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Normally open solenoid valve and normally closed solenoid valve difference and selection

In the research and development of solenoid valves, they are usually divided into two types, normally closed and normally open; special solenoid valves are self-retaining.
Normally closed electromagnetic valve means that when the coil is de-energized, the solenoid valve is closed; when the coil is energized, the solenoid valve is opened.
The normally open solenoid valve means that when the coil is de-energized, the solenoid valve opens; when the coil is energized, the solenoid valve closes.
We can choose according to the duration of continuous work: normally closed, normally open, or sustainable power
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 used.
2, when the solenoid valve needs a long time to open, and the opening time is more than the closing time should be selected normally open type.
3, need to open for a long time but also a long time to close, it should be selected from the holding solenoid valve.
4, but some of the conditions for safety protection, such as furnace, kiln flame monitoring, can not be selected normally open, should be selected for long-term power type.
5, for gas alarm system, to use normally open type gas emergency cut off solenoid valve, with manual opening.
Normally-closed solenoid valves are generally used. The structure is simple and the price is low. If the pipe is in circulation for a long time and the pipe closing time is very short, normally open solenoid valves can be used. This is more energy efficient, but the normally open price is slightly higher.
E.g:
The pipeline has been in the water for a long period of time, for a week or even a month. Occasionally, the pipeline is normally closed.
The pipeline circulates the medium for 24 hours. There are several time periods in the middle that need to be closed. The closing time is very short, such as 30 minutes to one hour, which is also more suitable for the normally open type.
The long-term circulation of the pipeline design medium is generally not related, but in the case of emergency, it can also be closed.

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