Valves are mechanical devices used to control, direct, and regulate the flow of water by opening, closing, or partially obstructing the flow. They can be made up of different materials like bronze, PVC, brass, etc.
Valves are employed in residential and commercial buildings, water supply systems, wastewater treatment plants, and chemical plants to direct the flow, shut off water access, prevent backflow, and adjust water pressure within a system.
This article discusses the five major types of valves, their types, advantages, and disadvantages.
- Types of Valves
- 1. Gate Valve
- 2. Butterfly Valve
- 3. Ball Valve
- 4. Globe Valve
- 5. Pressure Relief Valve
Types of Valves
1. Gate Valve
Gate valve is the most widely used type of valve in plumbing systems. It includes a wedge-shaped metal gate that can be lowered (with the use of a twist-type handle or knob) to stop the flow of water or raised to allow the flow to continue.
Gate valves cannot control the water flow as they are designed to be fully opened or fully closed. If used to adjust the water flow, it can wear out the valves. Gate valves can be used for the circulation of all types of fluids, such as air, fuel gas, feedwater, steam, lube oil, and hydrocarbons.
Gate valves are further classified into different types as mentioned below:
- Solid wedge gate valve
- Flexible wedge gate valve
- OS&Y gate valve or rising stem valve
- Non-rising stem gate valve or insider screw valve
- Split wedge or parallel disks gate valve
Advantages of Gate Valves
- The gate inside the valve retracts entirely into the body, due to which the valve does not impede the water flow.
- Due to the slow opening and closing of the valve, the water pressure is modified gradually, which protects the pipe from the banging sound of the water hammer.
Disadvantages of Gate Valves
- Due to repeated usage, the valve's seat can wear down, thereby weakening the valve's seal and reducing the valve's efficiency.
- The raising and lowering of the valve can only be operated manually, which can be time-consuming.
2. Butterfly Valve
This valve has a rotating metal disc that allows and inhibits the water flow, creating an image similar to that of a butterfly due to which is called a butterfly valve.
These valves are very compact, light, and relatively short, making them significantly lighter than the other types.
Types of Butterfly Valves
- Double offset butterfly valve
- Triple offset butterfly valve
- Flanged ends
- Wafer type ends
- Lug type ends
- Butt-welded types end
- Zero offset butterfly valve
Advantages of Butterfly Valves
- Butterfly valves are lighter and less expensive than ball valves.
- Due to their compact size, they are prevalent in industrial applications.
Disadvantages of Butterfly Valves
- Butterfly valves rely on a gasket which eventually needs to be replaced.
- The butterfly disk which regulates the flow lies within the water (even when fully opened), due to which pressure drop is observed.
- Butterfly valves are less durable and slower to operate.
3. Ball Valve
Ball valves are the most reliable and common type of valves used to regulate the flow of water. It involves a rotating sphere with a hole that is attached to a lever handle to operate the valve.
In the open position, the hole in the sphere is in line with the pipe, allowing the water to flow through it. When in a closed position, the hole in the sphere is perpendicular to the pipe, thus completely restricting the water flow. The lever handle also serves as an indicator of whether the valve is open or closed. When the lever is perpendicular to the pipe, the valve is closed.
Types of Ball Valves
- 3 Way ball valve
- Three-piece body
- Trunnion mounted ball valve
- Floating ball valve
- Side entry or split body
Advantages of Ball Valves
- They provide an excellent seal in a closed position.
- Ball valves are lighter and smaller than gate valves of the same size and rating.
Disadvantage of Ball Valves
- Ball valves do not permit precise flow control because they usually have positive stops (0, 45, 90 degrees).
4. Globe Valve
The Globe valve is commonly used to regulate or limit the water flow in plumbing applications, where the flow needs to be adjusted regularly.
The interior design features contain a stopper on the end of a valve stem that is raised and lowered by the valve's twist knob. Globe valves get their name due to the globe-like or ball-like appearance of their body.
The globe valves are suitable for regulating flow; they are often used for outdoor faucets (hose bibs) and similar utility faucets.
Types of Globe Valves
- Z types
- Y types
- Angle types
Advantages of Globe Valves
- Globe valves are used in places where the flow needs to be adjusted regularly and needs not be fully open.
- They are easy to maintain and have effective throttling and shutoff abilities.
Disadvantages of Globe Valves
- Globe valves cannot be operated in completely open conditions since the baffle restricts the flow.
5. Pressure Relief Valve
Pressure relief valves are used in the plumbing system to reduce water pressure to the desired limit and protect equipment or piping systems from bursting. The mechanism consists of a spring and diaphragm adjusted to a specific limit, depending on the pressure of the water supply.
The pressure relief valves are also known as pressure-reducing valves, pressure safety valves, and pressure balance valves.
Types of Pressure Relief Valves
- Reclosing-type pressure relief devices
- Non-reclosing type pressure relief devices
- Safety relief valves
- Pressure relief valve
- Vacuum relief valve
- Pressure vacuum relief valve
Advantages of Pressure Relief Valves
- Very reliable if properly sized and operated
- Versatile- can be used in a range of services such as firefighting, high-rise buildings, water towers, drinking water applications, and water tanks.
Disadvantages of Pressure Relief Valves
- Relieves pressure in the pipeline, which is caused due to backpressure.
- Susceptible to chatter if built-up back pressure is too high
The five major types of valves used in the plumbing system are:
1. Gate valve
2. Butterfly valve
3. Ball valve
4. Globe valve
5. Pressure relief valve
The applications of a valve in residential and commercial buildings, water supply systems, wastewater treatment plants, and chemical plants are to direct flow, shut off water access, prevent backflow, and adjust water pressure within a system.
Ball valves are the most widely used type of valves that are installed to regulate the flow of water. It involves a rotating sphere with a hole that is attached to a lever handle to operate the valve.
Pressure relief valves are used to reduce water pressure to the desired limit and protect equipment or piping systems from bursting.