Views: 37 Author: Site Editor Publish Time: 2023-01-13 Origin: Site
Getting into the details of butterfly vs gate valve, we first need to understand what they are. The valves used in a plumbing system are one of the most important parts. Valves control liquid flow by enabling it to start and stop; they must be in good working order to avoid leaks and unintended flow.
Two of the most popular industrial valve types are the gate valve and the butterfly valve. There are many other varieties of valves that are accessible. These two have very distinct structural layouts, applications, and operating philosophies.
The gate valve belongs to the cut-off valve category and can only be used in completely open or fully closed positions; there is no provision for flow regulation. A fixed disc that circles around the stem of the valve shaft to open and close is the foundation of a butterfly valve sometimes referred to as a flap valve.
Here is a complete guide about butterfly valve vs gate valve.
What Is A Butterfly Valve
Pipeline flow can be stopped using butterfly valves, a form of a quarter-turn rotational motion valve. It is well knowledge that butterfly valves can be used to regulate flow. This is not advised, though, since it may damage the valve disc and jeopardize the sealing properties. Open and use of butterfly valves is straightforward.
Rotating the handle 90 degrees will close or open the valve entirely. Large Butterfly valves frequently have a gearbox, which uses gears to connect the handwheel and stem. The valve can now be operated more easily, but speed is sacrificed in the process.
These valves have a wide range of purposes, particularly in flow isolation, and are used in a wide range of process media and industries, including water supply, distribution, and the collection as well as pumping stations. Two of their main advantages over other valve families are ease of fabrication and compactness, which lead to lighter weight and less expensive final products with smaller installation footprints and faster actuation rates.
The butterfly valve with zero offsets, which depends on the rubber’s flexibility, has the lowest pressure rating. The high-performance double offset butterfly valve, which is used in systems with a little bit higher pressure, is offset from the centerlines of the body seal, the disc seat, and the bore (offset one, offset two).
This creates a cam motion during operation to elevate the seat out of the seal, resulting in less friction and a lower tendency to wear than the zero offset design. For high-pressure systems, the triple offset butterfly valve is the ideal valve.
This valve’s offset disc seat contact axis efficiently prevents sliding contact between the disc and the seat. In order to be machined to produce a bubble-tight shut-off when it comes into contact with the disc, the seat of a triple offset valve is made of metal.
Butterfly Valve Parts
The body, disc, stem, and seat are the only four essential parts of a butterfly valve.
Body
The bodies of butterfly valves typically slide between two pipe flanges. Lug and wafer body styles are the most popular. Bolt holes that match those in the pipe flange are provided by protruding lugs on the lug body. The lugs on a wafer body are not projecting. The pipe flanges and the wafer valve are sandwiched together, and the body is encircled by the flange bolts.
Every body type offers benefits. Compared to the lug style, the wafer style is more affordable. Wafer designs prevent the weight of the pipe system from passing through the valve body directly. A lug body enables the removal or service of downstream piping dead ends.
Disk
The disc is a butterfly valve’s flow closing component. In an effort to increase flow, sealing, and/or operating torque, numerous modifications to the disc design have been made in relation to the orientation of the disc and stem.
A plug-in a plug valve, a gate in a gate valve, or a ball in a ball valve are analogous to the disc. The butterfly valve can be opened and closed by rotating the disc 90 degrees or one-quarter turn.
Stem
The butterfly valve’s stem can be either a two-piece (split-stem) design or a one-piece shaft. In most resilient seated designs, the stem is shielded from the media, allowing for an effective material choice in terms of price and mechanical attributes.
The stems in high-performance designs must be compatible and have the necessary strength to seat and dislodge the disc from the seat since they come into touch with the media.
Seat
A resilient-seat butterfly valve’s seat provides cutoff through an interference fit between the disc edge and the seat. Various elastomers or polymers can be used to make the seat’s material. The seat may be pushed or locked in, or it may be glued to the body.
An interference-fit seat design or a line-energized seat design, where the pressure in the pipeline is employed to increase interference between the seat and disc edge, may be used to achieve the shutoff in high-performance butterfly valves. Polytetrafluoroethylene (PTFE) or reinforced PTFE (RTFE) is the most used seat material due to its greater range of compatibility and temperature range.
High-performance butterfly valves can also be found with metal seats. These metal seats enable the use of a butterfly valve in temperatures up to 1,000 degrees Fahrenheit. There are fire-safe designs available that offer polymer seat valve shut down prior to a fire and metal seal backup shutoff during and after a fire.
Butterfly Valve Working Mechanism
A butterfly valve working principle is similar to a ball valve, enabling quick shutoff. Because they are less expensive than other types of valves and lighter and smaller, butterfly valves are preferred because they require less support. In the middle of the pipe is where the disc is located. The actuator on the valve’s outside is connected to the disc by a rod.
Rotating the actuator causes the disc to move perpendicular or parallel to the flow. Unlike a ball valve, the disc is always present in the flow and lowers pressure even while it is open. The quarter-turn valve family of valves includes butterfly valves.
The valve is fully open or closed when the disc is turned a quarter turn. Butterfly valves are capable of shutting off and permitting two-way flow. However, because they are not full-bore, they cannot be used for swabbing or pigging.
Butterfly Valve Applications
Let us now see the gate valve vs butterfly valve application. Industrial butterfly valves are more portable than gate valves, which makes them simpler to install and operate in circumstances involving wide pipe lengths. They are ideal for installations in restricted spaces, where wafer butterfly valves are suggested. In practice, butterfly valves are used more commonly in large sizes compared to gate valves.
Because they may be operated often and open and close quickly, butterfly valves are ideal for applications that call for emergency shutoffs. They are used for truncation as well as to change or throttle flow rates. Butterfly valves are the best choice for pipes carrying minute contaminants.
Since they can be utilized in conditions with moderate to high temperatures and pressure, butterfly valves are additionally referred to as high-performance valves.