1. Normally Closed Solenoid Valve
This is the most commonly used type.
Operating State: When de-energized, the valve port is closed due to spring force or fluid pressure, blocking the fluid flow. When the coil is energized, electromagnetic force is generated, which pulls the valve core up, overcoming the spring force and opening the valve port, allowing fluid to flow. When de-energized, the electromagnetic force disappears, and the valve core returns to its original position under the action of the spring, closing the valve port again.
Features: Simple structure, reliability, and low leakage.
Applications: Suitable for most applications where a pipeline must remain normally closed, allowing fluid to flow only temporarily when needed.
For example: filling a coffee machine, cleaning printer nozzles, automatic sprinkler systems, start-stop control of pneumatic equipment, and metered drug delivery in medical devices.
2. Normally Open Solenoid Valve: The opposite of the normally closed type.
Operating State: When de-energized, the valve port is open due to spring force, allowing fluid to flow freely. When the coil is energized, electromagnetic force pulls the valve core in, closing the valve port and blocking the fluid flow. After power is removed, the valve reopens.
Features: Suitable for applications where the pipeline must remain open and flow must be shut off only in exceptional circumstances.
Applications: Relatively rare, primarily used for safety protection and cooling system circulation.
For example: Equipment safety vents (powered on and closed in an emergency) and cooling circuits requiring long-term circulation (powered on and closed only for maintenance).
