Duplomatic DS3 & DS5 Series Proportional Directional Valve

The DS3, DS5, and DL3 series (encompassing specific industrial engineering codes such as DS3-RK/11N-D220K1 and DS3-S3/11N-D24K1) manufactured by LIC Hydraulic are heavy-duty, high-performance directional fluid control solenoid and proportional valves. They are engineered as core fluid components for high-frequency, precision-cycling applications in industrial automation, hydraulic power units (HPUs), and automated manufacturing processing lines. Designed to strict international standards including CETOP 03 (ISO 4401-03) and CETOP 05 (ISO 4401-05) mounting interfaces, unified subplate bolt patterns, industry-standard electrical junction profiles, and optimized centring spring dynamics, this complete product line offers 100% drop-in interchangeability with the classic DS3, DS5, and DL3 series directional valves from Duplomatic.

In demanding automation loops, directional solenoid valves operate under strenuous conditions defined by high-frequency cyclic shifting, sustained peak pressure spikes, and fluid-shear erosion. Standard commercial grade valves frequently succumb to hydraulic lock, coil burnout caused by excessive thermal buildup, or massive system energy degradation stemming from poorly cast internal passages. LIC addresses these vulnerabilities via advanced hydro-machined internal coring and using high-strength ductile iron castings paired with hardened steel spools with dynamic pressure-equalizing grooves. Every valve module undergoes 100% factory verification testing under realistic system high-pressures, including internal leakage auditing and electrical insulation overload inspection prior to boxing. This ensures swift switching response and consistent volumetric tracking up to 350 bar, rendering LIC the preferred choice for global B2B machine tool OEMs and hydraulic block aggregators.

Technical Specifications

Engineering parameters verified against official Duplomatic technical catalogs for the DS3-RK/11N-D220K1 setup and overlapping matrices:

• Product Series: DS3 / DS5 / DL3 High-Pressure Direct-Acting Directional Solenoid Valve Platform

• Model Number Specification Code Breakdown (DS3-RK/11N-D220K1):

  • DS3: CETOP 03 / ISO 4401-03 / Nominal Size DN 6 standard mounting interface configuration.

  • RK: Spool type and mechanism modifier, defining a 2-position single-solenoid configuration equipped with a mechanical detent positioning device.

  • 11: Design series classification index (Dimensionally identical and completely backward compatible across 10-19 configuration brackets).

  • N: Elastomer sealing material specification, utilizing Nitrile (NBR) compound standard for standard petroleum-base fluids.

  • D220: Solenoid excitation coil rating, 220V DC rectified voltage system (complete with internal rectifier bridge integrated within the junction box).

  • K1: Electrical connector configuration interface, conforming to standard EN 175301-803 (formerly DIN 43650) Form A three-terminal plug setup.

• Nominal Interface Classification Norms:

  • DS3 / DL3 Series: CETOP 03 / ISO 4401-03-02-0-05 (DN6)

  • DS5 Series: CETOP 05 / ISO 4401-05-04-0-05 (DN10)

• Maximum Permissible Operational Pressure Ratings:

  • P, A, B Ports: Up to 350 bar (35 MPa / 5076 psi)

  • T (Return) Port Backpressure Boundary: Up to 210 bar for DC solenoids; Up to 160 bar for AC coils.

• Maximum Volumetric Flow Capability Limit:

  • DS3 / DL3 Series: Up to 100 L/min (26.4 GPM)

  • DS5 Series: Up to 150 L/min (39.6 GPM)

• Actuation Mechanism: Wet-pin, oil-immersed direct-acting solenoid thrust configuration.

• Net Unit Weight Benchmark: Single-solenoid variants (DS3) approx. 1.5 kg; Double-solenoid configurations (DS3) approx. 2.0 kg.

Key Technical Advantages

• Investment-Cast High-Tensile Iron Body with Streamlined Flow Cavities: The valve body is investment cast using high-strength ductile iron. This smooth cored internal design eliminates sharp flow angles and vortex zones, reducing pressure drop ($\Delta P$) by over 30% compared to standard sand-cast bodies to help improve overall system efficiency.

• Hydrodynamically Balanced Micron-Tolerance Spool Geometry: The alloy steel spools undergo precision heat treatment and centerless grinding to hold a tight 3-5 $\mu m$ radial clearance fit inside the valve bore. Multiple circumferential fluid-balance rings machined into the spool land create a consistent oil film that counters lateral hydraulic locking forces, ensuring reliable shifting even at a sustained 350 bar load.

• Wet-Pin Oil-Immersed Armature Structure: The solenoid armature tube is open to the valve tank return path, keeping all moving parts completely submersed in hydraulic fluid. This fluid cushion dampens mechanical impacts and vibration during shifting, while continuous oil flow draws thermal energy away from the coil to help prevent heat-induced insulation breakdown under high cyclic duty.

• Fatigue-Resistant High-Cycled Centring Springs: Precision wound from imported premium music wire, the internal spring components undergo an intensive 10-million-cycle full-stroke fatigue qualification program. This high-tensile spring resilience ensures reliable, repeatable spool return to the neutral position within 30 milliseconds after coil de-energization, eliminating shifting lag.

Application Areas

The DS3-RK/11N-D220K1 and DS5 series valves offer rapid response times and dependable shifting performance, making them standard control components in various manufacturing environments:

• High-Speed CNC Metal Cutting Machine Tools: Power control for automated workpiece clamping actuators, turret indexing rings, and high-velocity tool changer arm circuits.

• Industrial Plastics Processing & Injection Molding Machinery: Core spool control for proportional pre-plasticizing blocks, hydraulic safety gate interlocks, and ejector ram positioning manifolds.

• Heavy Hydraulic Presses, Punching Equipment, & Ironworks Machinery: Serving as the pilot stage driver mounted atop large high-flow proportional logic cartridge arrays.

• Automated Logistics lines & Scissor Lift Platform Assemblies: Providing precise control for lift cylinders and main drive motor manifolds requiring frequent stop-start cycling.

Expert Maintenance Tips

• Avoid Aggressive Manual Override Impacts Under High System Static Pressure: When debugging electrical logic or verifying movement manually during power interruptions, technicians often actuate the spool using a screwdriver against the manual override pin. Never strike or apply excessive force to this pin when the valve core is completely dry or under high internal static pressure. Doing so can deform the internal guide sleeve and tear the surrounding elastomeric seal, leading to persistent fluid weeping.

• Maintain Rigid System Fluid Filtration Levels (Target NAS 8 / ISO 4406 19/16/13): Direct-acting spool valves use precise micro-clearances between moving parts. If a system’s oil ages or filtration fails, microscopic hard particulate can settle in the clearance zones, acting like fine sandpaper and scoring the precision spool lands. To prevent premature wear, install a high-pressure line filter with a rating of 10 $\mu m$ or finer directly upstream of the valve’s pressure port.

• Verify Solenoid Thrust Force Profiles Prior to Swapping AC and DC Coils: If an electrical controls modification requires substituting a standard DC coil (such as D24) with an AC variant (such as A230), verify that the centring spring rate matches the distinct magnetic force profiles of the new armature setup. For specialized detent models like the RK series, avoid loosening the armature tube locking collar to prevent the internal spring-loaded positioning bearings from displacing.