What is a 2/2 normally open solenoid valve?

open solenoid valve

open solenoid valve : picture via eltra-trade.com

A 2/2 normally open solenoid valve is an electromechanical device used to control the flow of fluids, such as liquids and gases. It consists of a coil, plunger, and valve body. In its resting state, the valve opens, allowing fluid to pass through. When an electrical current is applied to the coil, the plunger is magnetically activated, closing the valve and stopping fluid flow.

Solenoid valves play a crucial role in various fluid control applications across industries. They provide precise and reliable fluid flow control, allowing for automation and remote operation. The ability to quickly open and close the valve in response to electrical signals makes them essential in process control systems, irrigation systems, pneumatic systems, and more. Their compact design, low power consumption, and versatility make them ideal for various industrial processes.

Working Principle of a 2/2 Normally Open Solenoid Valve

In a 2/2 normally open solenoid valve, the valve is open when no electrical current is applied to the coil. In this position, the fluid can flow through the valve freely. When an electrical current is sent to the coil, it generates a magnetic field, which attracts the plunger toward the valve seat. As a result, the valve closes, blocking the flow of fluid.

The solenoid coil is the primary component responsible for creating the magnetic field when energized. It is usually made of copper wire wound around a bobbin. When electric current passes through the coil, it generates a magnetic field.

The plunger, or armature, is a movable component within the coil. When the coil is energized, the magnetic field attracts the plunger toward the valve seat, causing it to close and stop fluid flow. When the coil is de-energized, the magnetic field dissipates, allowing the plunger to return to its resting position, and the valve opens, allowing fluid flow once again.

Industries and Systems Where These Valves are Commonly Used

2/2 normally open solenoid valves find extensive use in various industries and fluid control systems. Some key industries and applications include:

  1. Water Management: Used in water distribution systems, irrigation, and wastewater treatment.
  2. HVAC Systems: Employed in heating, ventilation, and air conditioning systems for fluid control.
  3. Automotive: Found in vehicle engine management systems and pneumatic controls.
  4. Medical Equipment: Utilized in medical devices and instruments for precise fluid control.
  5. Industrial Automation: Integrated into automated fluid handling and control processes.
  6. Food and Beverage: Used in dispensing, filling, and controlling fluid in production lines.

Specific Examples of Their Application and Advantages

  • Water Dispensing: In vending machines, the valve allows water to flow when a user selects a drink, enabling precise and controlled dispensing.
  • Pneumatic Actuators: In pneumatic systems, the valve controls compressed air flow to actuators, facilitating precise movement and control in manufacturing processes.
  • Heating Systems: In HVAC applications, the valve regulates the flow of hot water, ensuring proper temperature control and energy efficiency.
  • Medical Fluid Control: In medical equipment, the valve accurately regulates the flow of fluids for drug delivery and patient care, ensuring safety and precision.
  • Fluid Level Control: In industrial systems, the valve helps maintain fluid levels in tanks or reservoirs, preventing overflow or leakage.


  • Quick and responsive operation due to the solenoid’s fast switching capability.
  • Reliable and repeatable performance, ensuring consistent fluid control.
  • Compact and lightweight design, making them suitable for limited-space installations.
  • Low power consumption, contributing to energy efficiency in applications.
  • Versatile and compatible with various fluids, including liquids and gases.
  • The versatility and reliability of 2/2 normally open solenoid valves make them essential in various industries, providing precise fluid control and enhancing process efficiency.

Installation and Maintenance of 2/2 Normally Open Solenoid Valves

Proper Installation Guidelines for Optimal Performance

  • Positioning: Install the solenoid valve in the appropriate orientation to ensure the flow direction aligns with the system requirements.
  • Piping: Use suitable piping materials and sizes to minimize pressure drops and fluid restrictions.
  • Mounting: Securely mount the valve to prevent vibration or movement during operation.
  • Electrical Connections: Follow the manufacturer’s guidelines for proper electrical connections to the solenoid coil.
  • Environmental Considerations: Install the valve in a suitable environment, avoiding exposure to extreme temperatures or corrosive substances.

Routine Maintenance Tips and Troubleshooting Techniques

  • Regular Inspections: Conduct periodic inspections to check for any signs of wear, damage, or leakage.
  • Cleaning: Keep the valve and surrounding area clean to prevent debris from affecting the valve’s performance.
  • Lubrication: If required by the manufacturer, apply appropriate lubrication to moving parts to maintain smooth operation.
  • Valve Testing: Periodically test the valve to ensure it opens and closes as expected.
  • Troubleshooting: In case of any malfunction, refer to the manufacturer’s troubleshooting guide or seek professional assistance to identify and resolve the issue.

By following proper installation procedures and implementing routine maintenance practices, you can ensure the optimal performance and longevity of your 2/2 normally open solenoid valves, contributing to the efficient functioning of fluid control systems.

Comparison with Other Types of Solenoid Valves

Differentiating Features of Normally Open Solenoid Valves:

  • Operation: Normally open solenoid valves are designed to allow fluid flow in the de-energized state and block it when energized.
  • Flow Control: These valves provide full flow when de-energized, making them suitable for applications requiring immediate fluid passage.
  • Fail-Safe: In the event of power loss or system failure, normally open solenoid valves will remain open, ensuring continuous fluid flow.

Contrasting Them with Normally Closed and 3/2 Solenoid Valves:

  • Normally Closed Solenoid Valves: In contrast, normally closed solenoid valves block fluid flow when de-energized and allow it when energized. They are suitable for applications where fluid passage needs to be interrupted during power failure.
  • 3/2 Solenoid Valves: Unlike 2/2 solenoid valves, 3/2 valves have three ports and two positions. They can be normally closed or opened and include an additional exhaust port to redirect fluid flow.

When choosing between these solenoid valve types, consider the specific requirements of your fluid control application, including the desired flow control, system fail-safe measures, and compatibility with the overall system setup. Each type offers distinct advantages, and selecting the most suitable one will ensure the efficient and reliable operation in your application.


In this article, we explored the concept and functioning of 2/2 normally open solenoid valves. These valves are designed to allow fluid flow when de-energized, making them ideal for various fluid control applications.

2/2 normally, open solenoid valves are crucial in controlling fluid flow in industrial processes, automation systems, and other applications. Their fail-safe operation and quick response make them valuable components in systems where immediate fluid passage is essential.

Whether it’s for general fluid control or critical operations, these valves offer reliability, efficiency, and ease of use. Their versatility and compatibility with various media make them a preferred choice across industries.

In conclusion, understanding the working principle and applications of 2/2 normally open solenoid valves can help you make informed decisions when implementing fluid control solutions in your specific application scenarios. Always consider the system requirements and environmental factors to maximize the benefits of these valuable components in your setup.