Valves play an integral role in conveying liquids and gases in home and industrial piping systems. They are available in various sizes, designs, and types, for regulating and safely controlling these media. In this article, we will discuss butterfly valves and gate valves, the two most popular types of industrial valves.
While a gate valve is incredibly adaptable and employed in a variety of media with granular materials and high viscosity, including steam, oil, and other liquids, a butterfly valve is perfect for operations with temperatures and pressures ranging from moderate to high. Due to its compact form, it needs less installation area and is more economical in larger sizes.
Although both may serve near-similar purposes, they have considerable differences in their structural design, usage, size, and working conditions. So, let’s learn about butterfly valve vs. gate valve in detail here!
What is a Gate Valve?
Also known as a sluice valve, a gate valve is most commonly used for water delivery systems. It features linear-motion isolation that helps stop and let the flow of liquids and gases through. Its name originates from the closing component contained in the system that slides into the flowing fluid to induce shut-off, functioning as a gate or shut-off.
These valves help isolate specific areas of the water supply network for repair and maintenance. If you want to carry out installation activities or reroute the water flow across the pipeline, a gate valve will assist you throughout. However, it must not be used to control the flow; instead, completely opening or closing because partial activity can cause damages.
A gate valve features a simple yet versatile design that helps low-pressure drop applications. It is one of the most commonly used valves because of its full-port design, with a size similar to the inner diameter of the joining pipe. It is available in various temperatures, sizes, materials, and pressure ratings, and styles that you have plenty to choose from.
A full-bore gate valve’s primary function lets the liquid pass through the pipeline without any obstruction or pressure drop production, making it easier to clean the pipe using a pig. Since it features a less complex design than a butterfly valve working principle, gate valves are widely preferred with larger pipe diameters, beginning from 2-inches.
Resilient seated gate valves are classified into three styles:
- Disk Designs
- Solid taper wedge
- Flexible wedge
- Split or parallel disk wedge
- Body Bonnet Joint Designs
- Screwed bonnet
- Bolted bonnet
- Welded bonnet
- Pressure-seal bonnet
- Stem Movement Designs
- Rising stem or OS/Y type (Outside Screw & Stem type)
- Non-rising stem type
What is a Butterfly Valve?
A butterfly valve is a quarter-turn rotational motion valve whose primary function is to block media flow in pipelines. It is commonly used for influencing the flow; however, it’s not safe because it can harm the valve disk and undermine the sealing features. It works fine if only used for ultimately allowing and stopping the flow by rotating the handle to 90 degrees.
A large metal seated butterfly valve has a gearbox for connecting the handwheel to the stem through gears, making their operation more effortless but at the expense of speed. This valve is widely used in various process media and industries, including water distribution, supply, and collection. In pumping stations, it also has multiple uses, especially in isolating the flow.
The primary advantage of using a butterfly valve in industrial applications is compactness and easy fabrication over other valve families. These benefits contribute to the valve’s lightweight and low-cost end product with minimal installation tracks and quicker actuation rates.
Also known as flap valves, a butterfly valve is found in a variety of shapes and sizes, suiting to certain pressures and purposes. There are basically the following disk offset patterns for these devices:
- Concentric or Zero Offset Butterfly Valve
- Double Eccentric or Offset Butterfly Valve
- Triple Eccentric or Offset Butterfly Valve
Furthermore, a butterfly valve is found in the following varied body designs:
- Lug-type Butterfly Valve
- Wafer-type Butterfly Valve
- Flanged Butterfly Valve
- Butt-welded Butterfly Valve
A zero offset type butterfly valve depends on rubber flexibility and has the lowest pressure rating. On the other hand, the double offset valve type provides high performance and is usually used in high-pressure systems. It is offset from the centerline of the body seal, the disc seat, and the centerline of the bore, resulting in a cam stirring during operation to raise the seat from the seal, resulting in reduced friction and wear tendency.
A triple-offset butterfly valve working principle is best suited for high-pressure systems. In this valve, the disc seat contiguity axis is offset, effectively eradicating the sliding touch between it and the seat. Its seat is constructed using metal, making it machined to produce a bubble-tight closing when it comes in contact with the disc.
How is a Gate Valve Different from a Butterfly Valve?
Now that we have learned about both these valves, let’s know how these two are different from one another. We will talk about their design, working mechanism, and applications. So, let’s discuss a butterfly valve vs. gate valve in detail!
In wedge gate valves, a wedge is used, while in butterfly valves, there is a rotating disc for allowing or obstructing the flow of fluid in the pipeline. Moreover, they have entirely different body and disc designs from one another.
The body-bonnet design of a gate valve includes a bolted bonnet, screwed bonnet, pressure seal bonnet, and a welded bonnet. While its design features a wedge, disc, and a conduit or parallel slide, the butterfly valve working principle has a lug, a wafer, a flanged, and a butt-welded type. At the same time, its disc offset design includes a zero offset (concentric), double offset ( eccentric), and a triple offset (eccentric) type.
Since gate valves have excellent sealing properties, they are used in pipelines requiring tight sealing but not frequent switching. One can employ them only in fully open or closed states but not for regulating or throttling the flow rate since it is hard to control it accurately. If the valve is kept partially open, its seat and gate will degrade over time, causing vibrations and noises in the pipeline by the chattering wedge.
Furthermore, since a gate valve’s opening and closing functions are slow compared to that of a butterfly valve, they are not suitable for pipelines requiring immediate shut-offs. But they can sustain high pressure along the pipeline. They are frequently used in large systems, demanding continuous bidirectional flow and time-based unidirectional medium discharge.
On the other hand, an industrial butterfly valve is lightweight, easier to use, and installed in situations needing large pipeline width. A wafer butterfly valve working principle is best for small space installations because of its convenience. They are more frequently applied in large-sized applications than gate valves.
A high-performance butterfly valve is perfect for applications demanding quick opening and closing as it works swiftly and continuously during emergencies. It is suitable for pipelines having tiny contaminants and for throttling and altering the flow rates in addition to truncation. It is ideal for situations demanding moderate to high temperatures and pressures.
Under normal conditions in a butterfly valve vs. gate valve state in terms of specifications, diameter, and material, a lug-type butterfly valve is more affordable than a gate valve. You might find a gate valve at a lower price in a smaller size, but it increases rapidly with the growth in caliber diameter. So, in bigger sizes, butterfly valves are affordable, making them widely used in industries.
In butterfly valve vs. gate valve, we’ll first discuss a gate valve that uses a movable door for opening and closing purposes. Its gate, a solid rectangular or circular disc attaching to the stem, is lowered or raised using a mechanical operator, usually a threaded screw. It features a handwheel, popularly known as the actuator used for operation purposes.
In the open state, this energy transforms the system thread into a gate and vice versa when it is in the closed state. As a result, the gate moves up and down. Since its door can fully open and close, the obstruction to fluid flow when the valve is in the open state is minimal because the gate is entirely out of the medium’s path.
Also referred to as multi-turn valves, which require more than a 360 degrees rotation to open or close, stainless steel gate valves act as obstructions to the flow and are in charge of their speed rather than the flow rate. When the wheel rotates clockwise, the stem and gate move downwards across the fluid flow, and the gate adjusts between the seats. As a result, there is no leakage when the valve is completely closed.
Contrastingly, when the handwheel moves anti-clockwise, the stem and gate move in the upward direction across the fluid flow line, causing the valve to open and allowing the fluid to flow through the gate. Moreover, closing and opening speeds in these systems are slow due to their high rolling height.
There is a non-linear relationship between the vertical movement of a gate valve and its flow rate, with the significant alterations occurring near the closing. It can be used in a partially-open position caused by a high-velocity medium hitting the gate but can lead to gate erosion. Due to these reasons, it should only be used in a completely open or closed state.
A butterfly valve working principle resembles a ball valve that allows rapid shut-off. Compared to other valves, they are cheaper, lightweight, and require minimal support. In a butterfly valve design, a disc is located in the middle of the pipe and a rod on the outside, connecting the actuator and disc. The disc is turned perpendicular or parallel to the medium flow by turning the actuator.
Unlike a ball valve, the disc in a butterfly valve is active in the flow, causing a pressure drop even in the open state. By rotating it quarterly, one can fully open or close it down. A metal disc is fixed on the rod, reflecting as a butterfly. They have a shorter functioning time than gate valves because the disc rotates only 90 degrees to prevent and allow fluid flow thorugh the pipeline.
The disc is rotated quarterly for opening the valve, and for closing it, the disc spins until the pathway is completely blocked. These valves can shut off and allow the flow to move in all directions. However, since they are not full-bore, they are not suitable for pigging and swabbing purposes.
Functions & Usage
As the sealing performance of a gate valve is excellent, it is often used in systems requiring strict sealing but not frequent switching. It is used to cut off the circulating medium but not to regulate the flow rate. Since its opening and closing speed is slow compared to a butterfly valve, it is unsuitable for pipelines requiring immediate shut-offs.
A butterfly valve working principle is widely used for truncation and flow rate adjustments. Since it opens and closes smoothly, it is suitable for systems requiring instant functioning. As a butterfly valve is smaller in size and lightweight, it is perfect for situations with limited installation space. Because of these perks, butterfly valves are slowly becoming the primary choice of users around the world.
Both gate and butterfly valves are extensively found in industrial systems, but they still have differences in their structures, usage methods, price, and adapting to working conditions. We hope this article has helped you learn about butterfly and gate valves and their differences in detail. Please don’t hesitate to contact us to purchase premium quality valves for your home or industrial applications.