Comparison of Butterfly Valves – Concentric butterfly valves, Double-offset butterfly valves, and Triple-offset butterfly valves

 The butterfly valve is a quarter-turn valve that can be used as an on-off valve or throttling valve. There are two types of butterfly valve, a concentric and an eccentric type. The eccentric type can be single, double, or triple-offset type. Even though it is possible to have a single-offset butterfly valve, but it is rarely found in the market. The most available in the market for an eccentric type are double-offset or triple-offset. Some times this 2 sub-type of butterfly valve is also called as a high-performance butterfly valve. With these 3 variants of a butterfly valve (concentric, double offset, and triple offset), in what condition we should use a concentric, double-offset, or the triple-offset one? First of all, let’s see what is the difference between concentric, double-offset, and the triple-offset butterfly valve.


Concentric Butterfly Valves

The concentric butterfly valve is a standard or a general use butterfly valve. The shaft is located in the center of the disc. During opening or closing, there are some parts of the disc that always in-contact or rubbing the seat. This arrangement will make the seat experience friction each time the valve is operating. In a typical application, this concentric butterfly valve is limited to class 150 due to its seat design.



Double-offset Butterfly Valves also called High Performance Butterfly Valve

The double-offset butterfly valve is a valve that has 2 offset compare with the concentric butterfly valve. The first offset is the shaft located not in the center of the disk but located on slightly behind the disc. This offset will make the valve has a continuous sealing surface on the disc.


The second offset is the shaft located not in the pipe center-line but located on slightly in the right side of the center. This offset will make the valve didn’t touch the seat at all when it is fully opens (see illustration above). This arrangement will make the seat experience less friction than the concentric type butterfly valve and thus will prolong its lifetime. In a typical application, this double-offset butterfly valve is limited to class 600 only.


Triple-offset Butterfly Valves

The triple offset butterfly valve is a valve that has 3 offset compare with the concentric butterfly valve. Just like the double-offset butterfly valve that has 2 offsets, this triple offset also has the same offset except it has one additional offset which is a conical shape seat. This conical-shaped seat will match with the disc that also fabricated to match the seat. This arrangement will make the seat has no friction or rubbing while closing or opening. This arrangement will also make the valve has a bubble-tight in the high-pressure application and much longer lifetime rather than a double-offset butterfly valve. In typical application just like the double-offset butterfly valve, this triple-offset butterfly valve is limited to class 600 only.


Difference between Concentric, Double-offset, and Triple-offset Butterfly Valve



FEIDA is specialized in High Performance Butterfly Valve for more than 15 years. There are 2 main facilities includes 2 valve assembly & testing factories, 1 large CNC machinery plant, 1 investment casting foundry (3000T/Y) and 1 valve R&D center, equipped with most advanced production equipment and testing equipment.


FEIDA VALVE is the top ranking China double offset butterfly valve manufacture. The annual output of high performance butterfly valve is more than 100,000,000 set.


The fire safe butterfly valve is also in FEIDA VALVE product range. Our fire safe butterfly valve is certificated by American Petroleum Institute (API) according to API 607 standards.


FEIDA also build up a dustless workshop to produce ultra-clean valve for some critical working condition such as nuclear industry, semiconductor industry etc.


In the dustless workshp, FEIDA also produce the food-grade valves. FEIDA food-grade valve is certificated by Food and Drug Administration United States (FDA).


If you are interested in valves, you can contact us directly, email:

ethan@feidavalve.com


评论

发表评论

此博客中的热门博文

The bonds between PSA(Pressure Swing Adsorption) and High Performance Butterfly Valve

图片
  High performance butterfly valves ： Generally refers to  double eccentric butterfly valve  and  triple eccentric butterfly valve ,due to their excellent working performance and high sealing ability (compared with concentric butterfly valve) are widely used in petrochemical,power plants,metallurgy,civil heating fields.Eccentric butterfly valves have the good working performacne to meeting sever and strict requirements in many different industries.Today, we are going to introduce the application of eccentric butterfly valve in air separation for making oxygen,hydrogen,CO etc. At present,the mature air separation system is PSA(Pressure Swing Adsorption),it need certain number of programmed valves (valve parts usually double or triple eccentric butterfly valve) in its pipeline system to control and adjust the medium. FEIDA  double (and tripple) eccentric butterfly valve are widely used in this kind of PSA system due to the valves' excellent features: 1-Long service life,on-off 1 mill
阅读全文

Hardening method of metal hard sealed ball valve balls and valve seats

  At present, the commonly used hardening processes for the surface of  metal hard sealed ball valves  mainly include the following: (1) Surface welding (or spray welding) of hard alloy on the sphere can achieve a hardness of over 40HRC. The process of surface welding of hard alloy on the sphere is complex, with low production efficiency, and large area welding can easily cause deformation of the parts. Currently, there is relatively little use of surface hardening technology on the sphere. (2) The surface of the sphere is plated with hard chromium, with a hardness of 60-65HRC and a thickness of 0.07-0.10ram. The chromium plating layer has high hardness, wear resistance, corrosion resistance, and can maintain surface brightness for a long time. The process is relatively simple and the cost is relatively low. However, the hardness of the hard chromium coating will rapidly decrease as the temperature increases due to the release of internal stress, and its working temperature cannot exce
阅读全文

Introduction to the Function, Principle, and Characteristics of Globe Valves

  Globe valves   are used to cut off the flow of media, and are suitable for situations that require frequent opening. The sealing parts of a globe valve are the valve disc and valve seat. In order to ensure a tight closing of the globe valve, the mating surface of the valve disc and valve seat should be ground or a gasket should be used. The sealing surface can also be embedded with corrosion-resistant and wear-resistant materials such as bronze and stainless steel.The valve disc and valve stem of the globe valve are connected in a movable manner to ensure a tight fit between the valve disc and valve stem. The lifting and lowering of the valve disc of a globe valve is generally controlled by the valve stem. The upper part of the valve stem is a handwheel, and the middle part is a threaded and packing sealing section. The function of the packing is to prevent the internal medium of the valve body from leaking along the valve stem. The function of a shut-off valve 1、 The main function o
阅读全文