Electromagnetic valves are usually divided into two types: normally open and normally closed. Normally open solenoid valve refers to the opening of the solenoid valve when the coil is powered off; When the coil is energized, the solenoid valve closes. A normally closed solenoid valve refers to a solenoid valve that closes when the coil is powered off; When the coil is energized, the solenoid valve opens.

We can choose between normally closed or normally open based on the duration of continuous work.

1、 When the solenoid valve needs to be closed for a long time, and the closing time is longer than the opening time, and the continuous opening time is not very long, the normally closed type can be selected

2、 When it is necessary to open and close for a long time, a holding solenoid valve, which is a normally open and normally closed solenoid valve, should be selected

3、 When the solenoid valve needs to be opened for a long time, and the opening time is longer than the closing time, and the continuous opening time is not very long, the normally open type can be selected

4、 Or for gas alarm systems, a normally open gas emergency shut-off solenoid valve with manual opening should be selected

5、 However, some working conditions that require safety protection, such as furnace and kiln fire monitoring, cannot be selected as normally open, and should be selected as those that can be powered on for a long time