How to Select a Solenoid Valve for Single-Acting and Double-Acting Cylinders

In pneumatic and automation systems, choosing the appropriate solenoid valve for single-acting and double-acting cylinders is a critical step to ensure stable system operation, achieve desired speed, and extend the equipment's service life. Selecting the right valve depends not only on port size and Cv flow rate, but also on the series and AirTAC model that matches the cylinder's pressure and size.

This article will guide you on how to distinguish between single- and double-acting cylinders, the valve connection principles, technical factors for valve selection, and how to refer to the AirTAC solenoid valve catalog to choose the appropriate model.

1. Concept of Single-Acting and Double-Acting Cylinders

Single-Acting Cylinder

1. Uses air pressure to move in one direction; the return motion is assisted by a spring or gravity.
2. Typically used in applications requiring simple strokes and lower cost.

Double-Acting Cylinder

1. Air pressure provides force in both directions (push and pull), allowing precise position and speed control.
2. Commonly used in systems requiring cyclical movement or heavy loads.

To better understand the internal structure, you can refer to the article “Construction of AirTAC Solenoid Valves (Aluminum Body, Solenoid Coil)”.

2. Solenoid Valve Connection Principles

1. Single-Acting Cylinder: Uses a 3/2-way valve; air enters one port, and the other port vents to the atmosphere.
2. Double-Acting Cylinder: Uses a 5/2-way valve; air alternates to both cylinder ports, causing the piston to extend and retract.

Note: Selecting the correct valve type ensures rapid cylinder response and prevents vibration or failure to actuate.

3. Technical Factors When Choosing a Valve

3.1 Port Size & Flow Rate (Cv)

1. Determine the required airflow according to cylinder size.
2. Larger port size → higher Cv → can deliver greater airflow.
3. Matching port size and Cv ensures the valve and cylinder operate smoothly.

3.2 Coil Voltage

1. Choose AC or DC according to system supply to prevent coil burnout or valve malfunction.

3.3 System Pressure

1. The valve must withstand the cylinder's maximum operating pressure.
2. Cv and port size should be compatible with the operating pressure to prevent excessive pressure drop.

3.4 Valve Model and Series

1. AirTAC 4SV Series: 4V100 → 4V400, port size 1/8 – 1/2 inch, Cv varies per model.
2. AirTAC 7SV Series: 7SV050 → 7SV330, higher flow and pressure, suitable for heavy-duty industrial systems.

4. Selecting a Valve Using the AirTAC Catalog

4SV Series

1. Choose the model based on required airflow, system pressure, and number of valve positions.
2. Example: Small cylinder → 4SV110 or 4SV120, medium cylinder → 4SV210 or 4SV220.

7SV Series

1. Choose models for high airflow or high-pressure systems.
2. Example: 7SV100, 7SV220, 7SV310.

5. Installation and Connection Guidelines

1. Check port size and Cv before installation to ensure the valve matches the cylinder.
2. Connect the coil properly: vertical plug wire or parallel plug wire.
3. When using a manifold, Cv values of all connected valves must be consistent.
4. Tighten screws appropriately to prevent air leakage and valve damage.

A correctly selected valve ensures that single- or double-acting cylinders operate accurately, prevents valve vibration, and maintains efficient pneumatic system performance.