Selection of normally open and normally closed solenoid valves

Solenoid valve is usually divided into two types: normally closed type and normally open type. Normally closed type is in closed state when power is cut off. When the coil is energized, electromagnetic force is generated to make the moving iron core overcome the spring force and pull in with the static iron core to directly open the valve, and the medium is a channel; When the coil is powered off, the electromagnetic force disappears, the moving iron core is reset under the action of spring force, and the valve port is closed directly, and the medium is not connected. It has the advantages of simple structure, reliable operation and normal operation under zero differential pressure and micro vacuum. The normally open type is just the opposite. Special self retaining solenoid valve, also known as the normally open and normally closed solenoid valve.

We can choose according to the duration of work: normally closed, normally open, or continuously energized.

1. When the solenoid valve needs to be closed for a long time, and the closing time is more than the opening time, the normally closed type should be selected.

2. When the solenoid valve needs to be opened for a long time, and the opening time is more than the closing time, the normally open type should be selected.

3. When it needs to be opened for a long time and closed for a long time, it should be selected from the holding solenoid valve, also known as the normally open and normally closed solenoid valve.

4. However, for some working conditions used for safety protection, such as furnace and kiln flame monitoring, the normally open type cannot be selected, and the long-term electrified type should be selected.

5. For gas alarm system, normally open gas emergency shut-off solenoid valve with manual opening shall be selected.