Choosing the right type of butterfly valve is key to every application. The available range of butterfly valves from equipment manufacturers includes concentric, single (1x) offset, double (2x) offset, and triple (3x) offset butterfly valves. In this article, you will learn the benefits of a triple offset butterfly valve, see a sample drawing, and realize its benefits vs other types of butterfly valves.
If you are looking for more details, kindly visit discount triple offset butterfly valve.
Triple offset, as the name implies, uses three separate offsets to achieve a bubble-tight shut-off. One of the offsets applies to the location of the valve shaft relative to the centerline of the bore. Another offset is between the centerline of the disc/seat sealing surface and the shaft. Then, the third offset is the geometry of the seating surface, which creates a cone shape of the disc and seat. The combination of these three offsets gives this valve its key benefits which are as follows:
A sample drawing of a triple offset butterfly valve above clearly highlights its three offsets. The first offset (offset 1) is between the axle center of the valve stem and the valve body centerline or sealing surface. This design helps to minimize the squeezing complications between the disc and seat that are found in concentric butterfly valves. However, friction between the seat and disc remains a challenge. For this reason, the double offset design sees seldom use.
The second offset (offset 2) is between the axle center of the valve stem and the centerline of the bore/pipe. This leads to minimal friction as the valve opens and closes. In combination with the first offset, the valve’s operational life extends.
The third offset is that of the cone axis that deviates from the axle centerline and thus eliminates friction completely. Users can expect longer seat life in the triple offset butterfly valve because the sealing mechanism relies on contact pressure rather than elastic deformation of the valve seat.
This section compares the features of the triple offset butterfly valve to other types of butterfly valves.
If you want to learn more, please visit our website open valve.
The single offset butterfly valve is not common in the market because it shares a lot of similarities with the concentric/zero offset valve. Below is a table highlighting the differences between the single and triple offset valves.
FeatureSingle Offset/Concentric ValveTriple Offset ValveSeal typeThe valve seat is usually made from polymers or other soft materials to enable a friction seal with the metal disc.The three offsets allow for metal-to-metal seals using alloys for both the seat and disc.Seat frictionHigh, because friction is the basic sealing mechanism. Thus, it is susceptible to wear and results in a shorter seat lifespan.Seat friction is insignificant because sealing is by contact pressure. As a result, the valve seat enjoys much longer operational life.ANSI pressure class ratingAlthough this valve can deliver bubble-tight shut-off, its inferior sealing mechanism, and susceptibility to wear limit this to class 150.Delivers dependable sealing which does not wear easily. Models such as the Durco triple offset can achieve a 1500-pound rating.Fluid servicesBecause of its friction sealing mechanism, it is only effective with clean fluid.The triple offset sealing mechanism is more tolerable to dirt, so works with clean or dirty fluids.ApplicationsCommon in utilities and domestic applications.Can function effectively in severe service and high cyclic operations.Single Offset vs. Triple Offset Butterfly ValveThe double offset valve is an improvement of the concentric/single offset valve and provides more versatility than the single offset. Feature comparisons are noted between the double and triple below:
FeatureDouble Offset ValveTriple Offset ValveSeal type and frictionWhen compared to the single offset, the double offset greatly reduces friction. However, it still relies on plastic deformation for sealing. As a result, soft materials are still used for the valve seat.Maintains metal-to-metal seal with contact pressure.Fluid serviceSuitable for handling clean fluids only, due to friction in its sealing mechanism.Maintains effectiveness, even in dirty fluids.ApplicationsCan serve in several industrial applications including water treatment, chemicals, oil and gas, and HVAC.Also serves in industrial applications, but suits scenarios with higher operational demand.CostComes at a moderate cost i.e. more expensive than single offset valves but less than triple offset valves.The specialized machining required to achieve superior sealing makes it more expensive.Double Offset vs. Triple Offset Butterfly ValveThe butterfly valve has a very compact design belonging to the quarter family. It’s lightweight, easy to operate, and has lower torque. It’s considered a top choice for critical and severe applications. The triple offset valve design achieves zero leakage on metal-to-metal contact. The hard facing seat eliminates the rubbing between the seat and seal ring through the flow path to extend the cycle life. Its uniform sealing can operate more frequently, and open and close quickly.
Butterfly valves contain a stem that consists of three offset disks in the middle of the floor. These valves consist of a center-line with three offsets located in different positions. The balance of this valve is the stem placed behind the circular disc of this to self-adjust to the center ensuring tight sealing. Two offsets are placed from the center while the third is on the seating surface, creating a disc and seat cone shape. These valves are used where a tight shut-off, high temperatures, or zero leakage is needed. This cone angle and the two eccentric shaft offsets allow the disc to seal against the seat with no friction. They are used in applications with unique challenges such as abrasive material, high pressure or temperature, and even those prone to leaks.
These valves come in various designs and materials specific to the systems involved. They are recognized for excellent flow and control characteristics, tight sealing capabilities, and dependability across critical and severe applications. They are suited for applications requiring absolute zero leakage. Triple offset valves are hard facing, metal-to-metal valves with a longer lifespan. They are used in similar industries where a double offset valve would be used but are even more effective in demanding and tight applications such with over 900-1,500 psi or high-temperature gas or liquid.
Choosing a suitable valve is essential for the success of any flow control system. Trillium Flow Technologies™’ brand, TRICENTRIC®, delivers outstanding value in their triple offset butterfly valves. They meet stringent industry requirements and provide low cost of ownership to the end-user through improved life cycle costs, emissions control, less downtime, and low maintenance costs. You can count on Trillium Flow Technologies™ valves for complete flow control success. Our reliable legacy brands, like TRICENTRIC®, and a team of dedicated support and services experts, ensure that you have a trusted partner who adds value at every phase of your project cycle. You’ll have confidence in your flow control now and in the future.
Contact us to discuss your requirements of what is a rotary valve. Our experienced sales team can help you identify the options that best suit your needs.