Normally Open: When the coil is energized, the pilot hole closed, the valve chamber and pressurized by the piston return spring throttle thrust, the electromagnetic valve is closed.

常开：当线圈通电时，先导孔关闭，阀上腔由活塞节流孔增压和复位弹簧的推力，电磁阀关闭。

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When the coil power, the pilot valve by the spring return, pilot hole open, pressure relief valve on the chamber, the piston on the lower chamber medium pressure to promote the solenoid valve open.

当线圈断电时，先导阀芯靠弹簧复位，先导孔打开，阀上腔卸压，活塞靠下腔介质压力推动，电磁阀打开。

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When the coil power, the pilot valve by the spring return, pilot hole closed throttle valve chamber pressurized by the piston return spring and thrust, the electromagnetic valve is closed.

当线圈断电时，先导阀芯靠弹簧复位，先导孔关闭，阀腔由活塞节流孔增压和复位弹簧的推力，电磁阀关闭。

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