There’s a lot that goes into choosing the right butterfly valve for your application. Different butterfly valves are built to withstand different temperatures and pressure levels, so it’s important you know the ins and outs of your application to find one that suits your needs. Once you know the temperatures you need your butterfly valve to endure and other properties of the fluids or gases the butterfly valve will make contact with, you can decide whether you require a general service or high-performance butterfly valve. In this post, we’ll compare and contrast the two types and look at the applications for which each is better suited.
Why Butterfly Valves?
Butterfly valves halt the flow of liquid or gas through a piping system. A metal disc inside the valve’s body is positioned so it can stop materials moving through the pipes when closed. Users can open or close the valve by turning it. Since butterfly valves are quarter-turn valves, they open and close whenever the operator turns 90 degrees. They can be operated via handles, gears or automatic actuators, depending on the application.
Butterfly valves can be used for an extensive number of applications, from amusement park rides to power plants. They’re space-efficient and cost-effective compared to other valve types.
General Service Butterfly Valves
This type of butterfly valve is the all-around standard for general processing applications. You can use them for applications involving air, steam, water and other chemically inactive fluids or gases. General service butterfly valves open and close with a 10-position handle. You can also automate their opening and closing using an air or electric actuator for automatic on/off, throttling and isolation control.
The valve’s seat covers the body to ensure that the materials being processed don’t make contact with the body. This seat design is ideal for operating in vacuum applications. The valve’s shaft runs through the disc and is attached to the disc via tight spline, with 3 bushings top and bottom that act as the shaft bearing.
One of the benefits of general service butterfly valves is that their design is simpler, allowing them to be custom-made to fit with different piping process applications. Plus, they’re sealed using varying types of elastomer, and you can select an elastomer type that fits within your budget. The downside to these valves is that they’re high-torque and the seat material can’t endure higher temperatures and pressure levels higher than 285 PSI. They also can’t be used in larger applications, as they’re typically found in sizes up to 30 in.
High-Performance Butterfly Valves
High-performance butterfly valves can handle everything that general service butterfly valves can process, but they’re made to withstand the liquids and gases general service valves can’t tolerate. They’re made with PTFE seats that can handle chemically reactive and corrosive liquids, gases and steam. Whereas general butterfly valves are constructed with elastomers that are susceptible to erosion, high-performance butterfly valves use resilient material like graphite to seal the seat. The other plus is that they come in sizes up to 60 in so they can be used for larger applications.
No matter what type of vicious material you’re processing, you can find a high-performance butterfly valve that caters to your needs. If your application runs a risk for fugitive emissions, you can use a high-performance butterfly valve that features stem seal extensions for leak-proof emissions control. If your pipes process extremely cold temperatures, you can find high-performance butterfly valves with pressurized neck extensions that allow for pipe insulation.
You can find high-performance butterfly valves made with carbon steel, stainless steel, and other metals. The metals are welded so that the valve can withstand temperatures as low as -320 degrees F and as high as 1200 degrees F, and endure pressure levels up to 1440 PSI. Most high-performance butterfly valves have a stop in the body that prevents over-travel, and an adjustable packing gland to prevent external leakage.
