Choosing a suitable valve for specific applications is essential in designing a process system. This article will dive into the properties and characteristics of the gate, ball, and butterfly valves and the differences between each type. Knowing how to set these valves apart and how they will interact with your system will help you decide which one best suits your needs.
Because valves are an integral part of piping systems that convey liquids and gases, they are one of the most common components found across most industrial sectors. They regulate liquid or gas flow by allowing it to start and stop, and they must function adequately to prevent leaks and unwanted discharges. They are also effective means to route flows or isolate parts of the piping process for maintenance or monitoring.
Valves come in various sizes and configurations, but their sole purpose is to regulate and control the gas or liquid passing by the pipe. In this article, we will compare the three most common types of valves: gate valves, ball valves, and butterfly valves. We will start by defining each component, exploring what each can do, and what makes them effective, reliable tools.
Defining Gate Valve, Ball Valve, and Butterfly Valve
Here's a closer look at the distinctions between each valve device.
What Is a Gate Valve?
As the name implies, gate valves act as gatekeepers. The term originated from the closing component of the valve sliding into the flowing fluid to induce shut-off, thereby functioning as a gate. They have a flat- or wedge-shaped gate on a threaded stem, and the gate plates move in a straight line parallel to it.
When closed, the gate moves into the flow path and seats into a cavity opposite the stem, creating a solid seal. It is entirely out of the flow path when opened, resulting in zero-flow obstruction or pressure drop. Gate valves work best in high-pressure systems compared to low-pressure systems, where a tight seal is critical and might need special accommodations. A low-pressure operation might lead to seeping at the valve while closed.
These linear motion isolation valves should be kept either completely open or closed as partial opening can cause damage; not used to control medium flow. Gate valves isolate specific areas of the supply network for repair, maintenance, new installation activities, and reroute flow across the pipeline.
Its simple design and versatility in low-pressure drop applications make the gate valve one of today's most commonly used valves. It is designed to be a full-port valve, meaning the valve port is the same size as the inner diameter of a connecting pipe. A full-bore gate valve allows fluid to pass through the pipeline without obstructing or producing a pressure drop. This also makes cleaning the line easier.
Gate valves are widely utilized with bigger pipe diameters, ranging from 2" to the largest pipelines, because they are less complex to design compared to other large-sized valves.
What Is a Ball Valve?
As the name suggests, ball valves are quarter-turn valves that use a rotatable ball with a bore to regulate gas and fluid flow from one opening to the next. The opening is in line with the pipe, allowing the medium to flow freely when turned on. When turned off, the gap is perpendicular to the flow of the medium, stopping it completely.
Also called shut-off valves, ball valves are the only way to shut off medium flow immediately. They are incapable of immediate redirection. Ball valves are best used with gases because they have a robust seal. They can withstand temperatures of up to 350°C and up to 700 bar pressures. Because of their simple structure and compact sizes, typically ranging from 0.5 cm to 30 cm, these valves are easy to use and repair.
Ball valves are known to be durable and reliable, closing securely even after prolonged rest periods and functioning well even after many cycles. Ball valves have a higher resistance to contaminated media than other valve types and provide a good seal despite the unclean medium. These features make them an excellent choice for control and shut-off applications, where gate valves are frequently chosen, but they lack the power of those alternatives in throttling applications.
What Is a Butterfly Valve?
Butterfly valves are named after the rotating disc opening and closing the valve. They are quarter-turn rotational motion valves frequently used to shut off flow in pipelines. Also known as flap valves, butterfly valves are composed of a disc fixed on the valve's stem, and it rotates around the stem to control the flow of the medium in the pipeline. A butterfly valve is fast and easy to actuate, requiring only 90 degrees of movement to move from fully open to close.
Because the disc sits perpendicular to the flow when open, a minor pressure drop and slight flow turbulence are unavoidable. This means butterfly valves are not generally suited for use in processes containing solids, grit, and other abrasive material present in them, particularly in waterworks, as they might collect on the disc and prevent a tight seal when attempting to close the valve. Unlike gate valves, the lack of flow restriction elevates the risk of fluid hammering. Fluid hammering can cause a sudden increase in pressure and damage the instrumentation.
These valves are applied in various processes and industries, including water supply, distribution, collection, and pumping stations. They also have a wide range of uses, especially in flow isolation. Easy fabrication and compactness are two of their primary advantages over other valve types, resulting in lightweight, cost-efficient products with smaller installation footprints and faster actuation rates.
Differences Between Gate, Ball, and Butterfly Valves
The plate moves in a straight line parallel to the stem in a gate valve. These are lightweight valves with a flat bottom seat gate, precision casting valve body, and integral glue coating. Gate valves are shut-off valves designed to fully open and close to allow unrestricted flow.
Ball valves contain a stem and ball which turns horizontally. They are best used in applications requiring on and off control without pressure drop. These valves are characterized by a long service life and provide reliable sealing during their lifespan, even when they are not in use for a long time. As a result, they are more popular shut-off valves than gate valves.
Butterfly valves are small and simple compared to gate and ball valves. Their lightweight and compact design make them ideal for installation in tight spaces. In addition, the disc has a 90-degree reciprocating rotation capacity which makes regulating the flow and facilitating a complete, leak-proof shut-off more convenient.
The gate valve is a complete on-and-off valve. The gate plate, which regulates the media, can only fully open or close. As a result, the pressure drop is minimal, and the flow is bi-directional. The design of the gate is primarily wedge-shaped and does not facilitate flow regulation. The ends of the valve are either threaded or flanged.
The ball valve drives the valve handle to rotate by a transmission, which in turn causes the ball to pivot perpendicular to the media flow. It opens when the ball's hole is in line with the flow and closes when it is spun 90 degrees by the valve handle. While mainly used for non-slurry applications, ball valves are also ideal for applications that need a tight shut-off. The immediate opening and closing of the ball make it essential in some applications that require media isolation.
The disc moves around its axis in a butterfly valve, enabling complete or partial opening and closing. This makes the butterfly valve suitable for partial isolation and flows that need to be regulated. The primary characteristic of this valve is the change in the deflection of the butterfly disc, making it an appropriate choice for large-diameter applications.
Thanks to its robust open and close mechanism, the gate valve has the most minimum pressure drop among other valves. These valves offer no resistance to the flow of fluid, making them unfit for controlled applications. The straight-through flow path provides minimum erosion and turbulence. Media accumulation is almost negligible in gate valves.
Ball valves have an uncomplicated structure and a good sealing performance. They are lightweight, easy to operate, have low material consumption, small driving torque, trim installation size, and offer minimal pressure drop. The ball valve is best used for general working fluids such as water, acids, solvents, and natural gas and media with extreme working conditions, such as oxygen, hydrogen peroxide, methane, and ethylene - making it a versatile option. These valves are commonly used in low-pressure applications.
The butterfly valve's speedy opening and closing speed make it suitable for throttling, flow regulation, and adjustment control. However, the pressure loss is more considerable than the ball and gate valve. Hence, the pressure loss and limitations in operating temperatures should be considered when choosing a butterfly valve.
What Are Lockout Valves?
Lockout valves are devices used by authorized employees to isolate or shut off operating valves to prevent life-threatening accidents from occurring during repair or maintenance work. These lockout devices are different from the valves themselves. They are devices fitted over the operational section of the valve and secured with lockout hasps or padlocks to prevent unauthorized access.
3 Types of Valve Lockout Devices
- Gate Valve Lockout
- Ball Valve Lockout
- Butterfly Valve Lockout
How Do You Use a Valve Lockout?
There are different types of valve lockout, each tailored to a certain type of industrial valve. We'll discuss each of these in detail below:
Gate Valve Lockout Devices
Gate valve lockout mechanisms are classified into two types: rotating and hinged. Rotating gate valve lockout devices have an inward/outward rotating feature, while hinged gate valve lockouts are made up of two half-moons that are hinged on one side.
While their mechanisms differ, both are designed to enclose and cover the gate valve handle in order to prevent unauthorized or accidental valve opening.
Ball Valve Lockout Devices
Ball valve lockouts come in standard and adjustable designs. The standard ball valve lockout has a simple and efficient single-piece design. To use this, simply clamp the lockout/tagout valve device onto the ball valve lever as far as possible and make sure it sits over the angled portion of the handle. Squeeze the valve handle and the LOTO device together, then secure it with a LOTO lock at its closest fit.
On the other hand, the adjustable valve lockout device comes with a two-piece design. To use this, place the base of the lockout device over the ball valve lever, then slip the sliding piece over the end as far as possible to secure the entire device. To complete the lockout, insert the LOTO lock at its closest fit.
Butterfly Valve Lockout Devices
Butterfly valve lockouts have a two-piece design that’s quick and easy to install with no extra tools needed. Simply position the main part over the top of the valve lever, then slide the outer sleeve into the handle to block the release trigger.
Using gate valves, ball valves, and butterfly valves have their advantages and disadvantages, largely dependent on the requirements of the application where they are going to be installed. Generally, gate valve devices are ideal for strict sealing applications and do not require a frequent operation. On the other hand, ball valves are best suited for systems with periodic shut-off requirements. Lastly, butterfly valves are most suited for throttling purposes, occupying less space for massive systems.
In search of premium, industrial-grade, OSHA-compliant lockout valves that offer a fool-proof mechanism to prevent unauthorized use of pipe systems during maintenance or repair services? Visit TRADESAFE and shop our broad selection of premium valve lockouts now.