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Solenoid valves are among the most widely used types of valves today. They come in various forms designed to control the flow of water, gas, and other fluids. In this article, we will explain what a 2-way solenoid valve is and how it operates. Additionally, we will explore the differences between normally open and normally closed solenoid valves.
A solenoid valve is an electrically controlled valve that regulates the flow of liquids or gases. Like other types of valves, it is commonly used to control the movement of fluids in a system.
A typical solenoid valve consists of a valve body and a solenoid coil mounted on top. The solenoid contains wires that carry an electric current, and the valve itself is positioned below the coil. Valves can be installed in various orientations to suit different applications.
Designs may vary depending on the manufacturer, as well as between 2-way and 3-way valves. A 3-way valve includes an additional exhaust port.
The simplest form is a directly operated solenoid valve. In this design, the solenoid is primarily a coil of wire. When an electric current flows through the coil, it generates an electromagnetic field that moves the valve.
Depending on the type of solenoid valve—normally open or normally closed—the valve will open or close in response to the electric current. The difference between normally open and normally closed valves will be explained later in this article.
Solenoid valves offer several key advantages:
Low power consumption
Remote operation and automation capability
Easy and inexpensive replacement parts
Compatibility with both low and high temperatures
Can be installed horizontally or vertically
Versatile for use in a wide range of machinery and applications
Automated sprinkler systems are a common application of solenoid valves in home and garden setups. Whether controlled by a timer or a smart home system, the solenoid valves regulate water flow.
When the valves are off, the irrigation system prevents water from flowing. Activating the valves allows water to pass through, watering lawns, gardens, or other outdoor plants. Multiple solenoid valves can be used in the system to control water flow to different zones individually.
A 2-way normally closed solenoid valve has two connected ports: an inlet, often called the cavity port, and an outlet, referred to as the orifice port.
The valve is controlled by an electric current passing through the solenoid. When the valve is energized, the plunger lifts, allowing liquid or gas to flow from the inlet through the valve and out the outlet.
When the power is turned off, the plunger returns to its original position, pressing against the orifice to stop the flow.
In detail, when the valve is de-energized, the plunger is pushed downward by a spring or similar mechanism, sealing the orifice. Pressurized fluid enters the valve cavity but cannot pass through. Once electric current energizes the solenoid coil, a magnetic field is generated, lifting the plunger and opening the orifice. This allows the pressurized liquid or gas to flow through the valve and exit the outlet port.
In a normally open solenoid valve, the coil surrounds the armature as in other solenoid designs. However, the spring pushes the plunger upward, keeping the valve open by default. The valve only closes when an electric current passes through the solenoid coil.
When energized, the coil generates an electromagnetic field. In a normally open valve, this field pushes the plunger downward, closing the valve and stopping the flow of liquid or gas. Once the current is turned off, the spring pushes the plunger back up, reopening the valve and allowing fluid or gas to flow continuously through the system.
A normally closed solenoid valve works in the opposite way. Its default resting position is closed, preventing the flow of liquid or gas. In this state, no electric current flows through the coil, and the armature (movable core) rests against the valve seat, blocking the flow.
The solenoid coil surrounds the armature, and a spring holds the plunger in the downward position to keep the valve closed. When electricity is applied, the coil generates a magnetic field, lifting the plunger against the spring. This opens the valve, allowing liquid or gas to pass through.
When the electric current stops, the magnetic field disappears, and the spring pushes the plunger back down, closing the valve again and stopping the flow.
In summary, normally closed valves remain closed until energized, while normally open valves remain open until energized. Both types operate on the same basic solenoid principle, using electromagnetic fields to control the movement of the plunger.
If you have questions about solenoid valves or need help selecting the right type for your system, technical support is available via email, phone, or online chat during regular office hours.
