Sankyo Seisakusho S-K16-AH Float Level Switch

SANKYO SEISAKUSHO S-K16-AH TOP-MOUNT MAGNETIC FLOAT LEVEL SWITCH

The Sankyo Seisakusho S-K16-AH is a top-mounted magnetic float level switch engineered for high-reliability high-level (alarm/trip) and low-level control across shipboard and industrial process tanks. Built in Japan by Sankyo Seisakusho Co., Ltd., the S-K16 series employs a mechanically decoupled magnetic actuation mechanism that ensures a complete hermetic barrier between the process medium and the electrical switching compartment.

Comes with continuous structural vibration, sloshing, mechanical shock, and aggressive environments (HFO, MDO, lube oil, bilges, cooling water, chemical sumps), the S-K16-AH eliminates fluid bypass risks common to packings and dynamic shaft seals. Its microswitch contact assembly is rated up to 15A at 125/250/480V AC and 0.5A at 30V DC, allowing direct control of pilot circuits, intermediate relays, solenoid valves, or direct integration into distributed alarm monitoring systems (AMS) and PLC-based engine room automation architectures.

Model Details

• Manufacturer: Sankyo Seisakusho Co., Ltd. (Tokyo, Japan)
• Model: S-K16-AH
• Series: S-K16 Marine Heavy Industrial Level Switch Series
• Designation: AH (Top-Mounting, High-Level Detection / Standard Rod & Float Assembly)
• Manufacturer Part Number (MPN): S-K16-AH
• Enclosure / Terminal Head: Cast aluminum alloy / marine bronze option, IP66 / IP68 (submersible head variant), finished in corrosion-resistant marine epoxy.

Technical Details

Features

1. Hermetically Isolated Magnetic Coupling: Operates via repulsive/attractive permanent magnetic flux transferring movement across a solid non-magnetic stainless-steel diaphragm/chamber wall, eliminating mechanical gland packing, dynamic O-rings, and process fluid leaks into the switch chamber.
2. High Electrical Load Capability: Equipped with an industrial-grade SPDT snap-action microswitch carrying ratings of 15A at up to 480VAC and 0.5A at 30VDC, mitigating the need for interposing relays in standard contactor and annunciator control loops.
3. Marine-Hardened Mechanical Construction: Constructed with SUS304/SUS316 wetted parts, welded cylindrical stainless float, and high-tensile guide assembly engineered to resist severe cavitation, mechanical sloshing, and vessel rolling/pitching.
4. Top-Mounted Flange Configuration: Standardized JIS / ANSI flange pattern enables straightforward installation into deck plates, top manhole covers, and upper standpipes without tank emptying requirements.
5. Built-in Manual Test Mechanism (Inspection Device): Permits external physical verification of switch operation and alarm trip functionality during routine PSC (Port State Control), class surveys, or pre-departure checks without removing the unit from the tank.

Terminal Allocations & Wiring Schematic

• Terminal 1 (COM): Common contact for microswitch input signal.
• Terminal 2 (NO): Normally Open contact (Closes on rising liquid level / High Alarm activation).
• Terminal 3 (NC): Normally Closed contact (Opens on rising liquid level / Fail-safe trip activation).
• Terminal G / Earth: Internal enclosure chassis ground terminal for cable screen/braid and hull grounding.

Wiring Mode Logic:

• High Level Alarm (Normally De-energized loop): Connect to COM and NO. Contacts remain open at low/normal level and bridge across COM–NO upon float ascent.
• Fail-Safe High Level Alarm (Loop-Monitored / Normally Energized): Connect to COM and NC. If a cable fault, severed line, or high level occurs, the loop breaks, alerting the monitoring system.

System Compatibility

• Engine Room Alarm Systems (AMS): Kongsberg K-Chief / AutoChief, NABTESCO, Lyngsø Marine / SAM Electronics MCS, Consilium, Yanmar Engine Monitoring, Daihatsu Alarm Monitoring Systems.
• Pumping & Bunkering Automation: Bilge auto-start control circuits, high-level oily water separator (OWS) shutdown systems, overflow fuel transfer tank dump valves.
• Associated Machinery & Skids: Alfa Laval / Westfalia Fuel Oil Purifier sludge tanks, oily bilge settling tanks, sewage treatment plants (STP), ballast water management skids (BWMS).

Part Number Cross-References

• Sankyo Seisakusho Alternatives:
  • S-K16-AL: Top-mount configuration oriented specifically for low-level detection / pump dry-run trip.
  • S-K16-ES / S-K16ES-N: Horizontal side-mounted marine float level switch equivalent.
  • S-K16-BH / S-K16-BL: Chamber-type side-mounted float level switch.
  • S-K16AHS-85: Variant with specific insertion stem lengths and switch bracket offsets.
• Direct Marine Equivalents:
  • Musasino: LK-Series Top-Mounted Float Level Switches
  • Nakakita Seisakusho: NS / LS Series Magnetic Level Switches
  • Klay Instruments / Emerson / Mobrey: Vertical Magnetic Level Switches (e.g., Mobrey S01DB / S03DB equivalents for vertical orientation)

Marine Applications

• Heavy Fuel Oil (HFO) & Marine Diesel Oil (MDO) Tanks: Settling, service, and storage tank high-level and overflow alarms.
• Main Engine & Auxiliary Engine Systems: Sump tank low level, cylinder oil daily tanks, camshaft oil tanks, turbocharger drain collectors.
• Engine Room Bilge Wells & Bilge Holding Tanks: Oily water bilge high alarm triggering bilge pumps or dynamic separator trips.
• Freshwater & Sea Water Ballast Systems: Ballast tank point-level confirmation, forepeak/afterpeak tank high-level indication.
• Purifier / Separator Waste Systems: Sludge tank high-level interlocks and waste oil drain tanks.

Frequently Asked Questions

What is the primary difference between the Sankyo S-K16-AH and the S-K16-AL models?

The S-K16-AH model is calibrated and configured for High-Level Alarm and high-level control functions (the switch actuates as the float rises to the designated upper threshold). The S-K16-AL is calibrated for Low-Level Alarm duties (tripping when the liquid falls below a critical boundary, commonly utilized for dry-run protection on engine room pumps).

How does the magnetic coupling mechanism work?

The switch utilizes isolated magnetic coupling. Inside the wetted stem/guide, a magnet linked to the float moves adjacent to an opposing magnet inside the isolated, sealed terminal housing. The magnetic flux passes through a solid, non-magnetic stainless-steel boundary plate. Because there is no mechanical link or stuffing box penetrating into the switch box, oil and pressurized vapor cannot seep into the contact housing.

Can the S-K16-AH be connected directly to a 24V DC PLC input?

Yes. Although the switch has a heavy-duty contact rating (15A AC, 0.5A 30V DC), the silver-alloy microswitch contacts are completely compatible with dry-contact binary digital inputs (such as 24V DC marine automation PLC modules and distributed I/O racks).

Can the alarm activation level be adjusted in the field?

The actuation point is dictated by the float travel path along the vertical stem, which is restricted by upper and lower mechanical stoppers. On standard units, slight position adjustments can be made by resetting the locked stainless-steel collar stops, provided clearance allows sufficient magnetic linkage engagement.

Is this switch explosion-proof for hazardous areas?

Standard models feature high ingress protection (IP66/IP68) suitable for engine rooms, machinery spaces, and weather decks. When deployed in Zone 0 or Zone 1 hazardous areas (such as cargo pump rooms or flammable solvent lockers), the S-K16-AH must be wired through an intrinsically safe (IS) galvanic isolation barrier compliant with ATEX / IECEx requirements.