SMC SQ2431N-5-C6-Q Solenoid Valve – SQ2000 Series

SMC SQ2431N-5-C6-Q: 4/2-Way Single Solenoid Directional Control Valve for Industrial Pneumatic Systems

The SMC SQ2431N-5-C6-Q is a 4/2-way, spring-return, single-solenoid directional control valve from SMC Corporation’s SQ2000 series. Engineered for deterministic pneumatic switching in high-cycle industrial automation environments, this valve delivers a measured response time of ≤15 ms at rated pressure, making it suitable for time-critical actuation sequences in assembly, packaging, and process control applications. Its M5 port configuration and 24 VDC coil voltage align directly with the output specifications of mainstream PLC digital output modules, eliminating the need for intermediate relay stages in most standard control architectures.

The SQ2000 series occupies the compact-body segment of SMC’s directional valve portfolio. The SQ2431N-5-C6-Q body is constructed from die-cast aluminum alloy, providing a favorable strength-to-weight ratio at approximately 100 g per unit. The internal spool is precision-lapped to sub-micron tolerances, ensuring consistent Cv values across the rated pressure band of 0.15–0.7 MPa. The spring-return mechanism guarantees a defined fail-safe position upon de-energization — a mandatory design requirement in safety-instrumented pneumatic circuits where actuator position must be deterministic on power loss.

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Technical Parameters

Hardware Logical Analysis

The SQ2431N-5-C6-Q employs a balanced-spool pilot design in which the solenoid coil generates a magnetic flux path through a laminated iron core, displacing the armature against a calibrated return spring. The 0.5 W energy-saving coil architecture uses a peak-and-hold drive circuit: an initial high-current pulse (typically 3–5× holding current) seats the armature within 8–12 ms, after which the drive circuit reduces current to the holding level, substantially lowering coil temperature rise during continuous energization. This thermal management approach extends coil insulation life in high-duty-cycle applications where the valve may remain energized for extended periods.

The IP65 enclosure rating is achieved through a molded overmold on the coil assembly combined with a face-seal O-ring at the DIN connector interface. This construction prevents ingress of particulate matter ≥1 mm and directed water jets — conditions routinely encountered in wash-down zones and dusty press-shop environments. The LED indicator circuit is wired in parallel with the coil via a built-in rectifier diode, providing visual confirmation of energization state without requiring an external indicator circuit.

EMC performance is addressed through the integrated suppression diode across the coil terminals, which clamps the inductive kick voltage to approximately 1 V above supply rail during de-energization. This eliminates the voltage transient (typically 50–300 V in unsuppressed coils) that would otherwise couple into adjacent signal wiring or damage PLC transistor output stages. Engineers integrating this valve into CE-marked machinery can reference SMC’s Declaration of Conformity, which covers EN 61000-4-2 (ESD), EN 61000-4-4 (EFT/Burst), and EN 61000-4-5 (Surge) immunity levels.

The spool-to-bore clearance is maintained within 3–5 μm across the operating temperature range through matched thermal expansion coefficients between the aluminum body and the hardened steel spool. This dimensional stability preserves internal leakage rates below the rated threshold of 1 cm³/min (at 0.5 MPa) throughout the service life, a parameter critical in multi-valve manifold assemblies where cumulative leakage can degrade system pressure balance.

System Integration Benefits

• Direct PLC Output Compatibility: The 24 VDC / 0.5 W coil load (≈20.8 mA) falls within the rated current of standard transistor output channels on Siemens S7-1200/1500, Mitsubishi FX5U, Omron NX/NJ, and Allen-Bradley CompactLogix, enabling direct connection without interposing relays and reducing panel wiring complexity.
• Deterministic Switching Latency: The ≤15 ms energize response allows motion sequence programmers to assign fixed inter-step delays with confidence, supporting cycle times down to approximately 30 ms per valve actuation in high-speed pick-and-place cells.
• Manifold Scalability: The SQ2431N-5-C6-Q mounts directly onto SMC SS5Q23 and SS5Q24 sub-base manifold blocks, enabling multi-valve islands of up to 16 stations with a single air supply and common electrical bus — reducing pneumatic plumbing labor by eliminating individual body porting.
• Fieldbus Integration: When combined with SMC EX series fieldbus manifold units, the valve island communicates over PROFIBUS-DP, DeviceNet, EtherNet/IP, or EtherCAT, providing per-valve diagnostic data (coil status, cycle count) to the host PLC without additional I/O wiring.
• Fail-Safe Position Assurance: The spring-return mechanism guarantees Port 2 pressurized / Port 4 exhausted upon de-energization, a defined safe state that can be documented in FMEA and HAZOP analyses for machinery safety assessments under ISO 13849.
• Reduced Compressed Air Consumption: The 1.2 mm orifice and optimized spool geometry deliver a Cv of approximately 0.08, sized for actuators in the 10–32 mm bore range. Correct sizing prevents over-specification, which would otherwise increase air consumption and compressor load without performance benefit.
• Diagnostic Transparency via LED: The integral LED provides first-level fault isolation at the valve level — maintenance technicians can confirm coil energization state without a multimeter, reducing mean time to diagnose (MTTD) in multi-valve panels.
• Long Service Interval: The ≥50 million cycle rating at rated conditions translates to approximately 5.8 years of continuous operation at 5 Hz switching frequency, reducing planned maintenance intervals and spare parts inventory requirements in high-throughput production lines.

Quality Assurance & Global Logistics

Every SQ2431N-5-C6-Q unit supplied by siemensplc.com is sourced through verified SMC authorized distribution channels. Each unit is shipped in original SMC factory packaging with intact tamper-evident seals, accompanied by a batch traceability document referencing the SMC production lot number. Prior to dispatch from our Xiamen, China facility, each valve undergoes a three-stage incoming inspection: (1) visual and dimensional check against SMC published drawings, (2) coil resistance measurement (nominal 1,152 Ω ± 10% at 20°C for the 24 VDC / 0.5 W coil), and (3) pneumatic leak test at 0.5 MPa with soapy water immersion to confirm zero external leakage.

Xiamen’s geographic position as a major South China Sea port provides direct access to DHL Express, FedEx International Priority, UPS Worldwide Express, and consolidated sea freight services. Standard air express shipments to Europe and North America transit in 3–5 business days; Southeast Asia destinations typically receive within 2–3 business days. For volume orders, sea freight via Xiamen Port (CNXMN) offers cost-effective delivery to major global ports with full export documentation including commercial invoice, packing list, and certificate of origin. All export shipments comply with applicable export control regulations. A 12-month warranty against manufacturing defects is provided from the date of shipment, with replacement or credit issued upon confirmation of defect.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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