The explosion-proof solenoid valve is divided into 3 main categories in principle.
1. Direct acting solenoid valve:
Its main principle is that when electrified, the electromagnetic coil will produce electromagnetic force to lift the closure from the seat, and then the valve will open; when the power is cut off, the electromagnetic force disappears, the spring will press the closure on the seat, and the valve will close.
This kind of characteristic can work normally in vacuum, negative pressure and zero pressure, but the diameter is generally not more than 25MM.
2. Pilot type solenoid valve:
Its principle is that when electrified, the electromagnetic force opens the pilot hole, the pressure of the upper chamber drops rapidly, and a high pressure difference is formed around the closing part. The fluid pressure pushes the closing part upward and the valve opens. When the power is cut off, the spring force closes the pilot hole, and the inlet pressure forms rapidly around the closing part through the bypass hole. The lower pressure is higher and higher, and the fluid pressure pushes the shut-off parts to move downwards, closing the valve.
The characteristic of this kind of solenoid valve is that the upper limit of fluid pressure range is high, and it can be installed arbitrarily (customized), but it must satisfy the condition of fluid pressure difference.
3. Distributing direct acting solenoid valve:
This kind of electromagnetism is the combination of the first two kinds. When it is electrified, the electromagnetic force directly lifts the pilot valve and the main valve closing parts up in turn, and the valve opens. When the inlet and outlet reach the start-up pressure difference, after electrification, the electromagnetic force leads the small valve, the lower chamber pressure of the main valve rises and the upper chamber pressure decreases, so that the main valve is pushed upward by the pressure difference; when the power is cut off, the pilot valve uses spring force or medium pressure to push the closing parts downward, so that the valve closes.
It is characterized by zero differential pressure or vacuum, high voltage can also * action, but the power is large, requires horizontal installation.
