According to the principle of the classification of solenoid valves

Direct-acting solenoid valve:

Principle: When energized, the solenoid generates electromagnetic force to lift the closing member from the valve seat, and the steam solenoid valve opens; when the power is off, the electromagnetic force disappears, and the spring presses the closing member on the valve seat to close the valve.

Features: It can work normally under vacuum, negative pressure and zero pressure, but the diameter generally does not exceed 25mm.

Distributed direct-acting solenoid valve:

Principle: It is a combination of direct-acting and pilot-operated principle. When there is no pressure difference between the inlet and the outlet, the electromagnetic force directly lifts the pilot small valve and the main valve closing member in turn, and the valve opens. When the inlet and outlet reach the starting pressure difference, after power on, the electromagnetic force pilots the small valve, the pressure in the lower chamber of the main valve rises, and the pressure in the upper chamber drops, so that the pressure difference pushes the valve actuator main valve upward; when the power is off, the pilot The valve uses spring force or medium pressure to push the closing piece and move downward to close the valve.

Features: It can also be operated under zero pressure difference or vacuum and high pressure, but the power is large, and it must be installed horizontally.

Pilot solenoid valve:

Principle: When energized, the electromagnetic force opens the pilot hole, the pressure in the upper chamber drops rapidly, and a high pressure difference is formed around the closing part. The fluid pressure pushes the closing part to move upward and the valve opens; when the power is off, the spring force controls the pilot The hole is closed, and the inlet pressure quickly passes through the bypass hole to form a low and high pressure difference around the valve closing member. The fluid pressure pushes the closing member to move downward to close the valve.

Features: The upper limit of the fluid pressure range is relatively high. The high temperature solenoid valve can be installed arbitrarily (customization is required) but must meet the fluid pressure difference condition.

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