Control valves are the unsung heroes of many industries, acting as the precise hands that regulate critical process variables like pressure, temperature, and flow. But just like a skilled craftsman needs the right tools, a control valve often requires a range of accessories to truly excel. While the valve is vital, it's these complementary components that enhance their functionality, improve control accuracy, and meet specific application requirements.
In this post, part of our "Control Valves 101" series, we will explore some of the most common control valve accessories, their functions, and the benefits they offer. Disclaimer: actuators come up a lot—if you're not familiar with the terms already, check out our actuator glossary to get up to speed before proceeding.
The air filter/regulator screens out impurities from the power supply medium, usually compressed air. This prevents potential contamination of the actuation system, positioner, or other accessories.
This device regulates or limits the air supply pressure to the actuator, ensuring consistent performance. By mounting the air filter/regulator between the power source and the actuator or positioner, the system maintains operational integrity and avoids performance degradation due to contaminants.
When you need to monitor the open, closed, or midstroke position of a valve or actuator, a limit switch is used to send a follow-up signal that confirms the current position. This electrical switching device is crucial for triggering alarms, operating signal lights, or activating electric relays or small solenoid valves based on the valve's position. By providing this critical position feedback, limit switches ensure that control systems operate safely and efficiently, allowing for timely interventions if needed.
In hazardous or hard-to-reach locations where a mechanical connection between the limit switch and the valve stem or actuator shaft is impractical, a proximity switch serves as an effective alternative. Unlike a traditional limit switch, a proximity switch uses a magnetic sensor to detect position, eliminating the need for physical contact. This makes proximity switches ideal for environments where direct mechanical connections are undesirable.
A position transmitter is an accessory that provides a continuous signal reflecting the exact position of the valve or actuator. This information is crucial for monitoring performance or integrating with other control systems. By delivering real-time position feedback, position transmitters enable precise control and enhance the overall reliability of the process control system.
For larger pneumatic actuators that struggle to achieve fast stroking speeds due to their larger air chamber volumes, a flow booster is an indispensable accessory. Flow boosters accelerate the stroking speed by increasing the volume of air supplied to the actuator, ensuring that even large actuators can respond quickly to control signals. This accessory is particularly important in processes where speed and responsiveness are a priority, such as emergency shutdown systems, rapid valve adjustments in chemical processing, or high-speed flow control in automated manufacturing lines.
The solenoid is an electrical control device that channels signals from the control system to the actuator or, in some configurations, to the valve positioner. By controlling the flow of air or fluid, the solenoid enables precise and timely valve adjustments, ensuring accurate system performance.
Upon receiving an electrical signal—typically in the range of 4 to 20 mA—the solenoid channels air supply directly to the actuator. This accessory is crucial for automating the control valve, enabling rapid and precise responses to control signals.
Safety relief valves protect the system from overpressurization by opening to the atmosphere when the pressure exceeds a preset threshold. These valves become especially important when you use high-pressure actuators or volume tanks. In such scenarios, local codes — safety requirements established by local government authorities or industry-specific regulatory bodies —- may mandate the use of safety relief valves to prevent potential damage or hazards, such as pollution or equipment damage, associated with overpressurization.
To manage the stroking speed of an actuator, you use a speed control valve. This accessory restricts the amount of air flowing to or from the actuator, allowing precise control over the actuator’s speed. Typically, you mount these small valves between the tubing and the actuator, and they come in sizes that match standard tubing dimensions. This makes them versatile and easy to integrate into existing systems.
Each of these accessories plays a key role in ensuring that control valves operate efficiently and reliably within a process system. The diverse range of control valve accessories underscores the importance of precision and customization in process control. At Trimteck, we believe that every detail matters, and that’s why we offer bespoke, precision-engineered solutions tailored to your application's unique demands.
If you're looking to optimize your control valve setup with the right accessories, the Trimteck team is here to assist. Our experts can help you select the best components to enhance your system's performance and reliability. Contact us today to learn more about how we can support your process control needs.