The HKC APL Series (Covering product lines: APL-2, APL-3, APL-4, APL-5, APL-6, APL-7, APL-8, and APL-9, including models APL-210N, APL-310N, APL-410N, APL-510N, APL-510S, APL-710N, APL-810N, and APL-910N) is manufactured by HKC Co., Ltd., a premier valve automation specialist from South Korea. The APL Series serves as an advanced Valve Position Monitor / Limit Switch Box engineered for direct mounting onto quarter-turn pneumatic actuators or manual valves, providing reliable discrete electrical position feedback to plant-wide DCS/PLC control networks alongside vivid local visual indication.

KEY PRODUCT FEATURES AND OPERATIONAL ADVANTAGES:
1. Complete Portfolio Tailored for Every Operational Environment:
• General Purpose Lines (APL-2, APL-3): Compact die-cast aluminum housing with IP67 weatherproof protection, ideal for commercial water treatment, HVAC, and general manufacturing.
• Explosion-Proof Lines (APL-4, APL-5): Certified Ex db IIB T6 Gb and Ex db IIC T6 Gb (ATEX, IECEx, KCs), engineered specifically for hazardous classified environments in oil refineries and chemical plants.
• Integrated Solenoid Valve Lines (APL-7, APL-8): Features an internal solenoid pilot valve within the switchbox enclosure, minimizing external pneumatic piping and wiring clutter.
• Full Stainless Steel Lines (APL-5S, APL-9): Cast entirely from premium SS304 or SS316L stainless steel for maximum corrosion resistance in offshore marine environments and harsh chemical washes.
2. "Quick-Set" Spring-Loaded Splined Cams:
Equipped with serrated spring-loaded splined cams that allow field technicians to make instant, precise travel limit adjustments by simply pushing and rotating the cam by hand—no screwdrivers or special tools required. The splined teeth lock firmly into place, completely eliminating setting drift under severe plant vibrations.
3. 360° High-Visibility Optical Dome Indicator:
Features a rugged high-visibility visual indicator dome with bright contrasting colors (Yellow/Red or Green/Red for 2-way Open/Close valves, and L/T-port configurations for 3-way valves). The double-sealed construction prevents moisture ingress into the electrical chamber even if the outer indicator dome suffers accidental physical damage.
4. Comprehensive Switch & Sensor Integration:
• Mechanical Microswitches: 2 x SPDT or 4 x SPDT (250V AC 16A/10A) with optional gold-plated contacts for low-current PLC inputs.
• Non-Contact Proximity Sensors: Compatible with world-class inductive sensor brands such as Pepperl+Fuchs (P&F NJ2-V3-N intrinsically safe, NBB3-V3) and Autonics (PS17-5DNU).
• Continuous Position Transmitters (CPT / PIU): Optional 4-20 mA analog output transmitter or 1kΩ/10kΩ potentiometer for continuous 0-90° valve position tracking.
5. Captive Cover Bolts & Spacious Multi-Point Terminal Blocks:
Cover bolts are held captively within the housing to prevent accidental loss during elevated maintenance. The interior contains a spacious angled terminal strip ranging from 8 points (8P) up to 20 points (20P) for clean and effortless wiring.
6. Universal NAMUR VDI/VDE 3845 Mounting Compatibility:
The stainless steel output shaft and mounting brackets conform strictly to international NAMUR standards, ensuring universal bolt-on fitment to any standard pneumatic actuator brand.

TYPICAL INDUSTRIAL APPLICATIONS:
• Oil & Gas and Petrochemical Refineries: Valve position confirmation on crude oil pipelines, gas separator skids, and tank farm manifolds in ATEX/IECEx hazardous areas.
• Water & Wastewater Treatment Plants: Status feedback on intake pump butterfly valves, sedimentation basin isolation valves, and aeration blowdown gates.
• Chemical & Fertilizer Manufacturing: Harsh-environment valve feedback on acid, alkali, and aggressive solvent supply networks.
• Food, Beverage & Pharmaceutical Processing: Sanitary hygienic valve monitoring on automated bottling and cleanroom packaging lines.

• Manufacturer: HKC Co., Ltd.
• Series: APL Series (Valve Position Monitor / Limit Switch Box)
• Brand Origin: South Korea
• Series Lineup & Model Classifications:
  - General Purpose Series: APL-2 (APL-210N, APL-211N, APL-212N, APL-220N), APL-3 (APL-310N, APL-312N, APL-320N)
  - Explosion-Proof Series (Aluminum): APL-4 (APL-410N, APL-420N), APL-5 (APL-510N, APL-520N, APL-510S)
  - Integral Solenoid Valve Series: APL-7 (APL-710N), APL-8 (APL-810N)
  - All-Stainless Steel Heavy Corrosion Series: APL-9 (APL-910N, APL-910S)
• Travel Angle: Standard 0° - 90° (Optional extended range: 0° - 120°, 0° - 135°, 0° - 180°)
• Switch & Sensor Options:
  - Mechanical Microswitches: 2 x SPDT (Standard 250V AC 16A, 125V DC 0.6A) / Optional 4 x SPDT or DPDT
  - 2-Wire Inductive Proximity Sensors (NAMUR): P&F NJ2-V3-N (Ex ia IIC T6)
  - 3-Wire Inductive Proximity Sensors (DC PNP/NPN): P&F NBB3-V3-E2, Autonics PS17-5DNU
  - Continuous Position Transmitters: CPT (4-20 mA DC analog output) or PIU (Potentiometer 1 kΩ / 10 kΩ)
• Cam Adjustment: Quick-Set spring-loaded splined cams (toolless manual adjustment)
• Visual Position Indicator:
  - 2-Way Dome: Open - Yellow / Closed - Red (or Open - Green / Closed - Red)
  - 3-Way Dome: L-port and T-port flow stream configurations
• Housing Materials:
  - Standard & Explosion-Proof Models (APL-2, 3, 4, 5, 7, 8): High-grade die-cast Aluminium alloy with polyester powder coating
  - Stainless Steel Models (APL-5S, APL-9): Cast SS304 or SS316 / SS316L Stainless Steel
• Drive Shaft: Stainless Steel SS304 (Standard) or SS316 (Optional), NAMUR standard
• Cable Conduit Entries: 2 x NPT 1/2" (Standard) or 2 x PF 1/2", 2 x M20 x 1.5, 2 x PG13.5 (Optional APL-4/5: 2 x NPT 3/4", 2 x M25)
• Terminal Block Points: Standard 8 points (8P) / Optional 10P, 12P, 14P, 16P, 20P (wire capacity 0.08 - 2.5 mm²)
• Mounting Brackets: Stainless Steel SS304/SS316 NAMUR VDI/VDE 3845 standard:
  - MBP-100 (30 x 80 mm, H: 20 mm)
  - MBP-200 (30 x 80 mm, H: 30 mm)
  - MBP-300 (30 x 130 mm, H: 30 mm)
  - MBP-400 (30 x 130 mm, H: 50 mm)
• Ingress Protection (Enclosure):
  - Weatherproof Standard: IP67, NEMA Type 4, 4X, 6
  - Submersible Option: Watertight IP68 (10 m depth for 72 hours)
• Explosion-Proof Certifications: Ex db IIB T6 Gb, Ex db IIC T6 Gb, Ex ia IIC T6 Gb, Ex tb IIIC T85°C Db
• International Approvals: ATEX, IECEx, KCs, EAC, CCC, CSA (Class I Div 1 Groups C&D), SIL 2, ABS, RMRS, RINA
• Ambient Operating Temperature:
  - Standard: -20 °C ... +80 °C (Standard models) / -20 °C ... +60 °C (Flameproof models)
  - Low-Temperature Option: -40 °C ... +60 °C (or -50 °C for APL-9 stainless steel)
  - High-Temperature Option: -20 °C ... +120 °C