Control valves

Which control valve will fit my application?

All types of commercially available industrial control valves are designed for their specific application, depending on, for example, media type, temperature range, pressure range and flow range. For simpler applications, traditional shut-off valves such as butterfly valves and ball valves are suitable. For more demanding applications where there is a risk of erosion, cavitation and high noise, a ball sector valve is preferred.

There are no control valves that are suitable for all applications – so consult a specialist for advice on which type of control valve, actuator and positioner will provide the lowest total life cycle cost in your process.

Feel free to contact us for help finding the right control valve for your application. You can also book a meeting directly with one of our product specialists.

Different functions of control valves 

Control valves can be either manual or automatic. Manual valves require an operator to physically adjust the valve to change flow or pressure. These are simple and cost-effective but require continuous monitoring. Automatic valves use sensors and controllers to adjust the valve based on preset parameters, making them ideal for complex and large-scale systems where continuous control and monitoring are necessary.

Control valves are essential for ensuring safe and efficient operation of industrial processes. Their various types and functions make them adaptable to a wide range of applications. Whether it's temperature regulation, pressure control, or flow regulation, there is a control valve suitable for each task.

To select the most suitable control valve for specific needs and applications, it is important to carefully consider several factors. These include the specific requirements of the application, type of medium (liquid or gas), pressure and temperature conditions, as well as the valve's capacity and responsiveness. By doing so, one can ensure both efficiency and safety in the system.

Temperature control valves

Control valves for temperature regulation control the temperature within a system by adjusting the flow of cooling or heating. Mixing valves and temperature control valves can be adjusted automatically to maintain a stable temperature.

Control valves for temperature regulation are critical components in heating systems, ensuring a consistent temperature in various processes and applications. These valves regulate the flow of heat, such as hot water or steam, to maintain a constant temperature.

Maintaining a stable temperature is crucial to ensure optimal performance and safety. In industrial settings, temperature variations can adversely affect product quality or processes.

Pressure control valves

Control valves for pressure regulation are crucial components in systems handling liquids, gases, and steam. Pressure control valves, particularly for steam, play a significant role. Steam is commonly used in industrial processes for heating, sterilization, and power generation. Excessive steam pressure can lead to dangerous situations such as pipe bursts and equipment damage. Therefore, it's essential to control and reduce pressure when necessary.

In summary, pressure control valves are essential for managing steam pressure in various applications, ensuring safe and efficient system operation.

Flow control valves 

Control valves for flow regulation control the amount of liquid or gas, including water, passing through a system, crucial for maintaining efficiency and safety in many processes.

They are often used to adjust flow to maintain a desired volume or ensure processes receive precisely the right amount passing through a system. Two common types of flow control valves are ball valves and butterfly valves. Ball valves provide simple and quick shut-off and flow regulation, while butterfly valves are effective for regulating large volumes with minimal pressure loss.

Factors such as valve material, pressure and temperature resistance, as well as the valve's capacity and responsiveness, are crucial considerations. Choosing the right valve ensures efficient system operation and minimizes maintenance needs.

How control valves work

Control valves are usually opened and closed using electric, hydraulic, or pneumatic actuators. Electric actuators utilize electric motors for precise flow control and remote operation. Hydraulic actuators use fluid pressure for high power in applications with high pressures or large flows. Pneumatic actuators use compressed air for rapid and reliable operation, suitable for applications requiring quick response and safety.

The valve position is determined by an input signal, typically 4–20 mA, where 4 mA corresponds to a closed valve and 20 mA corresponds to a fully open valve. Any value between 4 to 20 mA is corresponding to a mechanical position, degrees for rotary valves and lift in mm for linear valves. In most cases a positioner with an internal control loop is used i.e. the mechanical position is continuously sensed and compared to the input set value, allowing the positioner to set the lift angle.

Which valves are best suited as control valves?

When it comes to choosing which valves are best suited as control valves, there are several factors to consider, including the specific requirements of the application, type of medium (liquid or gas), and pressure and temperature conditions. The application's demands for flow accuracy and control must also be taken into account, as some valves offer finer adjustments than others.

Maintenance and lifespan are also important factors, as valves with low maintenance requirements and long lifespans are more cost-effective in the long run, especially in demanding environments. By carefully considering these aspects, one can select the most appropriate control valve for specific needs and applications, ensuring both efficiency and safety in the system.

Seat and globe valves are excellent as control valves due to their outstanding flow control and precision, making them ideal for applications requiring precise flow regulation. Ball valves can also be used as control valves in systems where quick shut-off and reliable sealing are needed, although they are not as precise as seat valves. Butterfly valves are suitable for large flows and low pressures but lack precision compared to seat valves. Gate valves and check valves are less suitable as control valves because they do not provide linear flow control and are not designed for flow regulation.

The difference between self-acting valves and control valves

Self-acting valves

Self-acting valves operate without the need for an external power source. They rely on the process fluid’s pressure or flow to function automatically. These valves are commonly used for temperature control in heating systems, hot water circulation systems, and other applications where maintaining a constant flow is essential.

Advantages: Simplicity and reliability: Fewer parts and no need for external control systems.

Disadvantages: Less precise control: Their functionality is limited to the mechanical properties of the fluid.

Control Valves

Control valves are more complex and are used for precise flow control of liquids or gases. They can be adjusted manually or automatically. Control valves are commonly used in the process industry, HVAC systems, water and wastewater treatment, power plants, and other engineering systems.

Advantages: Precise control and suitable for a wide range of applications

Disadvantages: Require more maintenance and monitoring.

Cavitation issues, noise problems, and wear

Cavitation issues

Cavitation occurs when the pressure in a liquid drops low enough for the liquid to turn into vapor. This creates bubbles that collapse in areas of higher pressure, causing damage to valves and surrounding equipment. Cavitation can lead to erosion, vibrations, noise, and a shortened valve lifespan. To prevent cavitation, it's crucial to properly size the valve, reduce the pressure drop across it, and use specially designed cavitation-resistant valves.

Noise problems

Noise issues in valves can result from turbulence, cavitation, or rapid pressure changes, which can disrupt the work environment. Excessive noise can cause discomfort, stress, and even hearing damage for operators. Selecting the right type of valve, using sound-absorbing materials, and optimizing flow conditions can help reduce noise levels.

Wear and lifespan

Valves are subjected to friction, corrosion, and mechanical stress over time, leading to wear and reduced lifespan. Wear can result in leakage, decreased performance, and expensive repairs. Regular maintenance, corrosion protection, and using durable materials can extend the lifespan of valves.

Understanding these factors and choosing the right valve type, along with implementing appropriate measures, is essential for ensuring the efficient and reliable operation of industrial systems.

Sizing and selection

Get help with the dimensioning and calculation of control valves with our Ramén PRO Sizing calculation tool. Here you can find the control valve that best suits your process by entering your unique parameters. The software then suggests the best option for your application. Our experts at Ramén Valves are available to help with control valve calculations if you need it. You can book an appointment with us to get help. With our support, you can ensure that your control valves are correctly dimensioned.

Our control valves

Ramén Valves offers a wide range of control valves of the type; Ball Sector Valves, Eccentric Rotary Plug Valves, Microflow Globe Valves, and globe style control valves.

Ball Sector Valves

Our in-house manufactured Ramén Ball Sector Valve consists of a ball sector with an elliptical to circular opening, which provides high resolution and equal percentage control characteristics in the most demanding control applications. Ramén Ball Sector Valve has been designed as a control valve for liquids, gases, steam, media abrasive particles, sludge, abrasive slurry, powder, pellets, and viscous media. The design is well proven in a variety of process industries since the 1950s. This type of valve can also be called a segment valve. Read more about our ball sector valves.

Eccentric Rotary Plug Valves

Eccentric rotary plug valves use a cam like motion to move the plug into the seat, thereby effecting closure. There are several advantages to this type of valve. There is less torque on the plug once it breaks free of the seat as it is no longer in contact with the seat. Since there is no contact between plug and seat, eccentric rotary plug valves will not exhibit the wear normally seen with a ball valve, whose plug is in constant contact with the seat during operation. Ramén Valves offers eccentric rotary plug valves from the American manufacturer Cashco Inc. Read more about our eccentric rotary plug valves.

Microflow globe valves

Microflow globe valves are small control valves designed for pilot plant and research applications. They are suitable for control of low flow applications in all types of process industries. Per definition in EN60534, microflow valves are valves with a Cv > 0,05. Ramén Valves supply a wide range of microflow valves from the American brand Badger Meter. Learn more about our microflow globe valves.

Globe style control valves

Globe style control valves are the most common type of control valve. They got their name because in the early design of the valve the interior cavity of the valve had a circular or globe shape. Globe valves are also known as Linear Valves because the stem that actuates the valve moves up and down in a straight line. Learn more about our globe style control valves.