eliminate system losses.

Butterfly valves regulate flow by starting, slowing, or stopping the media. The discs are open and close with a low 90-degree torque rotation for any compatible application. Because they are less costly and lighter, butterfly valves are often preferred over other types of valves.

For some processes, extreme temperatures and corrosion are factors that can easily affect valve sealing. Butterfly valves can withstand extreme cold or extreme heat. This means that the seal maintains its integrity, which is critical for high-risk applications such as energy production and oil processing (where a single leak could threaten public safety or the environment).

Principle of operation

The butterfly valve is classified as an angle-stroke valve. It works similarly to a ball valve used for a quick closing, but unlike a ball valve, a butterfly valve can also be opened and closed gradually. This difference means that the disc is always present in the flow and allows the pressure to drop.

The disc is mounted in the center of the pipe. The movement of the valve disc is controlled by a rod inserted into the disc and an actuator located outside the valve. Turning the actuator positions the disc to be perpendicular or parallel to the flow. 

Where is the butterfly valve located?

There are some standard guidelines for butterfly valve part orientation. Butterfly valves need to be located a certain distance from other components such as pumps, elbows, and other valves - 6 pipe diameter separation is ideal.

Typically, butterfly valves are installed with the stem mounted vertically and the actuator directly above it, but in some cases, the stem is mounted horizontally. When connected to a pump or check valve, the disc must have clearance so as not to interfere with other components nearby.

3 Main Butterfly Valve Types 

While the function of these valves is essentially the same, there are several variations of butterfly valve designs to accommodate different operations. The following are the three main types of butterfly valves.

Zero Eccentricity Butterfly Valves

 "Concentric" or "rubber-seated" are other names for zero offset designs. Zero offset means that there is no offset in the valve stem. The valve is sealed by a flap edge interference at the stem between the valve flap and the rubber seat.

The rubber-seated valve has a minimum pressure rating (up to 250 PSI) and can withstand heat up to 400°F. Its rubber seat encases the body to prevent contact with materials that maintain media purity.

High-Performance Double-Eccentric Butterfly Valve

This butterfly valve is called double offset because the offset is located in two positions: at the valve seat/body seal line and at the bore. The eccentric positioning increases the durability of the seal. High-performance valves can withstand pressures up to 1440 PSI and temperatures up to 1200°F. 

Cam action occurs on the stem behind the valve flap as it opens at 10 degrees before 90° friction during rotation but is also used to close at 10 degrees.

Triple Eccentric Butterfly Valves

The best type of butterfly valve for high-pressure systems is the triple eccentric butterfly valve. Of these three types, the triple offset is the most advanced, has lower emissions, and is designed for use in a variety of environments. It is heat resistant to 1200°F because it can withstand pressures up to 1,480 PSI.

Like the double offset valve, the triple offset valve consists of two centrally located eccentric valves, but the third eccentric valve has a cam action with a right-angle tapered seal. Since the metal sealing parts do not touch until the last point, they are frictionless and wear-resistant.

Common butterfly valve applications

Some processes require more forgiving and wear-resistant valves with special features. Here are some common applications that rely on the unique mechanisms of butterfly control valves.

Food processing 

Simple design, high durability, and low maintenance are the characteristics needed to regulate fluid flow in any piping system. Certified food-grade seats are best suited for the food processing industry, so white seats are preferred. 

While standard resilient seat valves are not 3A certified, there are many on the market that maintain internal and external sanitary connections. Valve body materials range from epoxy-coated iron to nylon 11-coated iron to bronze, 304SS, and 316SS.

Refineries

Butterfly valves are commonly found in oil refineries. These typically use more "high-end" high-performance valves with steel bodies or "fireproof" and gas-tight triple eccentric designs. Many applications involving water use resilient seat versions.

Closing Valves

Butterfly valves are often the best choice for general-purpose globe valves from 1.5"-148". Their simple design allows them to take up less space and weigh less than other types of valves. These valves provide a tighter seal than globe gates and are often gas-tight. This is most useful when trying to stop the flow of fluids, as it prevents any fluid from passing through the pipe when it is closed.

Shipbuilding

Because of their high durability in saltwater, butterfly valves are often used on ships that have chosen ABS-approved materials. This type of valve effectively creates a watertight shutoff in the ship's piping system to prevent any flow in the piping. Their small size also allows them to be used in the tight spaces commonly found on ships. 

They can be used on "jack-up" rigs, ballast systems, ship's sides, and many other applications. Many applications also require fire-safe certified valves. Additional features are automation and pneumatic functions ("closed-loop" pneumatic subsea, electric and hydraulic).

What is a butterfly valve?

A butterfly valve is a mechanism that regulates the flow of material in a large pipe diameter by rotating a disc a quarter turn. 

A rod passes through the center of the disc, and the rod is connected to an actuator that controls the movement of the disc. The disc is positioned parallel or perpendicular to the media flow. Butterfly valves differ from other valves in that the valve flap is always inflow, resulting in pressure changes at any position of the valve.

Sound systems depend on reliable valves. Our butterfly control valve selection consists of disc valves that are sized to fit a variety of applications and are manufactured to strict industry standards. Browse our product pages to find the best butterfly valve for your specific operation. For custom parts, see our Request a Quote page.

Why are butterfly valves called butterfly valves?

Some valves are named after their shapes, such as ball valves, globe valves, and needle valves. Other valves are named for their motion and function - gate valves, plug valves, pinch valves, life valves, slide valves, etc. Butterfly control valves are also named for the motion they make.

Butterfly valves get their name from the fact that their motion is similar to a flying wing. The stem resembles the body of a butterfly, while the disc moves like a butterfly wing. The motion of a butterfly valve is similar to that of a butterfly whose wings move up and down 90 degrees when landing.