The normally open and normally closed of solenoid valves can be distinguished by the following methods:

The normally open and normally closed of solenoid valves can be distinguished by the following methods:
1、 Working principle
Normally open solenoid valve:
Under normal conditions (when not powered), the valve is in an open state, allowing fluid to pass through.
When the solenoid valve is energized, the valve core is attracted by electromagnetic force, and the valve closes, preventing fluid from passing through.
Normally closed solenoid valve:
Under normal conditions (when not powered), the valve is in a closed state, preventing fluid from passing through.
When the solenoid valve is energized, the valve core overcomes the spring force or other resistance and is opened, allowing fluid to pass through the valve.
2、 Appearance features and identification
Product identification:
Usually, there are clear markings on the valve body of solenoid valves to distinguish between normally open and normally closed types. It may be marked with the words “NO” (Normally Open) or “NC” (Normally Closed).
Electrical parameter identification:
On the technical specifications or nameplate of the solenoid valve, it will also be clearly stated whether it is of the normally open or normally closed type.
3、 Performance in practical applications
Initial state after installation:
Observe the on/off status of the solenoid valve when the system installation is completed and not powered on. If the fluid can pass freely, it is likely to be a normally open solenoid valve; If the fluid is blocked, it may be a normally closed solenoid valve.
Power on test:
Power on the solenoid valve and observe its state changes. A normally open solenoid valve will change from an open state to a closed state, and a normally closed solenoid valve will change from a closed state to an open state.