Choosing a control valve is challenging even for vetted technicians. To choose the right one, you should possess a basic knowledge of regulation technologies. You also need an understanding of different types of control valves and their applications.
Now, what is a control valve, and what types of valves exist? At Blackhawk Supply, we'll be happy to share what we know!
Keep reading to learn about the technology behind control valves, their categories and types, and their various industrial applications.
The control valve is a power-operated device designed for controlling the flow and pressure of fluids and steam. The degree of regulation (from full capacity to minimal) is based on the signal from a controller.
Control valves are an essential component of industrial control systems. These devices are used to control processes, such as liquid level, pressure, velocity, and temperature, but within the correct operating range. Additionally, they ensure efficient operations and the long-lasting service life of your equipment.
These valves are used in many residential and industrial applications. For example, you can find them in HVAC (heating, ventilation, and air conditioning) systems, unit ventilators, fan coil units, VAV boxes, and various other devices.
All control valves share the same goal (flow, pressure, and temperature control), but they are designed for slightly different applications. The most widespread types of control valves are:
Rotary control (ball and butterfly valves)
Linear control (globe and diaphragm valves)
Three-way control
Self-acting control
Let's look at these control valves and their features in greater detail.
Fluids in the rotary valves (also known as quarter-turn valves) travel through rotated passages in a transverse plug. As the name suggests, they use a rotating closure element to control the flow.
This type of valve is very flexible and is compatible with many adaptive technologies. Most rotary valves are quite compact. At the same time, they work with demanding applications. Their design makes them great for dirty (particle-heavy) fluids, such as those used in refineries.
Ball valves are extremely useful for isolation applications, as they provide straight-through flow. On top of that, they are quick-acting, easily actuated, and offer a low-pressure drop. Ball valves can be operated pneumatically, electrically, and manually (based on their model, of course).
These valves have a rugged three-piece valve body in the form of a quarter-turn valve with a round hole in the center. A ball valve uses a hollow pivoting ball to control how much fluid can flow through it.
Ball valves are pretty heavy and more expensive than other control valves. However, they work great for high-capacity and high-pressure applications. You can find them in:
Building control systems
Water industries
Chemical industries
In addition to hot and chilled water, the ball valve offers excellent control of glycol mixes and steam. Plus, this type of control valve limits cavities and crevices, preventing contamination from outside sources.
Butterfly valves use quarter-turn rotation for control in high-flow applications. The butterfly valves provide a fast and easy way to start and stop the flow. Additionally, it allows for complete closure and opening of the valve, minimizing potential leakage.
These valves are operated pneumatically, manually, or electrically (akin to ball valves). Unlike a ball valve, a butterfly valve is a much more lightweight and economical solution.
Butterfly valves come in different construction materials, liner options, and other specifications. This makes them highly compatible with a wide range of industrial, water, and chemical applications.
Most companies use butterfly valves for their low-pressure drop, high-pressure recovery, and excellent flow isolation. Their typical applications include:
HVAC systems
Exhaust gases control
High-temperature services
Steam services
The plug control valve is a type of valve used to regulate the flow of a fluid in a pipe. It is a type of gate valve, and it consists of a cylindrical plug that slides in and out of the pipe to control the flow. The plug is connected to a stem, which is turned to open and close the valve. The stem is connected to a handle, which is used to operate the plug valve.
The plug valve is used in a variety of applications, including controlling the flow of water in a pipe, regulating the pressure in a pipe, and controlling the flow of oil in a pipeline. It is widely used in the oil and gas and in the food and beverage industries to control the flow of liquids in a pipe.
Linear valves (multi-turn valves) use a sliding-stem mechanism to push the closure into the open and close positions for flow control. This control valve has a slower operation speed but great positional stability and accuracy (1:1 flow control).
Linear valves have a straightforward and durable design. These valves are also very versatile due to a large variety of available trim sizes and options. Some of the most prevalent subtypes of linear valves are globe valves and diaphragm valves.
Globe control valves regulate flow in pipelines and other applications requiring increased flow resistance or significant pressure drops.
These valves have a generally spherical valve body. The mechanism consists of two halves, a moveable plug (disc element) that separates these halves, and a stationary ring seat. In addition, the globe control valve has a stem that regulates the flow by moving up and down in the valve.
The efficiency and reliability of globe valves make them an excellent choice for a wide selection of applications, including:
Chemical feed systems
Boiler and main steam vents
Cooling water systems
Fuel oil systems
Globe valves are pretty expensive devices. However, they provide extended service life, high performance, and optimized flow passages that reduce pressure drops and destructive turbulence.
Diaphragm valves (membrane valves) are typically made of plastic, wood, or metal body with multiple ports and an elastomeric digraph. The seat in the body opens and closes the valve, controlling the flow.
These valves eliminate any chance of contamination due to their tight seal. This helps to ensure the liquids in your systems remain as sterile and clean as possible.
You can use diaphragm valves in many systems, thanks to a wide range of designs and construction material options. In addition to clean water control, you can use these valves to regulate corrosive and abrasive media. You can also use them with pneumatic control heads or process controllers to enhance the accuracy of control.
Three-way control valves are designed to open fluid flow in a pipe while closing the flow in another pipe. These valves typically have a pneumatic, multi-spring, or electric actuator for power.
A three-way flow control valve is available in two configurations: a diverter valve and a mixing valve.
These valves can control water, oil, steam, and various fluids in HVAC systems. The typical applications of the three-way valve include:
Air handling units
Boilers
Fan coils
Water chillers
A mixing valve is designed to control the supply of water in heating and cooling systems. Basically, these devices provide an easy way to mix hot and chilled waters for a comfortable temperature.
A diverter valve is named after a mechanism that opens and closes the valve in combi boilers to regulate water. The typical places where you can find diverter valves include:
Home radiators
Showerheads
Taps
Diverter valves aren't used for standard HVAC systems and conventional boilers. Instead, they are installed in systems that supply heated water on demand.
Some types of valves, like Tee-Piece valves, combine both mixing and diverting functions. They can accept an ON/OFF or modulating signal. These valves can be used in combi boilers, showers, radiators, and regular HVAC systems.
A self-acting valve regulates the water flow with the help of temperature-sensitive fluid. This fluid expands on heating and contracts when cooled. The force created by these reactions transfers to the actuator, which opens and closes the valve.
These valves are used to regulate water and steam in heating and cooling systems. A self-acting control valve's typical applications include:
Air compressors
Air chillers
Boilers
Industrial engines
Some of the advantages of self-acting valves include easy installation and enhanced durability. Plus, these valves are self-sufficient, meaning they don't need an external power supply to operate.
The primary function of all control valves is to regulate the flow, pressure, and temperature of fluids (and other substances). Additionally, control valves can regulate air, steam, glycol mixes, and chemicals based on predefined settings.
Control valves are found in any refining, chemical manufacturing, and other industrial applications. These valves are used for process quantities and consequential control. Now, how do these valves work?
Control valves regulate the flow in loops.
At the start of the loop, a transmitter and a controller compare the current flow level with the desired level.
The controller sends a correction signal to the control device (valve).
The control valve closes to reduce the fluid flow (or opens to increase it).
The valve opens or closes to ensure the desired level of flow.
You can find many control valve types and applications used in various industries. They include food & beverage, oil & gas, pipeline, biopharma, and many others.
As you understand by now, control valves are quite complicated mechanisms. It's not just about choosing the correct type of valve. To ensure you're getting the right valve for your system, you should also consider:
Media type. Your control valve should support the liquid or gas type. For example, metal works for pressure gasses, and corrosive materials require something like PFA or PTFE.
Actuation. Do you want a hand-operated valve or an actuator that turns it off automatically? On top of that, you should consider the positioning of the valve after it loses power. For instance, a double-acting actuator maintains the last position. In contrast, the spring return actuator either opens or closes the valve after losing the signal.
Installation. Consider your management system before choosing a valve. Some types of valves support remote monitoring and control, which can make maintenance much easier. Additionally, find out how easy it is to disconnect and reconnect the valve.
Maintenance. Some valves are virtually maintenance-free, and others require regular cleaning. Needless to say, some control valve types, like ball valves, are way easier to keep clean due to their design.
Now, the list isn't exhaustive. We recommend comparing control valves based on their advantages and disadvantages, functionality, efficiency, and price.
After reading this, you should have a good idea about control valve types and applications. We hope that our guide helps you get the best device for your tasks!
Feel free to check Blackhawk Supply for a great selection of high-grade control valves from reputable manufacturers like Belimo, Johnson Controls, Honeywell, and many others. Our shop has control systems, plumbing supplies, and a ton of other miscellaneous stuff!
Valve actuators can bring many benefits to an operation, including reduced maintenance costs, increased uptime and better safety. There are many more benefits and reasons why you should use an actuated valve, so continue reading our helpful guide to discover the top five reasons to invest.
The primary objective for an actuated valve is to move a valve into an open or closed position. It attaches to and works in conjunction with two parts: the valve pilot and the valve body.
As manufacturers crave for more productivity and efficiency, the need for actuated valves has become more important. Here are five reasons why you should use an actuated valve for your application:
Actuated valves allow for greater control and visibility of a system. If using a Programmable Logic Controller (PLC) or Distributed Control System (DCS) type system, it’s easy to communicate with valves and get a feedback signal to confirm that they’re in the position needed. When valves are manual, the door to operator error is left open.
The ability to remotely control a valve allows operators to stay safe. An actuated valve lets operators keep away from extreme hot and cold temperatures. It also allows them to stay clear of hostile environments, such as those with noxious gases.
In an emergency situation, an actuated valve goes into fail safe positions, whether that’s fail open or fail close. Pneumatic actuator valves will use a spring return, while an electric actuator valve has a back-up battery to allow for fail safe positioning.
A valve actuator takes one more thing off the mind of an operator when an emergency occurs.
When an actuator valve is involved, there are a great deal of cost-savings to be had for manufacturers. The operator is always in contact with the valve actuator. This ensures that the valve is open to just the right percentage, avoiding any wastage that would lead to an increase in costs.
When a valve is manually operated, there is a risk not only of wasted materials but of potentially ruined product due to manual operational errors.
Actuated valves are brilliant when valves can’t be easily reached manually. Whether that valve is located high above or down too low, if it’s actuated it can be remotely controlled.
This is another aspect of the safety that actuated valves can bring. It gives operators easier control of the valves and stops them from potentially risking injury by trying to control hard-to-reach valves.
Large valves can be difficult to close with a manual wheel, while fluid viscosity and velocity can have an impact on how much torque is needed to close the valve. Requiring operators to close large valves with manual wheels against rushing water is going to cost a lot of man hours and cause a decrease in productivity. It may also increase the risk of injury.
Setting up a valve with the appropriate valve actuators can make sure you have the right amount of force to turn or lift the valve every time.
Automation in the process industry is increasingly commonplace these days because actuators enable valves to operate with ease and reliability.
BM Engineering stocks quarter-turn actuators, which suit (but are not limited to) our ball valves and butterfly valves. We have the ability to add control and indication features, such as position feedback and Namur solenoid valves.
We also have in-house testing facilities for AS-i, Exi and 4-20mA control valves. Various other types of actuated valves are also available on request, such as angle seat valves, globe valves, diaphragm valves, 3-way valves, and electric actuated valves.
If you’d like to know more about the actuated valves we have at BM Engineering, don’t hesitate to contact us on 0141 762 0657 or email us at sales@bmengineering.co.uk.
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