Most of us interact with different pneumatic systems daily. Compressed air flowing through these systems facilitates the efficient operation of various processes, some of which have complex configurations and demand the utmost precision.

Achieving adequate air control in a pneumatic system requires investment in specialized control valves - to regulate flow rates, pressure and direction of the gaseous media. Pneumatic directional control valves are designed for such demanding applications, featured in industrial automation systems, HVAC units, movable and fixed machinery, chemical processing plants, automotive air braking systems, medical equipment and in aviation for landing gear operation and other aircraft actuation systems.

Why is understanding the working principles of pneumatic control valves necessary, and how can you utilize pneumatic solenoid valves to optimize the performance of airflow systems in different industries?

This article explores pneumatic solenoid valves in detail. It describes how pneumatic directional control valves work, the various configurations available on the market and their benefits. In the end, you will have all the necessary information needed to make a balanced and informed decision when choosing a valve for various airflow applications.

How Pneumatic Solenoid Valves Work

Pneumatic solenoid valves play a pivotal role in controlling the flow of compressed air or process gases. To understand their operation, let’s dive into their construction and the working principles that drive their functionality.

Components and Construction

A pneumatic solenoid valve is primarily made up of two components: electrical and mechanical. The combination of these components allows for precise directional control of gases.

• Electromechanical Device: This device, often comprising motors, switches, and other components, ensures the accurate regulation of the mechanical motion of machinery, cylinders, actuators, and other pneumatic components. It acts as a bridge between the electrical signals and the mechanical actions within the valve.
• Valve Body: The typical valve body features a solenoid, plunger, and several orifices, which vary based on the desired fluid control.

Operational Mechanics

The operation of a pneumatic solenoid valve revolves around the interaction between the solenoid and the plunger.

• Electromagnetic Induction: When an electric current is applied to the solenoid, it generates a magnetic force. This force influences the position of the plunger, which is connected to a seal. Depending on the plunger's position within the valve body, the seal either opens or closes the valve orifices.
• Airflow Regulation: When the orifices open, compressed air enters the valve compartment. This air provides the necessary actuation forces to alter the position of the flow control device, such as a spool or piston. This change in position directs or regulates the airflow through the pneumatic system.

Spooled Design and Functionality

Pneumatic solenoid valves have a spooled design.

• Design Features: The valve has a cylindrical internal body connected to various ports. The spool, which slides within this cylinder, contains seals along its length. Depending on its position, the spool can either open or close the valve ports, facilitating bi-directional flow.
• Electromagnetic Force: The spool's movement is influenced by a small force from the electromagnetic elements. While the electromagnetic force is the primary driver for moving the spool, the pressure of the working air can still play a role, especially under certain conditions or specific applications. However, in general scenarios, its influence on the force requirements is minimal.

De-energization and Return Mechanism

Once the solenoid is de-energized, the valve components revert to their default positions.

• Spring Mechanism: Some valves incorporate an additional mechanical element, like a spring, to maintain the flow control mechanisms in their default states. The solenoid must generate enough force to counteract the spring before allowing airflow into the valve body.
• Plunger Reset: The plunger returns to its default position when the electric current is either reversed or withdrawn. Depending on the configuration, this can close the valve orifices, stopping air from flowing to the valve body.

Electromagnetic Force and Its Variables

The force exerted by the solenoid to initiate flow actuation is influenced by several variables:

• Current Supply: The amount of current flowing into the solenoid is directly proportional to the electromagnetic forces.
• Solenoid Coil Design: Increasing the number of windings in a solenoid coil can amplify the magnetic flux, thereby enhancing the electromagnetic forces.

Solenoids for controlling the operation of pneumatic directional control valves can be direct-acting or pilot-operated. Pilot-operated pneumatic solenoid valves consume far less power compared to their direct-acting counterparts. Pilot-operated valves can utilize the pressure of the service fluid to actuate processes. The solenoid directly controls the pressure of the limited amount of air used to actuate the valves.

Specific Design and Usage Considerations

Pneumatic solenoid valves are designed for compressed air and gaseous media only. These valves have allowable leakage rates, which are safe when handling compressed air but consequential when dealing with liquid. Only use these valves in compressed air applications and pipelines.

Control Methods and Remote Monitoring

The operation of pneumatic solenoid valves can be controlled in various ways, depending on the specific configuration and complexity of an application. In some industries, these valves are configured to allow control using programmable logic controllers (PLC) or relays. These control methods allow process engineers to remotely monitor and operate valves, even in hardly accessible locations.

Benefits of Pneumatic Solenoid Valves

Pneumatic solenoid valves are indispensable flow control devices in compressed air and gas applications. These devices have compact and unique designs allowing them to regulate airflow faster and more precisely. Here is a detailed look into the benefits of these valves.

Precise Control

Pneumatic solenoid valves are preferred for their precision and quick responsiveness. This property is crucial when handling air, a compressible fluid that changes its physical properties in a short time. Pneumatic solenoid valves can respond to process changes, adjusting valve positions accordingly and facilitating seamless transitions in direction and flow rates of compressed air.

Pneumatic solenoid valves have quick response times thanks to the specialized valve designs, incorporating fast-acting solenoid valves and highly-responsive actuators. It means the pneumatic directional control valve can move from open to closed positions or inversely fast. Shorter response times mean the valves offer more predictable and dependable compressed air service.

One can configure the operation of pneumatic solenoid valves depending on the type of industrial application. These valves provide precise on-off air control, manage complex sequencing and process regulation, regulate proportional air control and promptly shut off airflow if required.

Precisely controlling the flow rate, direction and pressure of compressed air through pneumatic systems translates to better energy efficiency and can yield improved process performances since air is delivered in adequate quantities, as and when required.

Quick Responsiveness

Pneumatic solenoid valves facilitate fast and reliable regulation and control of compressed air and gases. Using electromagnetic forces to activate these valves means they can change states (open to closed or vice-versa) instantly. The fast responsiveness is because of the compact and lightweight designs of valves.

Internal valve components feature low moving masses. These lightweight masses minimize inertial forces within the valve body. It translates to lower energy losses, and the magnetic force delivered by the solenoid valve solely serves to manipulate the locations of the spool. These valves also feature short yet optimized airflow paths. Compressed air travels short distances whenever the valve orifices open or close while delivering the desired actuation forces. The shortened flow paths enhance the overall responsiveness of pneumatic solenoid valves to changes in process control signals.

Another aspect contributing to the faster responsiveness of pneumatic solenoid valves is the minimal friction and well-engineered component clearances between moving valve components. Lower frictional resistance means better valve efficiency, allowing it to respond better and faster to control signals. Designing a feedback system to monitor the positions of the pneumatic solenoid valve at different stages of operation can provide valuable insights for enhancing its responsiveness for diverse applications.

Durability and Reliability

Pneumatic solenoid valves can provide dependable, long-term compressed air service. These valves use high-quality fabrication materials to withstand aggressive industrial environments without losing their technical capabilities. The type of construction material is highly dependent on the valve application area, each selected to provide adequate resistance to corrosion by compressed air, operating environments and other fluids that may come in contact with the valves.

Pneumatic solenoid valves also have a limited number of moving parts. This simplified design reduces valve failure caused by mechanical wear and tear (friction between moving parts). These valves can operate for an extended time without requiring maintenance or component changes.

Pneumatic solenoid valves are designed to meet industry compliance standards, including the precise selection of sealing materials. Compliance with various industry standards means the valves can meet demanding industrial applications without leakages or susceptibility to damage by the service fluids. You can always extend the functional lives of pneumatic solenoid valves by practicing proper and regular valve maintenance.

Energy efficiency

Utilizing pneumatic solenoid valves for compressed air service is one way of addressing energy consumption challenges in facilities. These valves have several desirable features making them consume low energy when controlling or regulating air flow through pneumatic systems.

These valves use  solenoids, which require limited amounts of power to activate and manipulate the position of a plunger to actuate pneumatic components. The pneumatic solenoid valve uses an on-demand operation model. The solenoid only draws power when system requirements demand the opening or closing of a valve. The solenoid de-energizes upon achieving the desired flow control.

The fact that pneumatic solenoid valves have quicker responsiveness translates to shorter valve operating cycles. It implies the valves consume less power when operating, constituting improved energy savings.

Pneumatic solenoid valves are versatile and can be integrated with advanced control systems - PLCs or related distributed control systems. One can utilize these control systems to optimize pneumatic solenoid valve operating parameters, like on-off cycling and valve actuation sequences, optimizing energy efficiency.

Finally, these valves have limited (controlled) leakage rates. Regulating and preventing compressed air leakages around valves offers a sustainable means to reduce energy losses due to frequent pressure losses.

Safety

Pneumatic solenoid valves contain several features to reinforce the safety of processes, personnel, equipment and the environment. Some notable safety features are:

• Fail-safe mechanisms - They ensure the valves can maintain the safety of processes when there is a system power loss. The valves will move to a predetermined safety position, stopping further airflow.
• Lock-out tag-out feature - this is critical during valve maintenance intervals. This feature provides a method to isolate the pneumatic solenoid valve from the main power supply to prevent accidental activation of valves under maintenance.
• Manual override - some pneumatic solenoid valves have the manual override feature, allowing operators and maintenance technicians to operate valves without an electrical signal. This feature is vital during emergencies or scheduled maintenance intervals.

Types of Pneumatic Solenoid Valves

There are several types of pneumatic solenoid valves available on the market today. One should understand what each valve category does and how they are named before choosing a specific valve for an application. The designation of pneumatic solenoid valves is based on the number of ports, positions and ways of a valve. These valve positions and ports define the various functions that a valve can perform. Here is what each term means and applies to pneumatic solenoid valves.

• Ports - These are openings (orifices) or connection points available on the valve body. These openings can be inlets or outlets on the pneumatic solenoid valve, permitting compressed air (gaseous media) to flow through.
• Position - the position of a valve refers to the state of flow paths or passages. They determine how different compressed air flow paths connect or restrict flow. Specific valve positions permit air to flow through the pneumatic valve ports while others block the flow.
• Ways - These are existing flow directions or predefined paths that compressed air can follow when flowing through the pneumatic solenoid valves.

Let us explore the different pneumatic solenoid valves further and how they work.

2/2- Way Valve

2/2-way pneumatic solenoid valves have two ports and two positions. The two ports are an inlet or supply port and an outlet/exhaust port. The two ports provide entry and exit points from the pneumatic directional control valve, providing limited control of compressed air.

These valves have two positions, namely:

• Open position
• Closed position

The default position for 2/2-way pneumatic solenoid valves is closed. It means no compressed air can flow through it. Energizing the solenoid moves the pneumatic solenoid valve to an open position, allowing air to flow.

2/2-way pneumatic valves are essential for on-off compressed air flow. They start or stop the flow of gaseous media.

A typical example of a 2/2-way pneumatic solenoid valve is the actuation of pneumatic equipment. Such valves can accurately control the movement of a pneumatic gripper. Blocking or allowing gases to flow through the pneumatic solenoid valve causes the gripper to open and close, picking and dropping materials as required.

3/2-Way Valve

It refers to a valve containing three ports and two valve positions. The three ports in such a pneumatic valve configuration are:

• Inlet or supply port
• Outlet or exhaust port
• Working port

One of the ports is designated as a common port and connected to the other two ports at different instances, permitting or blocking the flow of compressed air through the process valve.

3/2-way valves have two positions; Normally open (NO) and Normally closed (NC). In the NO position, the common port connects to the working port. The configuration allows compressed air to flow through the process valve unless the solenoid is activated. Activating the solenoid blocks the flow of air. For a normally closed 3/2-way valve, the common port connects to the exhaust port. Gases and compressed air will only flow when the solenoid is activated.

3/2-way pneumatic solenoid valves are indispensable for controlling the movement of single-acting cylinders or pneumatic actuators. Energizing the solenoid for valves in such applications permits airflow into the cylinder, extending the actuator. Withdrawing power to the solenoid blocks the airflow, causing the pneumatic actuator to retract.

5/2-Way Valve

This type of pneumatic solenoid valve contains five-valve ports and two positions. The five ports are:

• Two exhaust ports
• Two working ports
• One inlet/supply port

The working ports connect directly to actuators or components of a compressed air system. The exhaust ports release or expel compressed air from the system when required.

The two positions of a 5/2-way pneumatic solenoid valve are the normally closed (NC) and normally open (NO) configurations. In a normally closed position, one working port connects to the exhaust port. The second working port connects to the common port. This configuration blocks airflow through the system unless the solenoid is activated.

Activating a normally closed configuration causes the pneumatic solenoid valve to adopt the normally open position. The connections mentioned above reverse, consequently permitting compressed air to flow through the pneumatic solenoid valve. As this air moves, it causes instant actuation of subsequent processes and equipment.

5/2-way pneumatic solenoid valves are common for actuating double-acting pneumatic cylinders in machinery and industrial processes.

5/3-Way Valve

Valves in this category have five ports and three positions namely:

• Normally closed
• Normally open
• Center position

The five ports of these valves include two exhaust, two working and a single common (inlet/supply) port.

When the pneumatic solenoid valve is at the center position, airflow is restricted. All five-valve ports remain closed. In the normally closed configuration, the common port connects to one of the working ports. The second working port connects to one of the exhaust ports. This arrangement allows air to flow from one working port to the other.

Energizing the solenoid keeps the valve in a normally open position. The above connections change, connecting the common port and the opposite (second working port). Compressed air flows from the common port to the second/opposite working port. It will also cause the other working port to exhaust via one of the exhaust ports.

5/3-way pneumatic solenoid valves are common in automated machining processes for indexing workpieces, enabling precise positioning of parts during production.

Choosing the right pneumatic solenoid valve for your application

We now understand how pneumatic solenoid valves work and their different configurations. Choosing the correct type and size of pneumatic solenoid valve for your specific application is vital for ensuring durable, dependable and optimized performances of your pneumatic systems. Here are a few tips to ensure you select the correct devices.

• Explore the desired compressed air flow requirements. Evaluate variables like the required flow rates, process temperature and other environmental conditions. It will ensure you choose a valve fabricated from the correct set of materials to withstand harsh operating conditions and supply compressed air in adequate quantities.
• Ensure material compatibility. Before selecting a valve, it's crucial to ensure that the material of the valve is compatible with the substances flowing through the system. Incompatibilities can lead to corrosion, leaks, and other issues that can compromise the system's safety and efficiency. Refer to our chemical and material compatibility database for guidance.
• Evaluate the desired functionality of the pneumatic solenoid valve. That way, you can select the valve with the correct configuration to ensure seamless regulation and directional control of compressed air.
• Determine the required safety features and choose one compatible with your processes.
• Check if the pneumatic solenoid valve is compatible with existing automation systems. Choose a valve compatible with your automation systems for easy installation, integration and stress-free operation.
• Regularly maintain and inspect pneumatic solenoid valves. Be sure to check for signs of wear and tear. Pay attention to safety measures when maintaining these valves.

ElectricSolenoidValves.com stocks a range of pneumatic solenoid valves to suit different industrial and domestic applications. Our team of valve experts is available to assist you through the selection, installation and operation of these pneumatic directional valves based on your processes and automation requirements. You can also inquire about our pneumatic solenoid valve lines through our website and other communication channels. Feel free to reach us and shop for the best, high-quality pneumatic solenoid valves today.

Final Words

Pneumatic solenoid valves are critical in industrial applications and processes using compressed air. These valves are available in different configurations and sizes, ensuring customers with different needs meet their compressed air flow and regulation requirements. These valves are advantageous, given their quick responsiveness, compact designs and impeccable safety standards. You can utilize these valves to automate various compressed air applications without worrying over skyrocketing energy costs because they are efficient, sustainable, reliable and durable.