Views: 7 Author: Site Editor Publish Time: 2022-11-18 Origin: Site
1. Main Types Of Butterfly Valves
There are two broad families of butterfly valves. Briefly, the difference is whether the stem is concentric with the centerline of the valve body or eccentric or slightly off-centre in two or three planes. This geometric difference is responsible for the differences in the way that various butterfly valves seat and shut off. These two groups overlap somewhat in rating and performance, but in the operational characteristics that really matter, such as pressure rating and shut-off ability, these two types of valve are quite different. Needless to say, because the two valves look quite alike (that is, they both are often very short face-to-face and often do not have separate flanges of their own, and they both have a disc that turns inside the pipe) and they share the butterfly valve name, they are often confused.
2.Advantages
Here are some of the advantages of butterfly valves compared with other valve types.
--Lightweight and compact
--Easy to install
--Low-pressure loss
--Low maintenance
--Simple, rapid operation
3. Disadvantages
The disc can interrupt flow even when it is open
Not recommended for high differential pressures
4. Parts of a Butterfly Valve
Generally, there are four main parts: the stem, disc, seat and valve body.
5. Common Butterfly Valve Applications
Some processes need more tolerant and wear-resistant valves with special features. Below are some common applications that rely on the unique mechanisms of a butterfly control valve.
Food Processing
Simple design, high durability, and low maintenance are the features needed to regulate fluid flow in any piping system. Certified Food Grade Seat is best for the Food Processing sector, so a White seat is preferred.
While standard resilient seated valves are not 3A approved, there are many on the market that maintain sanitary connections inside and outside. The body material for the valve can range from Epoxy coated iron to Nylon 11 coated iron to Bronze, 304SS, and 316SS.
Refineries
The butterfly valve is commonly found in refineries. These would typically use the more “high end” High-Performance valve with Steel Bodies, or the Triple Offset design that is “Fire Safe” and bubble tight. Many applications involving water use the resiliently seated version.
Shut Off Valves
A butterfly valve is often the best choice as a general shut-off valve above 1.5”-148”. Their simple design allows them to take up less space and less weight than other types of valves. These valves provide a tighter seal than a gate of globe valve and are usually bubble tight. This is most useful when trying to stop the fluid flow as it prevents any fluid from passing through the pipe when closed.
Ship Building
Because of their high durability in saltwater, butterfly valves are commonly used in ships where ABS-approved materials are selected. This type of valve effectively creates a water-tight shutoff in the piping system of a ship to prevent any flow in the pipe. Their small size also allows them to be used in those tight spaces that are common aboard the ship.
They can be used for “jack up” rigs, ballast systems, ship side, and many other applications. Fire Safe approved valves are also necessary for many applications. Additional capabilities are automation and pneumatic function (“closed-loop” pneumatic underwater, electric, and hydraulic).
Be sure to use valves with an ISO-5211 mounting pad and stem. This way it’s easier to get a drop-in replacement at any port. Also, be wary of valves that just have an ISO-5211 mounting pad as the stems are often manufacturer’s “special.”