Valve Terminals Complete Guide: Types, Applications, and Selection

What Are Valve Terminals and How Do They Work?

Definition and Actuation Mechanism

Fundamentally, a valve terminal is a centralized device that manages the supply of compressed air to various industrial components. It can provide a controlled supply to 30 (expandable up to 128+) pneumatic based devices using solenoid coils on each port that act as gatekeepers. Once these solenoid coils receive a command from a computational device, they open to direct compressed air through the designated port in a controlled manner.

There can be conditions in which the pressure downstream of the solenoid is too high or too low (vacuum), which can hinder the solenoid's performance. In such cases, a pilot valve with a smaller secondary air supply assists in its movement regardless of the load.

Power Amplification and Smart Networking

In simple terms, valve terminals are devices that convert a digital signal to a massive physical force. A single data packet sent from a computational device can trigger the opening of the valve or actuate a car crusher. Each port can deliver over 30,000+ liters of compressed air per hour. They act as a vital connection between software and industrial scale components. They are not just a mechanical device, but also a computer node in the factory network.

Traditionally, a web of wires sent data to valve terminals for actuation. Technologically advanced valve terminals use a single network wire from the PLC to tell the valve terminal exactly which port to activate. Moreover, the modern CANopen protocols have enabled the terminal to talk back to the main computer. If a valve jams or pressure drops, the terminal instantly flags the exact error over the network, saving hours of troubleshooting.

Types of Valve Terminals In The Market

We can categorize valve terminals into three major categories based on their market presence. For extreme and unique applications, there are also specialized types that cannot be placed in the three major categories. Therefore, we will mention them separately:

By Communication System

These are the types defined based on the way they receive orders from the PLC to move solenoids.

• Multipole: These are the traditional valve terminals that require an individual signal cable for activation of the port. These become bulky, provide limited ports, and are incapable of sending back data.

• Fieldbus / Industrial Ethernet: Instead of individual valve wires, these utilize a single Ethernet cable connection to the valve terminal. It can communicate data to handle complex commands, monitor system health, and integrate into massive plant networks.

• IO-Link: It is the first globally standardized IO technology (IEC 61131-9) for communication with sensors and actuators. It is part of Industry 4.0, allowing operators to adjust settings and read sensor data for predictive maintenance.

• Integrated Control: Instead of a central master controller, these valve terminals have a built-in PLC that can run a standalone machine all by itself.

By Physical Configuration

• Modular: These allow attachments to valve terminals with solenoid valves, expanding the number of ports. These are ideal for systems that are expected to grow with time.

• Compact: These come with a fixed number of ports and have compact dimensions suitable for applications where durability is key.

• Valve Plate: These feature custom machined plates to provide air in a highly specialized manner for a particular machine.

By Valve Functionality

In pneumatic systems, the valves are named by the number of air connections (ports) and switching states (positions).

• 5/2 Way: This valve has 5 ports and 2 positions. These can push a pneumatic cylinder out and return it to its original position using compressed air.

• 3/2 Way: This valve has 3 ports and 2 positions. It is for simplified cylinders featuring a spring force for returning to the original position. It only pushes air into the cylinder and vents it out.

• 5/3 Way: It is an improved version of the 5/2 way valve with the option to stop a cylinder mid-position. If the power of air is lost, the valve shifts to the center position, locking the cylinder mid-stroke for safety.

• Mixed: A single valve terminal can feature a combination of the valves listed above.

Specialized Types

• Explosion-proof (ATEX): Designed with precision so that there is no spark in solenoids in a highly flammable environment. 

• Hygienic: These are made using stainless steel for hygienic applications. These are FDA approved and can handle the high chemical washdowns required in food and pharma applications.

• Safety-certified: For human interactions, these features have a fail-safe position for safety.

Main Components of a Valve Terminal

There are three major layers to the valve terminal design. All of them collectively make it possible to direct air on a digital or electrical command.

Physical Foundation

• Base Plate: It is the main housing that has grooves to distribute common supply air to all valves and collect exhaust air.

• End Plates and Tie Rod: These hold the main supply port for the primary air supply and vents. They also keep the modular components together by forcing them together using stressed tie rods.

• Seals and Springs: The seals are made using NBR (Nitrile) or Viton, ensuring that the system remains leak proof internally and externally. Springs provide a mechanical fail-safe to neutral position in case of power loss.

• Silencers: These reduce the deafening noise in high pressure systems when technicians exhaust air for testing purposes.

Actuation and Control Core

• Solenoid Valves: These use electromagnetic force to open or close the air path. These can be piston or poppet type.

• Pressure Regulators and Sensors: These allow regulation of pressure downstream of the valve terminal. It can provide 6 bar high pressure for heavy lift and reduce pressure to 2 bar for delicate grippers while the supply compressed air pressure remains the same.

• Electrical Control Systems: This is the interface. It ranges from a simple Multi-pin connector to Fieldbus/IO-Link modules.

Advanced Intelligence

• Integrated ASICs: It embeds application specific integrated circuits directly onto the valve terminal.

• Embedded Vision and Optical Feedback: Some modern terminals can integrate with vision sensors to ensure a part is actually present before firing the pneumatic actuator. It prevents dry fires and reduces waste.

Advantages And Benefits of Valve Terminals In Industrial Pneumatic Systems

Space Optimization and Cost Efficiency

Modern industries require compact designs for efficient machinery layouts. Valve terminals consolidate multiple valves into one unit. The result is a 70% reduction in installation footprint. It also cuts installation time by 60% and halves I/O expenses by minimizing wiring and tubing.

Flexibility and Reliability

The modern valve terminals come with hot swapping options. It means there is no need for a shutdown to perform replacement, and more ports can be added to the system. Integration of diagnostics, such as failure LED indication and reduction of connection points, reduces the chances of failure and downtime by 35%.

Performance Enhancement and Sustainability

Using valve terminals instead of a centralized control system reduces the air paths to the components. Shorter air paths translate to faster response times and up to 50% energy savings. The modern solenoids also use low-power coils and optimized cycles to lower the overall carbon footprint.

Scalability and Modular Design

A single valve terminal can manage up to 128 valves or 512 I/O points for complex cell control. Along with its ability to add, remove, or replace a number of ports through modular design, these terminals are highly versatile and in line with modern, efficient systems.

Simplified Maintenance

These devices feature centralized access. It means that the technician has to access one location to perform the task instead of going through a web of nodes to pinpoint the equipment failure. Moreover, their IP65/67 ratings make these valve terminals specifically engineered to withstand dust, water jets, and coolant exposure in demanding industrial settings. durability in harsh

Advanced Features

The premium industrial grade valve terminals come with soft stop technology. These are servopneumatic features that can slash cycle times by 30% while protecting actuators from mechanical shock. Their high-end terminals now utilize anti-cavitation trims to prevent internal erosion during high-pressure drops, significantly extending service life in extreme conditions.

Key Application of Valve Terminals

Valve Terminals Selection Guide

If you are looking for a valve terminal and require a standardized process to find the right specifications for your project, then you are in the right section. Here is a practical, ready to print and use checklist based on engineering requirements:

Technical Parameters

[   ] Total Flow Rate: Calculate the flow rate requirement in case all the valves operate simultaneously. These are calculated in CFM/LPM.

[   ] Safety Margin: Add 20 to 30% extra margin in flowrate to account for inaccuracies.

[   ] Pressure: Check the compressor supply pressure range and actuator requirements. Match them with the valve terminal you are aiming to purchase.

[   ] Response Time: Check if the response time is suitable for your system.

Control and Communication

[   ] Network Protocol: What communication method is compatible with your current system? Is it multipole for basic setups, or Fieldbus/IO-Link for advanced PLCs?

[   ] Count I/O Nodes: Does the valve terminal support the input/output capacity for all current coils and sensors?

[   ] Diagnostics: Is your current system equipped with the necessary software and hardware to provide real-time fault feedback to the main controller?

Environmental and Durability

[   ] IP Rating: Do you require ingress protection against dust and water?

[   ] Climate Variables: Does the valve terminal suit your climate change variables, for example, coastal or middle of desert operations?

[   ] Vibration Resistance: Will the terminal be subjected to vibrations? If the platform is expected to vibrate, then ensure that it offers smooth operation under your field conditions.

Configuration and Functions

[   ] Choose Physical Layout: Have you selected the right build type, like compact for tight spaces, or modular for future expandability?

[   ] Match Valve Types: Do the number of ports and positions match your requirement?

Conclusion

Almost all modern industries use pneumatic air to initiate movement in various equipment. They require a centralized unit that controls compressed air to change the state of machinery. Using air for actuation is safe for various industries like food, where hygiene is vital, or pharma, where oil can contaminate medicine. These devices offer efficiency, reliability, and versatility across diverse industries. By understanding their types, components, advantages, and applications, users can optimize systems for enhanced performance and reduced costs.

For flawless integration and continuous operations of the manufacturing process, you need to select the right valve terminal. Follow our checklist for selection and find the matching valve terminals from Titan-Automation. They offer high-performance valve terminals tailored for smart automation. 

Visit https://www.titan-automation.com/valve-terminal.html for more information.

FAQs

Q1. What are valve terminals, and why use them instead of standalone valves?

It is a centralized command hub for all your pneumatic devices. It combines multiple solenoid valves into a single unit. It saves space, lowers installation times, and drastically reduces wiring. They shorten the air path by installation in close proximity, making the entire system efficient.

Q2. Where can valve terminals be safely utilized?

Valve terminals are highly versatile equipment that can work under vacuum conditions as well as in hazardous environments. They utilize pilot valves for managing vacuum operations and specialized enclosures that support IP67 ratings for heavy washdowns and ATEX certifications for safe operation in explosive zones.

Q3. How do you select the right valve terminal and maintain the right system?

Choosing the right terminal comes down to balancing four key factors: your required air flow, the necessary communication protocols (like Fieldbus or IO-Link), the physical environmental conditions, and your project budget. Once installed, maintenance is highly streamlined; it primarily involves utilizing the terminal's built-in digital diagnostics to catch faults early, alongside routine physical checks for air leaks or standard component wear.