Airtac Solenoid Valve Selection Golden Rules: Four Principles and Six-Step Process

While solenoid valve selection may seem straightforward, choosing the correct model can boost system efficiency by 30% and cut failure rates by 80%. Conversely, an incorrect choice can lead to leaks, sticking actions, shortened lifespan, or even the shutdown of an entire production line. Airtac, a global leader in pneumatic components, offers a full range of solenoid valve products (3V, 4V, 6V, 4M, etc.). But how do you accurately match a model to your application? This article will share the "Four Golden Rules" and the "Six Practical Steps" for solenoid valve selection, helping you avoid common pitfalls and choose the Airtac valve that offers the "best value for money and strongest compatibility."

I. Four Golden Selection Principles: Define Core Needs First

1. Safety Principle: Prioritize Personal and System Safety

Key safety indicators must be closely monitored during selection:

  • Voltage Matching: Strictly verify that the coil's rated voltage (e.g., $\text{AC}220\text{V}$, $\text{DC}24\text{V}$) matches the power supply, with a voltage tolerance $\le \pm 10\%$, to prevent coil burnout or electrical short circuits.

  • Pressure Rating: The actual operating pressure must be $\le$ the valve's rated working pressure (e.g., $0.15 \sim 0.8 \text{MPa}$ for the 4V series), and the maximum withstand pressure should be $\ge 1.2$ times the working pressure to prevent valve body rupture due to overpressure.

  • Explosion/Protection Needs: Select $E_x$ explosion-proof certified models for hazardous environments, and choose IP65 or higher ingress protection for outdoor or damp conditions.

2. Reliability Principle: Long-Term Stability Matching Operating Conditions

  • Media Compatibility: Select standard models for gaseous media (air, nitrogen), waterproof/sealed models for liquid media (water, oil), and stainless steel valve bodies + Fluororubber (FKM) seals for corrosive media.

  • Temperature Adaptability: Choose FKM seals for high-temperature environments ($>60^\circ\text{C}$), and Silicone rubber (VMQ) seals for low-temperature environments ($<-20^\circ\text{C}$), to prevent seal aging and failure.

  • Lifespan Matching: For high-frequency applications ($>1$ cycle/second), select models with a mechanical life $\ge 10$ million cycles (e.g., 4V400 series) to avoid frequent replacement.

3. Applicability Principle: Align Installation and Control Requirements

  • Installation Space: Select miniature 3V series models (volume $\le 45\text{mm} \times 25\text{mm}$) for small equipment, or 6V/HV manifold valves (modular integration) for large systems.

  • Control Method: Choose single-solenoid models for single-direction movement, double-solenoid models for bi-directional holding actions, and direct-acting models (3V series) for vacuum applications.

  • Port Matching: Ensure the air tubing/piping specifications match the solenoid valve port size (e.g., $G1/4"$, $G1/2"$) to avoid unnecessary adapters.

4. Economic Principle: Optimize Total Cost, Not Just Unit Price

  • Avoid Oversizing: Select the effective flow area ($C_v$ value) based on the flow demand. For small cylinders (bore $\le 32\text{mm}$), choose $C_v = 0.5 \sim 1.0$ (3V/4V100 series). Avoid large-flow models (like 4V400 series $C_v=3.0$) to save procurement costs.

  • Consider Operating Costs: Prioritize lubrication-free, long-life models (e.g., 4V series with $7.5$ million cycle mechanical life) to reduce long-term maintenance and replacement expenses.

II. Six-Step Practical Process: Step-by-Step Precise Selection

Step 1: Define Control Object and Action Requirements

First, determine the solenoid valve's control objective: driving a cylinder (single-acting/double-acting), controlling a process valve (on/off, proportional), vacuum adsorption, etc. Clarify the action logic: Normally Closed (power off = closed), Normally Open (power off = open), shifting frequency (cycles/second), and response time requirement ($\le 0.05$ seconds).

Example: Control a double-acting cylinder (bore $63\text{mm}$), high-frequency shifting (2 cycles/second), requires holding the current position upon power loss $\rightarrow$ Select a double-solenoid, large-flow model.

Step 2: Confirm Working Medium and Environmental Parameters

  • Medium Type: Air, nitrogen, water, hydraulic oil, corrosive gas, etc.

  • Medium Temperature: Operating environment temperature (e.g., workshop ambient $25^\circ\text{C}$, outdoor $-30^\circ\text{C}$, equipment vicinity $80^\circ\text{C}$).

  • Environmental Conditions: Is it damp, dusty, vibrating, corrosive? Is explosion proofing needed?

Example: Medium is dry air, ambient temperature $-10^\circ\text{C} \sim 50^\circ\text{C}$, dusty workshop $\rightarrow$ Select a standard aluminum alloy valve body, FKM seals, IP65 protection model.

Step 3: Determine Working Pressure and Flow Requirements

  • Working Pressure: The system's normal operating pressure (e.g., $0.4 \text{MPa}$), which must be within the valve's rated pressure range (e.g., 4V series $0.15 \sim 0.8 \text{MPa}$).

  • Flow Demand: Calculate the required effective flow area ($C_v$ value) based on the actuator (e.g., cylinder) bore, stroke, and operating frequency. The formula reference is: $C_v = Q \times \sqrt{P_1/P_2}$ (where $Q$ is flow, $P_1$ is inlet pressure, $P_2$ is outlet pressure).

Example: Cylinder bore $63\text{mm}$, stroke $100\text{mm}$, operating frequency 2 cycles/second, calculation yields $C_v \ge 2.0 \rightarrow$ Select a model with effective flow area $\ge 35\text{mm}^2$ (e.g., 4V310-10, $C_v = 2.1$).

Step 4: Choose Valve Type and Control Method

  • Valve Type:

    • Direct-Acting (3V series): Zero-pressure start-up, suitable for vacuum and low-pressure applications.

    • Internal Pilot (4V series): Low-pressure start-up + high flow, suitable for general industrial applications.

    • Manifold (6V/HV series): Multi-valve integration, suitable for large systems.

    • NAMUR Interface (4M series): Suitable for process industry valve actuators.

  • Control Method:

    • Single Solenoid: Energized to shift, de-energized to reset (by spring), suitable for single-direction movement.

    • Double Solenoid: Energized to shift, de-energized to hold the current state, suitable for bi-directional movement.

Step 5: Match Voltage and Port Specifications

  • Voltage Selection:

    • $\text{AC}220\text{V}/\text{AC}110\text{V}$ for centralized industrial power (non-polarity sensitive, simple wiring).

    • $\text{DC}24\text{V}/\text{DC}12\text{V}$ for small control units (PLC, sensors) (low power consumption, suitable for battery power).

  • Port Specifications: Select based on tubing/piping size. Common specifications:

    • $G1/8"$ (3V100 series): Suitable for $\phi 4/\phi 6$ tubing.

    • $G1/4"$ (4V200 series): Suitable for $\phi 6/\phi 8$ tubing.

    • $G1/2"$ (4V400 series): Suitable for $\phi 12/\phi 16$ tubing.

Step 6: Verify Model Code and Final Selection

Airtac solenoid valve model codes follow a fixed structure. Taking 4V410-15 DC24V as an example:

  • 4V: Series (Internal Pilot 5-port 2-position).

  • 410: Specification ($410 = 50\text{mm}^2$ effective flow area).

  • 15: Port Size ($15 = G1/2"$).

  • DC24V: Voltage Specification.

Cross-check each part of the model code against the requirements defined in the first five steps to ensure consistency with the actual need. For special requirements (e.g., explosion-proof, low-temperature), contact the supplier for custom models.

III. Common Selection Pitfalls: Avoid These Traps

  1. Only Looking at Port Size, Ignoring Effective Flow Area: For example, both $G1/4"$ ports are used on the 4V210-08 ($C_v=1.0$) and 4V310-10 ($C_v=2.1$), but the flow difference is significant. Selection must be based on the actuator's flow demand.

  2. Confusing AC and DC Voltage: $\text{AC}24\text{V}$ and $\text{DC}24\text{V}$ models look similar, but incorrect connection will burn the coil. The voltage type must be clearly specified during selection.

  3. Ignoring Medium Temperature: Using standard Nitrile rubber (NBR) seals in high-temperature environments will lead to seal softening and leakage. FKM material must be selected.

  4. Selecting Pilot-Operated Valves for Vacuum Applications: Pilot-operated valves require a minimum pilot pressure $\ge 0.15 \text{MPa}$ to actuate. For vacuum applications (pressure $< 0.1 \text{MPa}$), a direct-acting valve (3V series) must be chosen.

Summary

The core of Airtac solenoid valve selection is to "define needs first, then match parameters"—by adhering to the four principles of safety, reliability, applicability, and economy, and following the six-step process of "Define Control Object $\rightarrow$ Confirm Environment Parameters $\rightarrow$ Determine Pressure & Flow $\rightarrow$ Choose Valve Type $\rightarrow$ Match Voltage & Port $\rightarrow$ Verify Model Code," you can precisely select the right model. If you still have selection doubts, you can contact the Airtac technical team, provide your operating parameters, and receive one-on-one selection advice.

Call to Action (CTA)

  • Selection Consultation: Submit your operating parameters (medium, pressure, temperature, actuator) to receive customized model recommendations.

  • Download Selection Manual: https://www.airtac-shop.com (Technical Support - Selection Tools)

  • Model Inquiry: Use the "Model Code Inquiry" function on the Airtac official website to quickly match parameters.

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