Sep. 01, 2025
A double offset butterfly valve has two special offsets in its design. The shaft is behind and not on the centerline of the disc. This lets the disc move in a cam-like way. The movement stops the seal from being pressed until the disc shuts. This helps lower friction and wear. Double offset butterfly valves make a tight and strong seal. They last longer than regular butterfly valves. Many industries use this valve because it works well and lasts a long time. It can also handle many types of fluids.
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A double offset butterfly valve has a special design with two offsets. The first offset moves the stem away from the disc’s centerline. The second offset moves the stem away from the valve body’s centerline. This changes how the disc and stem sit inside the valve. The disc does not stay in the middle. It sits a bit to the side. The stem also sits away from the valve body’s centerline.
This double offset structure makes it different from single offset and zero offset designs. In a single offset butterfly valve, only the stem moves away from the disc’s centerline. The double offset design does more. It lets the disc move away from the seat quickly when the valve opens. This quick movement helps stop scraping and wear on the seat. The valve can handle higher pressures and temperatures. It works well with metal seats and in tough places.
Note: The double offset structure helps the butterfly valve last longer and work better in hard jobs.
The double offset butterfly valve makes a camming action when it works. When the valve opens, the disc lifts away from the seat in a smooth way. This happens because of the two offsets in the design. The camming action means the disc only touches the seat at the start and end of turning. Most of the time, the disc does not rub the seat. This lowers friction and wear.
The camming action also means you need less force to use the valve. People can open and close the butterfly valve with less effort. The seat and disc last longer because they do not scrape much. The valve makes a tight seal when closed. The disc presses against the seat only at the end of closing. This stops leaks and keeps the seal tight.
The conic sealing profile in the double offset butterfly valve is important too. The disc and seat meet at a small angle, not flat. This shape helps the disc slide into place with less friction. The contact area stays small, so the valve can seal tightly without much force. The conic profile lets the butterfly valve handle higher pressures and temperatures. It also helps the valve work well with many fluids, even those that are rough or can cause damage.
A double offset butterfly valve is known for tight sealing, long life, and handling tough jobs. The special structure and camming action make it a top pick for many industries that need strong and safe shutoff.
A double offset butterfly valve opens and closes in a special way. The stem is not in the middle of the disc or the valve body. This design lets the disc move in a cam-like path. When you turn the handle or actuator, the disc lifts off the seat right away. The disc does not drag along the seat as it opens. It moves out fast and smooth.
This camming action is important. In a regular butterfly valve, the disc touches the seat most of the time. That causes more friction and wears out the parts faster. In a double offset butterfly valve, the disc only touches the seat at the start and end. Most of the time, the disc does not rub the seat.
Tip: The camming action helps the valve last longer and keeps the seal tight.
The sealing method is called positional sealing. The disc presses on the seat only when fully closed. This squeeze makes a tight seal and stops leaks. The valve must close in the right spot to work well. This design is good for jobs where the valve opens and closes a lot and handles many fluids.
The double offset design helps lower seat wear and the force needed to use the valve. The disc moves away from the seat quickly, so there is less friction. The seat and disc do not scrape much during opening and closing. This means the seat lasts longer and does not need to be changed often.
The table below shows how double offset butterfly valves compare to other types:
A double offset butterfly valve needs less force than a zero offset valve. The cam action means friction only happens at the start and end. This makes it easier to open and close, even by hand. Smaller actuators can be used, which saves space and money.
The butterfly valve works well with soft seat materials. These seats can handle medium temperatures and pressures. The valve gives good sealing, lasts a long time, and is easy to use. Many industries pick the double offset butterfly valve for these reasons.
Note: Less friction means less wear and lower force, so the valve works well for a long time.
If you want to know how double offset butterfly valves work, look at the camming action and how the disc moves away from the seat. This design keeps the valve strong, simple to use, and reliable for many jobs.
Zero offset butterfly valves have a simple design. The stem and disc sit in the middle. This type works well for basic liquids and gases. It can handle heat up to 400°F. It also works with pressure up to 250 PSI. The sealing is not very strong. So, it fits jobs with lower pressure and heat. The seat covers the valve body. This keeps the media from touching the body.
Double offset butterfly valves use two offsets. These make a cam action that lowers friction and wear. The valve can handle more pressure and heat. Adjustable packing on the stem helps stop leaks and lower emissions. Many industries use this valve for tough jobs. These include oil and gas, power plants, and chemical factories. The sealing is much stronger and lasts longer than zero offset butterfly valves.
Key differences in sealing effectiveness:
- Zero offset butterfly valves have a concentric design. They work best for low-pressure jobs.
- Double offset butterfly valves use a cam action. This gives better sealing and makes them last longer.
- Double offset valves fit high-pressure and high-temperature needs.
Double offset butterfly valves use soft seats. These seats seal by changing shape a little. Some friction and wear happen when the valve works. So, you need to do maintenance. The seat lasts a medium amount of time. Soft materials wear out after a while. The valve needs more force to work because of friction.
Triple offset butterfly valves add a third offset. This makes a cone-shaped sealing surface and a true metal-to-metal seal. The disc does not rub the seat. So, friction and wear are very low. The valve has no spaces for dirt to collect. This means less maintenance. The seat lasts longer. The valve needs less force to work. Automation is easier, and you do not need to service it often.
Triple offset butterfly valves last longer and need less maintenance than double offset butterfly valves. The metal-to-metal seal and no rubbing make them good for hard jobs.
Double offset butterfly valves work well in tough jobs. Their special design lets the disc move away from the seat fast. This lowers friction and wear. The valve closes tightly every time. Many industries use these valves for a bubble tight seal. They work even when pressure is high. The disc only touches the seat at the end of closing. This keeps the seal tight and strong. These valves help stop leaks. Operators trust them for safe use and tight sealing.
Double offset butterfly valves are picked for important systems because they shut off tightly and seal well.
Double offset butterfly valves can handle many pressures and temperatures. The table below shows common ratings for these valves:
Some double offset butterfly valves work in very cold or hot places. They can handle temperatures from -29°C up to 900°F. This depends on the seat and body materials. The wide range lets the valve work in many places. It fits cold water and hot, rough jobs. The valve keeps a tight seal in all these conditions. This is a big advantage.
Double offset butterfly valves last a long time and need little care. The design lowers friction, so the seat and disc wear less. Many valves use stainless steel or special alloys. These metals do not rust in harsh places. The valve works well for water treatment, oil and gas, and power plants.
Most double offset butterfly valves need care only once a year. Some last up to 30 years if cared for well. The simple design means fewer parts to change and lower costs. Triple offset valves may last longer in very hard jobs. But double offset butterfly valves are still strong and easy to care for in most industries.
Double offset butterfly valves are used in many industries. They seal tightly and work well. Oil and gas plants use these valves for controlling hydrocarbons. These fluids can be under high pressure and heat. Water treatment plants use them to control flow. They also help stop contamination in water systems. Chemical plants like these valves because they resist corrosion. They also stop leaks when handling strong chemicals. HVAC systems use double offset butterfly valves. They help control air flow and keep the temperature steady.
Chemical and power plants use these valves for tough fluids and gases. The valves keep a tight seal, even in hard jobs. This helps stop leaks and keeps things safe. The valves respond quickly and are built strong. They help control steam and cooling water in power plants. The double offset shape lowers friction and wear. This makes the valves last longer and need less fixing. Operators can pick different materials for the valves. Stainless steel and special alloys work for rough or corrosive fluids. These features make double offset butterfly valves a good choice for many jobs.
Double offset butterfly valves help water plants meet green goals. Their design lowers friction and wear. This means less fixing and less energy use. The tight seal stops leaks. This helps keep water clean and cuts down on waste.
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Picking the right double offset butterfly valve is important. You need to think about a few things. Industry rules say to follow these steps:
Flow rate is very important when picking a valve size. The valve must let enough fluid through without causing problems. The double offset butterfly valve design helps control flow well. It also keeps pressure drops low. This makes it a good fit for many industrial systems.
Double offset butterfly valves are special because of their smart design. They seal well and are simple to take care of. The table below shows their top benefits:
When picking a valve, people should look at pressure, temperature, and what fluid is used. Checking the valve often and picking the right materials helps it last a long time.
A double offset butterfly valve has two special offsets in its design. These offsets let the disc move away from the seat fast. This helps lower friction and wear. Because of this, the valve lasts longer than a regular butterfly valve.
Yes, double offset butterfly valves can work in hot places. Many are made with strong materials like stainless steel. Some valves can handle heat up to 900°F. The seat and body materials decide how much heat the valve can take.
Industries use double offset butterfly valves in many places. Oil and gas plants use them to control flow. Water treatment plants use them to stop leaks. Chemical plants and HVAC systems also use these valves. They work with many fluids and help keep systems safe.
Most double offset butterfly valves need to be checked once a year. The design helps lower friction and wear. This means the seat and disc last longer. Regular checks help the valve work well for a long time.
If you’re in the water industry, you may not have heard about double eccentric butterfly valves, or a double offset, they are the same thing. So what exactly are they, and how do they work?
In this blog, we’ll delve into the ins and outs of double eccentric butterfly valves and explore the vast advantages that they offer.
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A double offset butterfly valve, we call it our DEX valve, is a high-performance butterfly valve designed to resolve many of the common complaints about standard/concentric butterfly valves.
It’s called “double eccentric” because the valve body seat is offset to the front side of the body, and the disc is offset to the front side of the shaft.
Here are some of the most common complaints about AWWA standard C504 butterfly valves:
Many butterfly valves leak because when they are in the open position, the disc pinches the rubber seat causing a seatset or leak path. This creates a visible divot in the rubber seat, which allows water to leak by when they are closed.
The inside of the body shaft area of most butterfly valves are not coated. They are raw iron in this area. If they were coated, the coating would wear as the valve is opened and closed causing the disc to flutter, and destroying the valve.
Many butterfly valve manufacturers use plastic sleeves or packing glands to wrap the shafts, which allow water into the uncoated area of the shaft body.
To resolve this problem, many manufacturers require an exercise program to break up the rust caused by a faulty design.
Double eccentric butterfly valves offer several benefits, including:
Because the double eccentric butterfly valve features a double offset design, the disc and seat do not touch when the valve is in the open position. This eliminates the risk of creating a seatset, or leak path, which is the number one complaint with butterfly valves.
Properly designed and manufactured double eccentric butterfly valves, utilize bronze bushings and O-ring seals to prevent water from entering the valve shaft area. This design eliminates the corrosion caused by plastic sleeves and packing glands. Since there is no need to break up corrosion and rust caused by a poor design, you can leave the valves in the open position until you need to close them.
Double eccentric butterfly valves are known for their versatility. They are an excellent choice when critical service valves are needed. In other words, if you need a valve that will isolate the media and not leak these are the valves for the application. They can be used for pump control, air valve isolation, reservoir intake isolation, transmission lines, PRV isolation, and general isolation around the plant or in the distribution system. They are designed for use in clean water, industrial, and gas applications.
Double eccentric butterfly valves are known for their low maintenance requirements. These valves are designed to last and are easy to repair if needed, reducing the overall cost of ownership.
It’s important to choose a valve capable of handling tricky applications and meets all the requirements for your project. If you’re looking for a reliable and effective valve, consider the DEX Double Eccentric Butterfly Valves.
The following are its top four features:
DEX Double Eccentric Butterfly Valves are designed to be leak-free. They even come with a unique warranty that offers a leak-free guarantee for a minimum of three years. *Guarantees up to ten years are available depending on the application and requirements of the project.
Unlike standard butterfly valves that use plastic sleeves or packing glands creating a wetted shaft in an uncoated area, the DEX Double Eccentric Butterfly Valves have a dry shaft with eight
O-ring seals. This prevents corrosion and ensures that the valve does not need to be exercised regularly, as is required for standard butterfly valves.
At Av-Tek, our DEX Double Eccentric Butterfly Valves are easy to maintain in all sizes from 6” to 120”. The first scheduled maintenance is at 20-25 years, and repair kits are reasonably priced and simple to install.
Av-Tek strives to always have industry leading lead times. We know the demands of the industry and do our best to help you avoid downtime. The smaller sizes, from 6” to 42”, are almost always In-Stock and ready to ship. Larger sizes, and large projects, are available quickly to help keep even the most complex projects moving forward without delays.
When choosing a valve for your system, it’s essential to consider your system’s specific needs. Selecting the right valve can help reduce disruptions and maintain smooth operations for your system.
Moreover, you can count on DEX Double Eccentric Butterfly Valves as a reliable choice for your various applications. They help to maintain optimal operations while maximizing long-term cost savings.
For more information, please visit Cast Steel Globe Valve-DIN.
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