What are the Different Types of Control Valves?

What is a control valve? What are the various types to choose from? These questions often pop up in the mind of the buyer. Choosing the right control valve requires a basic understanding of the various types that are available in the market and their applications.  Let us know more:

What is a Control Valve?

When it comes to industrial control systems, control valves play a vital role. Their function is to control the flow and pressure(of liquid or steam) in a machine. They have a controller that regulates and keeps a check on the flow. There are various types of control valves are commonly used in both residential as well as industrial applications. Control valves are necessary and ensure long life of your equipment. One can keep a check on the pressure and velocity also.  

Types of Control Valves:

There are hundreds of control valves available in the market. Some of them include:

• Rotary control (ball and butterfly valves)
• Linear control (globe and diaphragm valves)
• Three-way control
• Self-acting control

Let us read in detail about the above-mentioned valves and their features.

Rotary Control Valves: 

These valves function by controlling the passage or passages to control the flow. They function well under demanding conditions. This makes them a perfect solution to be used for heavy particle fluids. Let us look at the further segregation of rotary control valves. 

1. Ball Valves: 

Ball valves use a pivoting ball to control liquid flow and air flow. There is a stem at the top of the ball which rotates the ball to open or close the valve. 

Advantages: 

• They are highly durable
• They are efficient and easy to install
• They are best for high-pressure applications.

Disadvantages:

• Their accuracy is limited
• They can be slow to open and close

Suitability of Ball Valves: They are ideal for high-capacity and high-pressure applications.

2. Butterfly Valves:

Butterfly valves use a rotating disc to start and stop the flow with ease and are used for high-flow applications. They permit complete opening and closing of the valve which helps in minimizing potential leakage. 

Advantages:

• They have a low-cost
• They require low-maintenance
• They are compact

Disadvantages:

• They are not ideal for high-pressure applications
• They are prone to leakage

Suitability: They are compatible with HVAC systems, exhaust gas control systems, high-temperature services and stream services. 

Linear Control Valves: 

These control valves are also known as multi control valves. They regulate the flow of liquid accurately with the help of a valve stem  or a liquid. They come in many trim sizes and designs.

They are ideal for systems that have a constant pressure drop.

1. Globe Valves

Globe valves are generally spherical. They are made up of a variety of materials including carbon steel, cast iron, stainless steel, cobalt etc. It consists of a moveable plug, a stationary ring seat and a stem. 

Advantages:

• They are durable and reliable
• They have a low leakage

Disadvantages:

• They are heavy
• They have a low opening speed
• They are expensive

Suitability: They are ideal for chemical feed systems, cooling water systems, fuel oil systems, and boiler and main steam vents.

2. Diaphragm Control Valves: 

Diaphgram control valves comprise of plastic, wood or metal along with multiple ports. They can be operated manually or automatically. They function by controlling the area from where they enter and exit. 

Advantages:

• They can function in a wide temperature range.
• They help in preventing contamination.

Disadvantages:

• They can wear out with time.
• They are not suitable for extreme circumstances.

Three-Way Control Valves

These valves are comprised of either pneumatic, multi-spring, or electric actuators. They allow water to shut off in one pipe and open flow in another pipe. 

Advantages: 

• It allows different media to flow in the same direction.
• It can mix two media types

Disadvantages:

• They have a limited flow capacity
• They might be difficult to install

Suitability: Three-way control valves are ideal to be used for boilers, fan coils, water chillers and air handling units. 

Self Acting Control Valves: 

These valves keep a check on the water flow with the help of a temperature-sensitive fluid. This fluid expands when heated and contracts on cooling. 

Advantages: 

• They can easily be installed.
• They do not require any additional power to operate

Disadvantages: 

• They can bear only a certain amount of pressure

Suitability: These valves are best suited for boilers and industrial engines. 

Industrial Applications of Control Valves:

Many industries including refining industries and chemical manufacturing industries find usage of control valves for effectively and efficiently controlling the flow of liquids and gases in equipment. Some other major applications include food & beverage industries, oil & gas industries, pharmaceutical industries & many more. 

Conclusion: 

• Control valves are used in many industries and ensure efficient flow of gases and liquid in an equipment.
• All the different types of control valves mentioned in this article have their distinct features and form an integral part various industrial equipment. 
• Investing in the right type of control valves and properly maintaining them increases efficiency and profitability of the business. 

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