The invention of the butterfly valve enabled the advancement of processes and applications in a variety of sectors. This basic guide will explain what a butterfly valve is, how it operates, and the various design variations.
What is a Butterfly Valve?
A butterfly valve is a mechanism that regulates the flow of materials inside large pipe sizes by rotating a disc quarter-turn.
A rod runs through the center of a disc and is attached to an actuator that regulates the disc’s motion. The disc is either parallel or perpendicular to the medium flow. A butterfly valve differs from conventional valves in that the disc is always in the flow, creating a pressure change regardless of the valve’s position.
Valve reliability is essential in sound systems. Our butterfly control valve range includes disc valves that are precisely sized for various purposes and manufactured in compliance with industry standards. Browse our product page to find the best butterfly valve for your individual application. Refer to our request a quotation page for bespoke parts.
Why is it known as a Butterfly Valve?
Some valves are named after their shape, for example, ball valves, globe valves, needle valves, and so on. Other valves are named after their movement and function, such as a gate valve, a plug valve, a pinch valve, a life valve, a slide valve, and so on. The movement of a butterfly control valve is also called after it.
The butterfly valve derives its name from the way it moves, which is comparable to a wing in flight. The rod resembles the body of a butterfly, while the disc moves like a butterfly wing. The action of a butterfly valve is similar to that of a butterfly that has landed, with the wings moving up and down in a 90-degree motion.
What Is the Purpose of a Butterfly Valve?
A butterfly valve controls the flow of media by beginning, slowing, or stopping it. The disk rotates 90 degrees to open and close and is suitable for any compatible application. The butterfly valve is frequently selected over other types of valves because it is less expensive and lighter in weight.
Extreme temperatures and corrosion are elements that can readily undermine a valve’s seal in specific procedures. The butterfly valve can tolerate extreme cold or heat. This means that the seal retains its integrity, which is crucial in high-stakes applications like energy production and petroleum processing (a single leak might endanger public safety or the environment).
A butterfly valve is a type of quarter-turn valve. It functions similarly to a ball valve in terms of quick shutoff, but unlike a ball valve, it can also open and close progressively. This distinction means that the disc is constantly present in the flow and allows for a pressure drop.
This disc is installed in the pipe’s center. A rod inserted through the disc and an actuator situated outside the valve regulate disc movement. Turning the actuator either perpendicular or parallel to the flow positions the disc.
Where can I find the Butterfly Valve?
There are some general recommendations for orienting butterfly valve pieces. The butterfly valve requires some separation from other components like pumps, elbows, and other valves – 6 pipe diameter separation is optimum.
The butterfly valve is often installed with the valve stem vertically and the actuator directly above it, however in other circumstances, the stem is installed horizontally. When linked to a pump or check valve, the disc must have enough space to avoid interfering with other parts.
There are three major types of butterfly valves.
While these valves all perform fundamentally the same function, butterfly valve designs vary to accommodate varied actions. The three primary types of butterfly valves are listed below.
Butterfly Valve with Zero Offset
The zero-offset design is sometimes known as a “concentric” or “rubber seated” design. The term “zero-offset” refers to the absence of offset caused by the valve stem. Interference along the disc edge at the stem between the disc and the rubber seat shuts the valve.
The rubber-seated valve has the lowest pressure rating (up to 250 PSI) and may resist temperatures as high as 400°F. Its rubber seat encases the body, preventing contact with the substance and preserving the media’s purity.
Butterfly Valve with High Performance Double Offset
This butterfly valve is known as a double offset because the offset occurs twice: once at the line of the disc seat/body seal and once at the bore. Off-center location improves seal durability. High-performance valves can withstand pressures of up to 1440 PSI and temperatures of up to 1200°F.
A cam-action occurs when the stem is behind the disc and rubs against it during rotation at 90° for the first 10 degrees of opening and shutting.
Butterfly Valve with Triple Offset
The triple offset butterfly valve is the ideal form of butterfly valve for high-pressure systems. The triple offset is the most advanced of the three, with fewer emissions and is designed to work in a variety of situations. It can sustain 1,480 PSI of pressure and has a heat tolerance of 1200°F.
The triple offset valve, like the double offset valve, has two offsets in the center, but a third offset has cam action with right-angled conical sealing. Because the metal seal components do not make touch until they reach their final point, it is frictionless and long-lasting.
The Most Common Butterfly Valve Applications
Some operations necessitate more tolerant and wear-resistant valves with unique characteristics. Some frequent applications that rely on the specific processes of a butterfly control valve are listed below.
The attributes required to manage fluid flow in any piping system include simple design, high durability, and low maintenance. A White seat is ideal for the Food Processing sector because it is certified food grade.
While ordinary robust seated valves are not 3A authorized, many on the market retain sanitary connections both inside and outside. The valve body material might vary from epoxy coated iron to nylon 11 coated iron to bronze, 304SS, and 316SS.
In refineries, the butterfly valve is often used. These would normally employ a “high-end” High-Performance valve with Steel Bodies, or a Triple Offset design that is “Fire Safe” and bubble tight. The resiliently seated variant is used in many water-related applications.
Shut Off Valves
Above 1.5″-148″, a butterfly valve is frequently the best choice for a general shut-off valve. Because of their basic design, they take up less space and weigh less than other types of valves. These valves often produce a tighter seal than a gate or globe valve and are bubble tight. This is very important when attempting to halt fluid flow since it prevents any fluid from going through the pipe when closed.
Butterfly valves are often utilized in ships that use ABS-approved materials due to their great saltwater endurance. This type of valve successfully establishes a water-tight shutdown in a ship’s plumbing system, preventing any flow through the pipe. Because of their modest size, they may also be employed in the ship’s cramped quarters.
They can be used for “jack up” rigs, ballast systems, ship side, and a variety of other purposes. Many applications also require Fire Safe approved valves. Automation and pneumatic function (“closed-loop” pneumatic underwater, electric, and hydraulic) are also available.
Use valves that have an ISO-5211 mounting pad and stem. This makes it easier to find a replacement at any port. Also, be aware of valves with only an ISO-5211 mounting pad because the stems are frequently manufacturer’s “special.”