Over time, butterfly valves have become more and more common due to their cost-effectiveness and effective design. Butterfly valves come in a variety of designs, but the resilient-seated butterfly valve is the most fundamental type. The fluid processing sector frequently uses resilient-seated butterfly valves due to its cost-effectiveness, versatility, and ease of automation.
The seat, which forms a seal between the valve disc and the pipe flanges, is crucial to a butterfly valve's operation. The stem of this kind of valve sits in the center of the valve disc, which sits in the center of the pipe bore. These butterfly valves usually have a seat that is relatively flexible, and they depend on the disc making a lot of contact with that seat.
How many type of butterfly valve seat?
Resilient-seated butterfly valves are composed of three primary seat styles: cartridge, molded, and booted or dovetail. Every variety has unique traits as well as unique advantages and disadvantages. To correctly decide which is better for your application, let's go over the distinctions.
What is Dovetai-style type seat ?
The "dovetail" shape of the booted-style seat mates with the valve body's inner diameter. Since the fit is not physically bonded, this kind of seat is simple to remove and service. When mounted between flanges, it is prone to movement, which causes distortion that causes the disc contact points to protrude. The adaptability of booted seat butterfly valves is restricted by their sensitivity to mounting conditions. Molded and cartridge-style chairs were created to overcome the shortcomings of the booted seat.
Above photo is "dovetail” EPDM seat
What is molded-style type seat?
An injection molding procedure is used to fuse the molded-style seat to the valve body. Although the seat becomes damaged, this creates a direct link. Because the seat and valve body are combined, if the seat were to get damaged, the entire valve would need to be replaced. However, due to the permanent contact with a hard valve body, molded seats are advantageous over booted-style seats. Molded-style seats can be used for vacuum or dead end service and are resistant to distortion and displacement during valve mounting.
Above photo is molded-style seat
What is cartridge-style type?
A layer of elastomer is compression molded onto a stiff phenolic backing ring to create the cartridge-style seat, which supports the elastomer in several directions. Compared to the injection molding method used to make molded-style chairs, this compression molding method is far more reliable. It keeps tighter control over the seat dimensions and applies continuous pressure to form the shape of the seat. Cartridge seats provide the highest wear resistance and the best torque uniformity due to their tighter tolerances. By being removable, this kind of seat also outperforms the molded design. The cartridge seat could be changed instead of the valve itself in highly abrasive applications where valves must be changed often.
Above photo is cartridge-style EPDM seat
Conclusion
Cartridge seats have benefits that no other seat form can match, as the following chart illustrates. A cartridge-seated valve can perform dead end service if the valve body has an integrated retaining lip. Additionally, cartridge seats can function more effectively in a system that needs vacuum service than booted or dovetail seats. Resilient-seated butterfly valves can actually operate at their best because to the cartridge-style seat.
