Classification of explosion-proof solenoid valves

Jan 17, 2020

1. Solenoid valves are divided into three categories in principle:

1) Direct acting solenoid valve:

Principle: when energized, the electromagnetic force generated by the electromagnetic coil lifts the closing part from the valve seat and opens the valve; when the power is cut off, the electromagnetic force disappears, and the spring presses the closing part on the valve seat and closes the valve.

Features: it can work normally in vacuum, negative pressure and zero pressure, but the diameter is generally not more than 25 mm.

2) Direct acting solenoid valve:

Principle: it is a combination of direct acting and pilot type. When there is no pressure difference between the inlet and the outlet, the electromagnetic force will directly lift the small pilot valve and the main valve closure piece upward one by one, and the valve will open. When the pressure difference between the inlet and the outlet reaches the starting pressure, the small solenoid pilot valve will increase the pressure in the lower chamber of the main valve and decrease the pressure in the upper chamber after being powered on, so as to push the main valve upward by using the pressure difference; when the power is off, the pilot valve will use the spring force or the medium pressure to push the closure piece and move downward to close the valve.

Features: it can also act under zero pressure difference, vacuum or high pressure, but it has high power, so it must be installed horizontally.

3) Pilot operated solenoid valve:

Principle: when the power is on, the electromagnetic force opens the pilot hole, the pressure of the upper chamber drops rapidly, forming a high and low pressure difference around the closing piece, the fluid pressure pushes the closing piece to move upward, and the valve opens; when the power is off, the spring force closes the pilot hole, and the inlet pressure quickly forms a low and high pressure difference around the closing piece through the bypass hole, and the fluid pressure pushes the closing piece downward Move and close the valve.

Features: the upper limit of fluid pressure range is high, which can be installed arbitrarily (customized) but must meet the condition of fluid pressure difference.

2. The solenoid valve is divided into six sub categories according to the difference in valve structure and material and the difference in principle:

Direct acting diaphragm structure, step-by-step heavy plate structure, pilot membrane structure, direct acting piston structure, step-by-step direct acting piston structure and pilot piston structure.