Control Valve
Control Valve

Even vetted technicians find it difficult to choose a control valve. It is important to have a basic understanding of regulation technologies to choose the right one. Different types of control valves and their applications need to be understood as well.

The flow and pressure of fluids and steam are controlled by control valves, which are powered devices. Control signals determine the degree of regulation (from full capacity to minimal).

The control valve is one of the most important components of an industrial control system. Processes such as liquid level, pressure, velocity, and temperature are controlled by these devices, but within the correct operating range. In addition, they ensure that your equipment will perform efficiently and last for a long time.

The valves are used in a variety of residential and industrial applications. HVAC (heating, ventilation, and air conditioning) systems, unit ventilators, fan coil units, and VAV boxes, among other devices, use them.

Control Valve Types and Categories

All control valves control flow, pressure, and temperature, but they are designed for slightly different applications. Among the most common types of control valves are:

  • Controlled by rotary motion (ball valves and butterfly valves)
  • Control valves with linear action (globes and diaphragms)
  • Control with three directions
  • Controlled by self-action

Let’s take a closer look at these control valves and their features.

Aira Euro Automation is the leading manufacturer and supplier of the control valve in Nigeria. We offer various types of industrial valves like ball valves, butterfly valves, control valves, pressure reducing valves, plug valves, and many more. 

Rotary Control Valve: Types and Functions 

Through rotated passages in a transverse plug, fluid travels through rotary valves (also known as quarter-turn valves). A rotating closure element controls the flow, as the name suggests.

Flexible and compatible with many adaptive technologies, this type of valve is very versatile. The majority of rotary valves are quite compact. However, they can also handle more demanding applications. They are ideal for dirty (particle-heavy) fluids, such as those used in refineries.

Ball Valves

As they provide straight-through flow, ball valves are ideal for isolation applications. Furthermore, they are quick-acting, easily actuated, and have a low-pressure drop. A ball valve can be operated pneumatically, electrically, or manually (depending on its model).

A quarter-turn valve with a round hole in the center has a rugged three-piece body. By using a hollow pivoting ball, ball valves control how many fluids can pass through them.

The ball valve is quite heavy and more expensive than other control valves. However, they work great for high-pressure and high-capacity applications. They can be found in:

  • A building’s control system
  • Industries related to water
  • Industries related to chemicals

Besides hot and chilled water, ball valves can also control glycol mixes and steam. In addition, this type of control valve prevents contamination from outside by limiting cavities and crevices. 

Butterfly Valves

With butterfly valves, high-flow applications are controlled by quarter-turn rotation. Flow can be started and stopped quickly and easily using butterfly valves. Moreover, it minimizes the possibility of leaks by allowing complete closure and opening of the valve.

The valves can be operated pneumatically, manually, or electrically (similar to ball valves). Butterfly valves are much more lightweight and economical than ball valves.

Butterfly valves are available in a variety of construction materials, liner options, and other specifications. Because of this, they are highly compatible with a wide range of industrial, water, and chemical applications.

Due to their low-pressure drop, high-pressure recovery, and excellent flow isolation, these valves are widely used by companies. They are typically used for the following purposes:

  • HVAC systems
  • Exhaust gases control
  • High-temperature services
  • Steam services

Also, read “AN OVERVIEW OF AIRA’S LINED BUTTERFLY VALVE

Linear Control Valve: Types and Functions

In linear valves (multi-turn valves), the closure is pushed into the open and closed positions by a sliding-stem mechanism. Despite its slower operation speed, this control valve has excellent positional stability and accuracy (1:1 flow control).

There are several advantages to linear valves, including their simplicity and durability. Due to the wide range of trim sizes and options available, these valves are also very versatile. There are several types of linear valves, including globe valves and diaphragm control valves.

Globe Valves

In pipelines and other applications requiring increased flow resistance or significant pressure drops, globe control valves are used to regulate flow.

The bodies of these valves are generally spherical. There are two halves to the mechanism, a moveable plug (disc element) that separates them, and a stationary ring seat. Globe valves also have a stem that moves up and down in the valve to regulate the flow.

Globe valves offer excellent efficiency and reliability for a wide range of applications, including:

  • Feeding systems for chemicals
  • Steam vents and boilers
  • Water cooling systems
  • Fuel oil systems

The globe valve is one of the most expensive devices on the market. Despite this, they provide extended service life, high performance, and optimized flow passages to reduce pressure drops and destructive turbulence.

Diaphragm Control Valves 

A diaphragm valve (membrane valve) consists of a plastic, wood, or metal body with multiple ports and an elastomeric diaphragm. It is controlled by the seat in the body that opens and closes the valve.

Due to their tight seal, these valves eliminate any possibility of contamination. By doing so, you can ensure that the liquids in your systems remain sterile and clean.

Due to their wide range of designs and construction materials, diaphragm control valves can use in many systems. These valves can also regulate corrosive and abrasive media, in addition to clean water. To enhance control accuracy, you can also use them with pneumatic control heads or process controllers.

Three-Way Control Valve

The three-way control valve allows fluid flow in one pipe to openwhile the flow in another closes. Pneumatic, multi-spring, or electric actuators typically use power these valves.

There are two types of three-way flow control valves: diverter valves and mixing valves.

HVAC systems use these valves to control water, oil, steam, and other fluids. Three-way valves typically use the following applications:

  • Air handling units
  • Boilers
  • Fan coils
  • Water chillers

Self-Acting Control Valve

Temperature-sensitive fluid regulates the flow of water through a self-acting valve. When heated, this fluid expands, and when cooled, it contracts. By transferring the force created by these reactions to the actuator, the valve opens and closes.

Water and steam regulate these valves in heating and cooling systems. Typical applications of self-acting control valves include:

  • Compressors of air
  • Chilled air
  • Steam boilers
  • Engines for industry

Easy installation and enhanced durability are some advantages of self-acting valves. In addition, these valves are self-sufficient, meaning they don’t require external power.

Popular Applications of Control Valves in the Industry 

Flow, pressure, and temperature of fluids (and other substances) are the primary functions of control valves. In addition, control valves can regulate air, steam, glycol mixes, and chemicals according to predefined settings.

Chemical manufacturing, refining, and other industrial processes use control valves. Process quantities and consequential control these valves. How do these valves work?

  • Loops control by control valves.
  • At the beginning of the loop, a transmitter and a controller compare the current flow level with the desired level.
  • Control signals are sent from the controller to the valve (control device).
  • Control valves reduce fluid flow (or increase it) by closing or opening.
  • To maintain the desired flow level, the valve opens or closes.

Various industries use a variety of control valve types and applications. Other industries include food & beverage, oil & gas, pipeline, and biopharma.

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