The working principle of the gas solenoid valve is to use the direct control of the spool closing valve (or opening valve). When the coil is energized, electromagnetic force will be generated, so that the internal iron core will drive the spool closing valve, thus cutting off the gas transmission.Solenoid valve is usually divided into normally open type and normally closed type.
Normally open solenoid valve refers to when the coil is out of power, the solenoid valve open;When the coil is energized, the solenoid valve closes.
Normally closed solenoid valve refers to when the coil is out of power, the solenoid valve closed;When the coil is energized, the solenoid valve opens.
Household solenoid valves and common gas solenoid valves are normally open solenoid valves.The normally open solenoid valve, as a controlled device, should be connected to the pulse signal output end when connected with the control end (such as household alarm, controller).Normally closed solenoid valve is often used in the electric on and off occasions.The solenoid valve, as a controlled device, shall be connected to the holding signal output end when connected to the control end (such as the controller).
The normally closed or normally open type is selected according to the duration of the work:
1. When the solenoid valve needs to be closed for a long time, and the closing time is more than the opening time.And if you don't keep it on for very long, you can choose the normally closed type.
2. When opening for a long time and closing for a long time, choose self-retaining solenoid valve, that is, normally open and normally closed solenoid valve.
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, you can choose the normally open type.
4. or used for gas alarm system, to choose the normally open gas emergency cut-off solenoid valve, with manual opening.
However, for some working conditions that need to be applied to safety protection, such as furnace and kiln fire monitoring, those that are normally on should be selected instead of those that can be powered on for a long time.
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