Dec 03, 2025
A double-acting solenoid valve is a type of pneumatic solenoid valve used to control double-acting cylinders. In a double-acting cylinder, air pressure is used to drive the cylinder in both directions—extension and retraction. Unlike single-acting cylinders, which rely on a spring for return, the movement of a double-acting cylinder in both directions requires control by an air supply.
A double-acting solenoid valve is a type of solenoid valve specifically designed for complex system structures.The key components of a double acting solenoid valve are different from those of a single acting valve,the following are its main structural components:
Two coils: two independent electromagnetic coils located at both ends of the valve.
Valve core: a component that slides in a precision inner hole and connects or blocks the flow path through its shoulder and groove.
Valve body: includes an inner hole for the valve core and an external interface.
Sealing element: prevents leakage between the valve core and valve body.
The most crucial thing is that it does not have a spring like the single solenoid valve. The switching and maintenance of the valve core rely entirely on electromagnetic force and fluid pressure.
A typical five port two position (5/2) double acting solenoid valve is commonly used to control double acting cylinders. It has five interfaces: an intake port (P), two exhaust ports (R, S), and two working ports (A, B).
Action: Send a brief electrical pulse to coil A.
Valve core movement: The magnetic force generated by coil A pushes the valve core to move to the right.
Flow path:
The gas source flows from port P to port A.
Connect port B to exhaust port S.
This usually drives the cylinder to extend.
Maintain position: After the valve core moves to the right position, the fluid pressure acting on both ends will firmly hold it in this position, even if the pulse signal of coil A has disappeared. The valve "remembers" this state.
Action: Send a brief electrical pulse to coil B.
Valve core movement: The magnetic force generated by coil B pulls the valve core to move to the left.
Flow path:
The gas source flows from port P to port B.
Connect port A to exhaust port R.
This usually drives the cylinder to retract.
Maintain position: Similarly, fluid pressure will firmly hold the spool in this new left position. The valve "remembers" this new state.
When there is a power outage, this is the most important difference between double acting valves and single acting valves:
When both coils are powered off, the valve will not operate. It will remain in its last triggered position.
This is a 'hold' or 'memory' function. If the power supply is interrupted, the cylinder controlled by this valve will remain extended or retracted.
| Feature | Single-Acting Solenoid Valve | Double-Acting Solenoid Valve |
|---|---|---|
| Number of Coils | One | Two |
| Return Mechanism | Spring | Fluid Pressure |
| Default State | Yes (Normally Open or Normally Closed) | No. It has two stable working positions. |
| State after Power Loss | Returns to the spring-default position. | Remains in the last active position. |
| Power Consumption | Power required only to actuate against the spring (in one direction). | Requires only a brief pulse signal to change state; does not need continuous power. |
| Common Symbol | 3/2 (3-port, 2-position) | 5/2 (5-port, 2-position) or 4/2 (4-port, 2-position) |
| Controlled Actuator Type | Single-Acting Cylinder (with a spring) | Double-Acting Cylinder (without a spring) |
Double acting solenoid valves are crucial for controlling double acting cylinders, as both the extension and retraction of the cylinder require power.
Industrial automation: robot arms, fixtures, stamping machines.
Material handling: conveyor belt baffle, pusher, elevator.
Automotive manufacturing: used for welding and assembly lines.
Packaging machinery: used for complex power driven actions.
Controlling a double-acting cylinder to extend and retract a robotic arm.
the upward and downward movement of the hydraulic press slide.
| Item | Double-Acting Pneumatic Solenoid Valve | Double-Acting Hydraulic Solenoid Valve |
|---|---|---|
| Working Medium | Compressed air | Hydraulic oil |
| Typical Working Pressure | 0.3–0.8 MPa (low pressure) | 10–35 MPa (high pressure), or higher |
| Actuator Driven | Double-acting pneumatic cylinder | Double-acting hydraulic cylinder |
| Main Applications | Light-load, high-speed motion | Heavy-load, high-force, precise control |
| Valve Body Materials | Aluminum alloy, plastics, lightweight materials | Steel, cast iron, reinforced metal structures |
| Response Speed | Fast, suitable for high-frequency actuation | Slower, but more stable and powerful |
| Control Precision | Medium (air is compressible) | High (liquids are essentially incompressible) |
| Common Valve Types | 5/2, 4/2 double-solenoid valves | 4/3, 4/2 double-solenoid directional control valves |
| Load Level | Light to medium loads | Medium to heavy loads |
| Leakage Impact | Air leakage acceptable | Oil leakage serious (contamination + efficiency loss) |
| Maintenance Difficulty | Low, clean system | Higher, requires fluid cleanliness and sealing maintenance |
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Answer: Leaks are usually caused by damaged or worn seals, dirt or debris inside the valve, improper installation, or excessive pressure. Regular maintenance and proper installation can prevent leaks.
Answer: A normally open 2-way solenoid valve stays open when unpowered and closes when powered. It is suitable for controlling water, oil, or air flow in simple on/off applications.
Answer: Material choice depends on the fluid type, pressure, temperature, and corrosion resistance requirements:
Plastic: lightweight, chemical resistance, low pressure
Brass: durable, moderate pressure, common in water/oil/air
Stainless steel: high corrosion resistance, suitable for harsh or high-temperature conditions
Answer: Reversing inlet and outlet may cause the valve to malfunction, reduce flow efficiency, or damage seals. Always follow the manufacturer’s flow direction markings.
Answer: You can test by applying the correct voltage and observing the valve action (opening/closing). Additionally, measure coil resistance with a multimeter to check for continuity or shorts.
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