Find the Right Pneumatic Valve for Optimal System Performance
Choosing the right pneumatic valve is critical for system efficiency, reliability and safety. As an experienced pneumatic systems partner, JHFOSTER provides tailored solutions and expert guidance to help you select the most effective valve for your application.
What is a Pneumatic Directional Control Valve?
A pneumatic directional control valve is a component that controls the direction of compressed air in a pneumatic system. They can be classified by internal design. Two of the most common are:
Spool valves: These are often used in automation systems to direct the flow of compressed air to pneumatic cylinders, motors and other actuators. The design includes a machined spool inside the valve body that moves to create or block flow paths through ports, controlling air direction for precise, repeatable motion.
Poppet valves: Poppet valves include a disk-shaped plug, or poppet, that moves against a circular opening (the seat) to control the flow, enabling tight seals, fast responses and a rugged design, making them suitable for industrial applications. They can handle poor quality compressed air without issues.
Valves of either design can be used in harsh environments when the appropriate Ingress Protection (IP) rating is chosen.
Understanding Actuation Methods
Pneumatic directional control valves are also categorized by how they are actuated.
Solenoid-Operated Valves
Controlled by an electric signal, there are two types of pneumatic solenoid valves:
Direct-acting solenoid: These convert electrical energy into magnetic energy, directly operating the spool or poppet to control flow direction through the valve ports. The valve will assume the position corresponding to the electrical signal, regardless of the input pressure applied. No minimum pressure is required.
Solenoid Pilot Operated: Commonly used in many pneumatic applications, solenoid pilot operated valves rely on pilot pressure to shift the spool or poppet to control flow direction. They are energy efficient due to their ability to operate using smaller solenoids, but a minimum pilot pressure is required.
Air-Operated (Pilot) Valves
Controlled by air pressure rather than electricity, air-operated pilot valves are suitable for use in hazardous environments or where electricity is not available.
Mechanical and Manual Valves
Operated by direct mechanical or manual contact, such as levers, pedals and buttons, mechanical and manual valves are used in safety devices, limit switches and manually operated gates and presses.
Valve Configurations: Ports, Positions and States
The name directional control valve is often used interchangeably with pneumatic valves because they control the direction of the flow (or may stop it entirely). Pneumatic valves come in multiple port configurations with each port, or way, assigned a specific function. For example, a three-way directional control valve will have one port connected to the pressurized airflow, another port connected to the actuator and a third port for exhaust.
2-Way, 3-Way and 4-Way Valves
- 2-Way: These offer one inlet and one outlet to allow or stop flow.
- 3-Way: 3-way valves contain an additional exhaust port to vent pressure from the outlet when the inlet is blocked.
- 4-Way: With one inlet, one exhaust, and two outlet ports, 4-way valves are commonly used to control double-acting cylinders.
4-Way 5-Port Valves: The Standard for Actuator Control
Five-port valves are an evolution of 4-way valves, typically with one pressure inlet, two outlets to the device and two exhaust ports.
- 5/2 Configuration: This configuration offers five ports and two positions, such as extend and retract.
- 5/3 Configuration: This configuration has five ports and three positions. The third or center position (all ports blocked, center exhaust, center pressure) permits an actuator to stop mid-stroke.
Spring Return vs. Detent Valves
- Spring Return: Sometimes called spring offset, or monostable, are two position valves that have only one active position, which is maintained by the control signal – either electric, pneumatic, mechanical or manual. When the control signal is removed, an internal spring returns the valve to its designated rest position (which may be open or closed, depending on specifications).
- Detent: Remain in their last actuated state when the control signal – electric, pneumatic, mechanical or manual – is removed.
7 Key Factors for Selecting the Right Pneumatic Valves
Selecting the best pneumatic valve for your application is critical to its performance, efficiency and reliability. Here are seven basic considerations for valve selection:
- Media: Is the valve controlling gas or liquid flow and of what composition, temperature and pressure is the media?
- Flow Capacity (Cv): What flow rate is required to operate the downstream component within a specified time?
- Valve Configuration: How many ways/ports and positions are needed for your application?
- Actuation: Will solenoid, solenoid pilot, air-piloted, mechanical or manual operation be most suitable?
- Environment: What are the operating conditions? Will the application be subjected to washdowns? Are hazards present? Are there other environmental factors that necessitate a special design or IP rating?
- Safety: How will the valve function during an E-Stop event?
- Return Method: Does the valve need to return to its resting position (spring return valves) or remain in its last actuated state (detent or latching valves) if the control signal is interrupted.
Your Partner in Pneumatic System Optimization
Navigating all the options for pneumatic valves can be complex and confusing, but partnering with JHFOSTER ensures that you find the most reliable, efficient and cost-effective valve for your application. Contact us today to speak with a pneumatic systems expert. Have a specific valve in mind? Request a quote today.
